tag:theconversation.com,2011:/global/topics/fossil-record-43282/articlesFossil record – The Conversation2024-01-15T19:04:45Ztag:theconversation.com,2011:article/2181282024-01-15T19:04:45Z2024-01-15T19:04:45Z565-million-years-old, some of the oldest UK fossils are eerily similar to famous Australian ones<figure><img src="https://images.theconversation.com/files/562350/original/file-20231129-28-ulz8qc.jpg?ixlib=rb-1.1.0&rect=2%2C4%2C1531%2C1016&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ediacaran life as imagined by scientists in the 1980s.</span> <span class="attribution"><a class="source" href="https://en.m.wikipedia.org/wiki/File:Life_in_the_Ediacaran_sea.jpg">Ryan Somma/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Some half a billion years ago, life on Earth went through a huge transformation. In what is called <a href="https://www.annualreviews.org/doi/10.1146/annurev.earth.33.092203.122519">the Ediacaran period</a>, after billions of years of single-celled organisms, large multicellular organisms emerged in the fossil record.</p>
<p>These traces of the oldest complex ecosystems have been found in only a handful of locations around the world. The fossils were made by soft-bodied creatures covered by sand, creating impressions of their squashed remains imprinted into rock.</p>
<p>Evidence of these creatures was first found in the <a href="https://ediacarafoundation.org/visit/">Ediacara Hills</a>, in South Australia’s Flinders Ranges. The discovery was pivotal in defining the <a href="https://www.idunn.no/doi/10.1080/00241160500409223">Ediacaran period</a>: a time in Earth’s past characterised by a specific layer of rock which symbolises a significant change in history.</p>
<p>What was happening elsewhere at this time? <a href="https://www.nature.com/articles/268624a0">Similar-looking fossils</a> have been found in a disused quarry in a farmer’s field at Llangynog in Wales, but until now their precise age was unknown. </p>
<p>In a <a href="https://dx.doi.org/10.1144/jgs2023-081">new study published in Journal of the Geological Society</a>, we have dated these Welsh remnants of ancient marine life. Now, we can confirm they were near contemporaries of the famous South Australian fossils. </p>
<h2>A bookmark for rocks</h2>
<p>How do geologists figure out the age of fossils? Understanding the age of fossils is extremely useful for correlation and understanding how biological communities evolved.</p>
<p>Luckily, at least for us today, an environmental catastrophe loomed in the shallow sea where these Welsh organisms lived. </p>
<p><a href="https://theconversation.com/volcano-eruptions-are-notoriously-hard-to-forecast-a-new-method-using-lasers-could-be-the-key-207031">Volcanic explosions</a> threw mineral particles over the surrounding landscape and polluted the atmosphere with toxic gases.</p>
<p>The billowing red hot clouds created ash layers. These ash layers contain mineral grains that are <a href="https://www.britannica.com/science/isotope">isotopically</a> datable, acting like miniature stopwatches that record the time elapsed since they crystallised in a volcano. Hence, volcanic ash acts much like a bookmark in a sequence of rocks, tracking the moment of eruption.</p>
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<a href="https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a conic volcano in the distance spewing out an ash cloud" src="https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568992/original/file-20240112-19-9fua7r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Volcanic eruptions produce layers of ash that can be used as ‘bookmarks’ in the geological record.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/volcano-errupting-volcanic-erruption-3d-illustration-2213727917">CGS Graphics</a></span>
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<h2>A clock for rocks</h2>
<p>A clock tick-tocks every second, but how do we measure time when each tick takes a million years? We use a <a href="https://www.gsoc.org/news/2020/12/07/zircon">mineral called zircon</a>. </p>
<p>Trapped within zircon is some uranium that undergoes nuclear decay to lead over millions of years. Scientists know the rate at which this change occurs, so by analysing the composition of the crystal we can use the zircon as a geological clock.</p>
<p>The more precisely we measure the amount of uranium and lead, the more precise the clock. By carefully <a href="https://www.boisestate.edu/earth-isotope/labshare/id-tims-instructional-videos/">dissolving, heating and analysing zircon</a>, we have dated the rocks in Wales to 565 million years (plus or minus 0.1%). That is a precise death certificate for the fossils.</p>
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Read more:
<a href="https://theconversation.com/scientists-cant-agree-on-when-the-first-animals-evolved-our-research-hopes-to-end-the-debate-212076">Scientists can't agree on when the first animals evolved – our research hopes to end the debate</a>
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<h2>It’s life, but not as we know it</h2>
<p>Evidence from Ediacaran fossils implies that after four billion years of oceans containing single-celled microbes, suddenly – in geological terms at least – the seas teemed with new complex life. <a href="https://eos.org/features/hunting-rare-fossils-of-the-ediacaran">Ediacaran life is odd</a>, with strange soft-bodied forms whose interaction with the environment is unclear. </p>
<p>Were the creatures stationary, or did they move around and eat each other? In some ways these creatures would be strangely familiar, yet in another way, bizarre. </p>
<p>Some appeared fern-like, others like cabbages, and yet others were similar to modern <a href="https://www.britannica.com/animal/sea-pen">sea pens</a>, resembling fat, old-fashioned writing quills.</p>
<p>Nevertheless, fossils from this time preserve the earliest evidence for large-scale multicellular organisms, <a href="https://www.australianenvironmentaleducation.com.au/education-resources/life-in-the-ediacaran/">including the first animals</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Green hills stretching to the horizon with clouds above and a few sheep in the foreground" src="https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568974/original/file-20240111-17-he84nu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The rolling countryside of mid-south Wales – hidden away in these hills is evidence of ancient life.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rolling-agricultural-hills-mid-wales-landscape-2095266949">Parkerspics</a></span>
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<h2>A tropical paradise?</h2>
<p>Half a billion years ago, Wales was not green and sheep covered and looked much more like a barren volcanic island. The Llangynog fossils are fascinating because they record a shallow marine ecosystem. </p>
<p>In contrast, other famous fossil sites like <a href="https://www.bgs.ac.uk/news/560-million-year-old-fossil-is-first-animal-predator/">Charnwood Forest in the United Kingdom</a> and <a href="https://whc.unesco.org/en/list/1497/">Mistaken Point, Canada</a> record deep-marine conditions.</p>
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<a href="https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular impression on a grey rock with a 20mm scale in the corner" src="https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=503&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=503&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=503&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=632&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=632&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565985/original/file-20231215-15-xkahqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=632&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption"><em>Aspidella</em>, one of the weird and wonderful fossils of Llangynog, Wales.</span>
<span class="attribution"><span class="source">Anthony Clarke</span></span>
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<p>In the shallow waters of the chain of tropical volcanic islands that’s now Wales, a creature called <em>Aspidella terranovica</em> felt the warmth of sunlight and the sway of the tides 565 million years ago. This fossil is rare and valuable because it shows evidence of movement.</p>
<p>Alongside <em>Aspidella</em>, other disc-like organisms are preserved; these could represent the anchor for fern-shaped filter feeders.</p>
<p>Hidden away in an unassuming quarry in Wales are the remnants of a diverse shallow marine ecosystem containing some of Britain’s oldest fossils, which we have proved have cousins of a similar age in Australia. This time in Earth’s history was just after a <a href="https://theconversation.com/how-snowball-earth-volcanoes-altered-oceans-to-help-kickstart-animal-life-53280">global glaciation</a> so severe and widespread that some researchers consider the entire planet froze into a “snowball”. </p>
<p>The Ediacaran fossils show this thaw-out heralded evolutionary change, demonstrating a profound link between our planet’s geological processes and its biological cargo.</p>
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Read more:
<a href="https://theconversation.com/friday-essay-the-silence-of-ediacara-the-shadow-of-uranium-72058">Friday essay: the silence of Ediacara, the shadow of uranium</a>
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<img src="https://counter.theconversation.com/content/218128/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Kirkland receives funding from the Australian Research Council and various state government organisations within Australia.</span></em></p><p class="fine-print"><em><span>Anthony Clarke receives funding from the Australian Research Council.</span></em></p>Fossil traces of the oldest complex ecosystems are found in precious few locations worldwide, including Australia. Newly dated fossils from Wales now join the ranks.Chris Kirkland, Professor of Geochronology, Curtin UniversityAnthony Clarke, PhD Student in Applied Geology, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2132942023-10-05T15:49:43Z2023-10-05T15:49:43ZFossil snake traces: another world-first find on South Africa’s Cape south coast<figure><img src="https://images.theconversation.com/files/550184/original/file-20230926-29-aodxzb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Puff adders leave linear, sometimes slightly undulating traces.</span> <span class="attribution"><span class="source">EcoPrint/Shutterstock</span></span></figcaption></figure><p>Snakes are familiar, distinctive – and often feared – reptiles. And they’ve been around for a long time: body fossils found in the UK, Portugal and the US stretch all the way back to <a href="https://doi.org/10.1038/ncomms6996">the late Jurassic period</a>, about 150 million years ago.</p>
<p>Until now, though, there hasn’t been a single description of a surface fossilised snake trace – a mark on a surface that’s become cemented and re-exposed over time – anywhere in the world. </p>
<p>There are probably several reasons for this. One is that the tracks of large quadrupeds (four-legged animals), including dinosaurs, are easier to recognise than those of snakes. Another reason could be that snakes tend to avoid sandy or muddy areas in which their trails could be registered, preferring vegetated terrain. Maybe, as the weight of the snake is distributed over its entire length, the trails are shallow and are not easy to identify. </p>
<p>Or perhaps researchers are not adequately familiar with the types of traces that snakes can create. </p>
<p>We are part of an <a href="https://theconversation.com/my-job-is-full-of-fossilised-poop-but-theres-nothing-icky-about-ichnology-182906">ichnological team</a> – experts in identifying fossil tracks and traces. In a <a href="https://www.tandfonline.com/doi/abs/10.1080/10420940.2023.2250062?src=">recently published article</a> in the journal <em>Ichnos</em>, we described the first snake trace in the fossil record, which we found on South Africa’s Cape south coast. It dates to the <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene epoch</a>, and our studies have shown that it was probably made between 93,000 and 83,000 years ago, almost certainly by a puff adder (<em>Bitis arietans</em>).</p>
<p>As this is a world first, our research team was obliged to create a new ichnogenus and ichnospecies, <em>Anguinichnus linearis</em>, to describe the distinctive pattern in the sand registered by the puff adder. </p>
<h2>A snake and a buffalo</h2>
<p>The puff adder is a not uncommon sight on the Cape south coast today and, with good reason, strikes fear into residents and visitors: its cytotoxic (tissue-destroying) venom can cause the loss of a limb or worse. It habitually suns itself on trails, staying motionless, and then strikes without warning.</p>
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Read more:
<a href="https://theconversation.com/the-ultimate-in-stealth-puff-adders-employ-camouflage-at-every-level-53316">The ultimate in stealth, puff adders employ camouflage at every level</a>
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<p>We found the trace fossil in the <a href="https://www.capenature.co.za/reserves/walker-bay-nature-reserve">Walker Bay Nature Reserve</a> (adjacent to <a href="https://www.grootbos.com/en">Grootbos Private Nature Reserve</a>), just over 100 kilometres south-east of Cape Town. </p>
<p>Intriguingly, a <a href="https://prehistoric-fauna.com/Pelorovis-antiquus">long-horned buffalo</a> – an extinct species – had walked across the same dune surface soon after the snake left its trace. We know this because one of the buffalo’s tracks is superimposed on the puff adder trace, slightly deforming it.</p>
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<img alt="A large, smooth, light grey rock surface on which the indent of a slithering snake is visible, as are several hoof prints" src="https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551116/original/file-20230929-21-r9kbpi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The puff adder trail, crossed by a long-horned buffalo trackway. Geological hammer for scale.</span>
<span class="attribution"><span class="source">Hayley Cawthra</span></span>
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<p>The puff adder and long-horned buffalo traces were found on the surface of a loose slab, 3 metres long and 2.6 metres wide, which had become dislodged and fallen down onto the beach from overlying cliffs. The slab is submerged twice a day by high tides. We were fortunate to discover it when its surface was bare, as repeat visits have shown that it is often covered in algae or by a thick layer of beach sand.</p>
<h2>Snakes in motion</h2>
<p>Snakes use four main types of locomotion. Each results in distinctive, recognisable traces. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/7-AKPFiIEEw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Here’s how snakes move through the world.</span></figcaption>
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<p>Puff adders are heavy, thick-set snakes with an average adult length of less than a metre. They mostly employ rectilinear motion, leaving a linear, sometimes slightly undulating trace, often with a central drag mark registered by the tail tip. In this form of motion the snake uses its weight and its belly muscles and grips rough areas on the surface with the posterior edges of its scales. It is drawn forwards through the muscular contractions, creating a linear trace. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/iWZfIzIayDk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A puff adder in motion, filmed by research team member Mark Dixon.</span></figcaption>
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<p>We also found possible trace evidence at other sites on the Cape south coast of sidewinding and undulatory motion, but this was inconclusive. We will be looking for further, more conclusive evidence. </p>
<h2>Filling important gaps</h2>
<p>The newly described puff adder traces help fill a gap in the Pleistocene trace fossil record from the region. <a href="https://doi.org/10.1016/j.quascirev.2019.07.039">More than 350 vertebrate tracksites</a> have been identified, of mammals, birds and reptiles. Most of these sites were registered on dune surfaces, which have now become <a href="https://doi.org/10.1016/S0012-8252(01)00054-X">cemented into aeolianites and re-exposed</a>. Our latest find is yet another global first for the Cape south coast. </p>
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Read more:
<a href="https://theconversation.com/first-fossil-trails-of-baby-sea-turtles-found-in-south-africa-122434">First fossil trails of baby sea turtles found in South Africa</a>
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<p>With other vertebrate groups, such as dinosaurs and crocodiles, the trace fossil record has substantially augmented the body fossil record, providing new insights. Hopefully this discovery will act as a spur to identify other snake traces from around the world from older deposits, and thus increase our understanding of the evolution of snakes and help to fill a substantial gap in the global trace fossil record.</p><img src="https://counter.theconversation.com/content/213294/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The trace was probably made between 93,000 and 83,000 years ago, almost certainly by a puff adder.Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityHayley Cawthra, Specialist Scientist, Council for GeoscienceLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2117122023-08-17T19:42:11Z2023-08-17T19:42:11ZA changing climate, growing human populations and widespread fires contributed to the last major extinction event − can we prevent another?<p>Over the past decade, deadly wildfires have become increasingly common because of both <a href="https://www.scientificamerican.com/article/climate-change-is-escalating-californias-wildfires/">human-caused climate change</a> and <a href="https://www.nytimes.com/2023/08/13/us/hawaii-wildfire-factors.html">disruptive land management practices</a>. Southern California, where the three of us live and work, has been <a href="https://ktla.com/news/the-cities-where-wildfires-threaten-the-most-homes-in-california/">hit especially hard</a>.</p>
<p>Southern California also experienced a wave of wildfires 13,000 years ago. These fires permanently transformed the region’s vegetation and <a href="https://www.science.org/doi/10.1126/science.abo3594">contributed to Earth’s largest extinction</a> in more than 60 million years.</p>
<p>As <a href="https://www.ioes.ucla.edu/person/emily-lindsey/">paleontologists</a>, <a href="https://nhm.org/person/dunn-regan">we have</a> a <a href="https://scholar.google.com/citations?user=_FveDz4AAAAJ&hl=en">unique perspective</a> on the long-term causes and consequences of environmental changes, both those linked to natural climate fluctuations and those wrought by humans. </p>
<p><a href="https://www.science.org/doi/10.1126/science.abo3594">In a new study</a>, published in August 2023, we sought to understand changes that were happening in California during the last major extinction event at the <a href="https://www.britannica.com/science/Pleistocene-Epoch">end of the Pleistocene</a>, a time period known as the Ice Age. This event wiped out <a href="https://www.smithsonianmag.com/science-nature/what-happened-worlds-most-enormous-animals-180964255/">most of Earth’s large mammals</a> between about 10,000 and 50,000 years ago. This was a time marked by dramatic climate upheavals and rapidly spreading human populations. </p>
<h2>The last major extinction</h2>
<p>Scientists often call the past 66 million years of Earth’s history the Age of Mammals. During this time, our furry relatives took advantage of the <a href="https://www.nhm.ac.uk/discover/how-an-asteroid-caused-extinction-of-dinosaurs.html">extinction of the dinosaurs</a> to become the dominant animals on the planet. </p>
<p>During the Pleistocene, Eurasia and the Americas teemed with enormous beasts like woolly mammoths, giant bears and dire wolves. Two species of camels, three species of ground sloths and five species of large cats <a href="https://tarpits.org/research-collections/tar-pits-collections/mammal-collections">roamed what is now Los Angeles</a>.</p>
<p>Then, abruptly, they were gone. All over the world, the large mammals that had characterized global ecosystems for tens of millions of years disappeared. North America <a href="https://www.doi.org/10.1146/annurev.ecolsys.34.011802.132415">lost more than 70%</a> of mammals weighing more than 97 pounds (44 kilograms). South America lost more than 80%, Australia nearly 90%. Only Africa, Antarctica and a few remote islands retain what could be considered “natural” animal communities today.</p>
<p>The reason for these extinctions remains obscure. For decades, paleontologists and archaeologists have debated potential causes. What has befuddled scientists is not that there are no obvious culprits but that there are too many. </p>
<p>As the last ice age ended, a warming climate led to altered weather patterns and the reorganization of <a href="https://doi.org/10.1016/j.quascirev.2015.08.029">plant communities</a>. At the same time, human populations were rapidly increasing and <a href="https://www.worldhistory.org/article/1070/early-human-migration/">spreading around the globe</a>. </p>
<p>Either or both of these processes could be implicated in the extinction event. But the fossil record of any region is usually too sparse to know exactly when large mammal species disappeared from different regions. This makes it difficult to determine whether habitat loss, resource scarcity, natural disasters, human hunting or some combination of these factors is to blame.</p>
<h2>A deadly combination</h2>
<p>Some records offer clues. <a href="https://tarpits.org/">La Brea Tar Pits</a> in Los Angeles, the world’s richest ice age fossil site, preserves the bones of thousands of large mammals that were trapped in viscous asphalt seeps <a href="https://resolver.caltech.edu/CaltechAUTHORS:20191203-160736818">over the past 60,000 years</a>. Proteins in these bones can be precisely dated <a href="https://doi.org/10.1016/j.quageo.2014.03.002">using radioactive carbon</a>, giving scientists unprecedented insight into an ancient ecosystem and an opportunity to illuminate the timing – and causes – of its collapse. </p>
<p>Our recent study from La Brea Tar Pits and <a href="https://en.wikipedia.org/wiki/Lake_Elsinore">nearby Lake Elsinore</a> has unearthed evidence of a dramatic event 13,000 years ago that permanently transformed Southern California’s vegetation and <a href="https://www.science.org/doi/10.1126/science.abo3594">caused the disappearance</a> of La Brea’s iconic mega-mammals. </p>
<p>Sediment archives from the lake’s bottom and archaeological records provide evidence of a deadly combination – a warming climate <a href="https://doi.org/10.1002/jqs.3018">punctuated by decadeslong droughts</a> and rapidly rising human populations. These factors pushed the Southern California ecosystem to a tipping point. </p>
<p><a href="https://www.doi.org/10.1126/sciadv.1501682">Similar combinations</a> of climate warming and human impacts have been blamed for ice age extinctions elsewhere, but our study found something new. The catalyst for this dramatic transformation seems to have been an unprecedented increase in wildfires, which were probably set by humans. </p>
<p>The processes that led to this collapse are familiar today. As California warmed coming out of the last ice age, the landscape became drier and forests receded. At La Brea, herbivore populations declined, probably from a combination of human hunting and habitat loss. Species associated with trees, like camels, disappeared entirely. </p>
<p>In the millennium leading up to the extinction, mean annual temperatures in the region <a href="https://doi.org/10.1016/j.epsl.2019.03.024">rose 10 degrees Farenheit</a> (5.5 degrees Celsius), and the lake began evaporating. Then, 13,200 years ago, the ecosystem entered a 200-year-long drought. Half of the remaining trees died. With fewer large herbivores to eat it, dead vegetation built up on the landscape. </p>
<p>At the same time, human populations began expanding across North America. And as they spread, people brought with them a powerful new tool – fire. </p>
<p>Humans and our ancestors have used fire for <a href="https://www.science.org/content/article/artificial-intelligence-may-have-unearthed-one-world-s-oldest-campfires">hundreds of thousands of years</a>, but fire has <a href="https://www.firescience.gov/projects/09-2-01-9/supdocs/09-2-01-9_Chapter_3_Fire_Regimes.pdf">different impacts in different ecosystems</a>. Charcoal records from Lake Elsinore reveal that before humans, fire activity was low in coastal Southern California. But 13,200 to 13,000 years ago, as human populations grew, fire in the region increased by an order of magnitude. </p>
<p>Our research suggests that the combination of heat, drought, herbivore loss and human-set fires had pushed this system to a <a href="https://www.nature.com/articles/nature11018">tipping point</a>. At the end of this period, Southern California was covered in chaparral plants, which thrive after fires. A new fire regime had become established, and the iconic La Brea megafauna had disappeared.</p>
<h2>Lessons for the future</h2>
<p>Studying the causes and consequences of the Pleistocene extinctions in California can provide valuable context for understanding today’s climate and biodiversity crises. A similar combination of climate warming, expanding human populations, biodiversity loss and human-ignited fires that characterized the ice age extinction interval in Southern California are <a href="https://www.doi.org/10.1126/science.abb0355">playing out again today</a>.</p>
<p>The alarming difference is that temperatures today are rising <a href="https://www.scientificamerican.com/article/todays-climate-change-proves-much-faster-than-changes-in-past-65-million-years/">10 times faster</a> than they did at the end of the ice age, primarily because of the burning of fossil fuels. This human-caused climate change has contributed to a fivefold increase in fire frequency and intensity and the amount of area burned in the state of California in the <a href="https://doi.org/10.1029/2019EF001210">past 45 years</a>. </p>
<p>While California is now <a href="https://earthobservatory.nasa.gov/images/148908/whats-behind-californias-surge-of-large-fires">famous for extreme fires</a>, our study reveals that fire is a relatively new phenomenon in this region. In the 20,000 years leading up to the extinction, the Lake Elsinore record shows very low incidence of any fire even during comparable periods of drought. Only after human arrival does fire become a regular part of the ecosystem. </p>
<p>Even today, <a href="https://www.businessinsider.com/pge-caused-california-wildfires-safety-measures-2019-10">downed power lines</a>, campfires and <a href="https://www.nytimes.com/2020/09/07/us/gender-reveal-party-wildfire.html">other human activities</a> start <a href="https://doi.org/10.1071/WF18026">over 90%</a> of wildfires in coastal California. </p>
<p>The parallels between the late Pleistocene megafaunal extinctions and today’s environmental crises are striking. The past teaches us that the ecosystems we depend upon are vulnerable to collapse when stressed by multiple intersecting pressures. Redoubling efforts to eliminate greenhouse gas emissions, prevent reckless fire ignitions and preserve Earth’s remaining megafauna can help avert another, even more catastrophic transformation.</p><img src="https://counter.theconversation.com/content/211712/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Lindsey receives funding from the National Science Foundation, which funded some of the research reported in this article. </span></em></p><p class="fine-print"><em><span>Lisa N. Martinez receives funding from the National Science Foundation and the UCLA Endowed Chair in Geography of California and the American West. </span></em></p><p class="fine-print"><em><span>Regan E. Dunn receives funding from National Science Foundation and NASA. </span></em></p>New findings from the La Brea Tar Pits in southern California suggest human-caused wildfires in the region, along with a warming climate, led to the loss of most of the area’s large mammals.Emily Lindsey, Associate Curator, La Brea Tar Pits; Adjunct Faculty, Institute of the Environment and Sustainability, UCLA, University of California, Los AngelesLisa N. Martinez, Ph.D. Candidate in Geography, University of California, Los AngelesRegan E. Dunn, Adjunct Professor of Earth Sciences, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2065012023-05-30T14:02:40Z2023-05-30T14:02:40ZThese magnificent 107-million-year-old pterosaur bones are the oldest ever found in Australia<p>New research on old bones has shed light on pterosaur fossils from the early Cretaceous period of Australia, which took place roughly 107 million years ago.</p>
<p>The bones were discovered in Victoria in the late 1980s at a fossil site called <a href="https://museumsvictoria.com.au/article/the-700/">Dinosaur Cove</a>, a few hours’ drive west of Melbourne.</p>
<p>Our paper describing the bones is <a href="https://tandfonline.com/doi/full/10.1080/08912963.2023.2201827">published today in Historical Biology</a>.</p>
<h2>The oldest pterosaur bones we have</h2>
<p>The Dinosaur Cove fossils are the geologically oldest pterosaur remains we have from the <a href="https://www.britannica.com/science/Cretaceous-Period/Major-subdivisions-of-the-Cretaceous-System">Lower Cretaceous</a> of Australia. </p>
<p>These bones belonged to two separate individuals, because there’s a relative size difference between the two.</p>
<p>One specimen is a partial sacrum (the fused vertebrae from between the pelvic bones), a relative rarity in the pterosaur fossil record. The other is a comparatively small fourth metacarpal (part of the wing finger) – it is the first evidence of a juvenile pterosaur found in Australia.</p>
<p>Although we couldn’t pinpoint exactly which species in the pterosaur family these bones came from, the partial sacrum belonged to an individual with a wingspan estimated to exceed two metres. By contrast, the juvenile pterosaur had a wingspan just over one metre. </p>
<figure class="align-center ">
<img alt="Silhouettes of a woman compared with Australian Cretaceous pterosaurs" src="https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=376&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=376&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528526/original/file-20230526-21-5fzgqw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=376&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wingspan estimates of Australian pterosaurs, including <em>Ferrodraco lentoni</em>, an adult from the Upper Cretaceous of Queensland, compared with the newly described Victorian pterosaurs from the Lower Cretaceous.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>In the early Cretaceous, approximately 110–107 million years ago, Victoria was virtually unrecognisable. The Bass Strait was a narrow valley occupied by fast-flowing rivers. Conifers and ginkgoes grew here instead of eucalypts and grasses, and dinosaurs reigned.</p>
<p>On the ground, the dominant herbivore animals were <a href="https://theconversation.com/meet-the-diverse-group-of-plant-eating-dinosaurs-that-roamed-victoria-110-million-years-ago-166343">small-bodied, beaked ornithopods</a>, perpetually wary of the <a href="https://www.swinburne.edu.au/news/2019/10/huge-clawed-predatory-dinosaur-discovery-in-victoria/">rapacious megaraptoran theropods</a>.</p>
<p>For more than 30 years, it has been clear to scientists that flying reptiles called pterosaurs soared through the Victorian Cretaceous skies, above the heads of the dinosaurs. Until recently, however, they have remained a mystery.</p>
<h2>Treasure at Dinosaur Cove</h2>
<p>Large-scale excavations at <a href="https://depositsmag.com/2020/07/02/hell-and-high-water-the-digs-of-dinosaur-cove/">Dinosaur Cove</a> began in 1984, and for more than 40 years, a team of volunteers called <a href="http://dinosaurdreaming.monash.edu/">Dinosaur Dreaming</a> have excavated fossil sites along several other sites scattered across the Victorian coast.</p>
<p><a href="https://museumsvictoria.com.au/about-us/staff/dr-thomas-rich/">Tom Rich</a> and <a href="https://research.monash.edu/en/persons/patricia-rich">Pat Vickers-Rich</a>, co-authors of our newly published paper, led the excavations that yielded not just the newly described pterosaurs, but myriad other discoveries as well. </p>
<figure class="align-center ">
<img alt="Two palaeontologists holding pterosaur bones" src="https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528532/original/file-20230526-27-8vpr49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Co-authors Pat Vickers-Rich and Tom Rich holding the pterosaur specimens we described.</span>
<span class="attribution"><span class="source">Tim Ziegler, Author provided</span></span>
</figcaption>
</figure>
<p>The work at this rich fossil site has resulted in thousands of dinosaur bones and other fossils. These include fossil fish (bony fish and lungfish), skeletal remains from ornithopods, megaraptoran theropods, aquatic plesiosaurs and prehistoric mammals. There was also <a href="https://ecoevocommunity.nature.com/posts/a-tiny-dinosaur-bone-with-a-big-story-to-tell-australia-s-first-elaphrosaur">Australia’s only elaphrosaurine theropod</a>: a lightly-built dinosaur with a small head, long neck, relatively short front limbs, long hind limbs and a long tail.</p>
<p>But among the rarest vertebrate fossils from Dinosaur Cove are those from pterosaurs.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-diverse-group-of-plant-eating-dinosaurs-that-roamed-victoria-110-million-years-ago-166343">Meet the diverse group of plant-eating dinosaurs that roamed Victoria 110 million years ago</a>
</strong>
</em>
</p>
<hr>
<h2>Australia’s pterosaur record</h2>
<p>The majority of Australia’s pterosaur fossils have been found in central-western Queensland. Indeed, <a href="https://www.nature.com/articles/288361a0">the first pterosaurs reported from the continent</a> were isolated remains from the Eromanga Basin, described in 1980.</p>
<p>Since then, more pterosaur material has come to light, with four Australian pterosaur species currently recognised: <a href="https://www.sciencedirect.com/science/article/pii/S0195667118302775"><em>Mythunga camara</em></a>, <a href="https://www.scielo.br/j/aabc/a/cbd3DSy74yzYnnrTvfqw73M/?format=pdf&lang=en"><em>Aussiedraco molnari</em></a>, <a href="https://www.nature.com/articles/s41598-019-49789-4"><em>Ferrodraco lentoni</em></a> and <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2021.1946068"><em>Thapunngaka shawi</em></a>.</p>
<p><em>Ferrodraco</em> is the most complete Australian pterosaur to date, and is represented by <a href="https://www.tandfonline.com/doi/full/10.1080/02724634.2021.2038182">an adult individual with a wingspan of approximately four metres</a>, which we named as a new species in 2019.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/4-metre-flying-reptile-unearthed-in-queensland-is-our-best-pterosaur-fossil-yet-124581">4-metre flying reptile unearthed in Queensland is our best pterosaur fossil yet</a>
</strong>
</em>
</p>
<hr>
<p>Other pterosaur fossils from Australia include isolated remains from the Cretaceous of Western Australia, and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5419211/">opalised pterosaur teeth</a> from the mid-Cretaceous of Lightning Ridge in New South Wales.</p>
<figure class="align-right ">
<img alt="Three pterosaur wing bones" src="https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528531/original/file-20230526-17-nzdm20.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Three pterosaur wing bones from three individuals. Left: right metacarpal from the Toolebuc Formation was discovered at Slashers Creek Station, east of Boulia, Queensland. Middle: Left metacarpal from <em>Ferrodraco lentoni</em> from the Winton Formation, discovered northeast of Winton, Queensland. Right: a left metacarpal from a juvenile pterosaur from Dinosaur Cove, Victoria.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>We don’t know which species the Victorian pterosaurs belong to. However, the comparatively small fourth metacarpal – a bone from the wing – is the first unequivocal evidence of a juvenile pterosaur from Australia. </p>
<h2>Pterosaurs at high latitudes</h2>
<p>Few pterosaur remains have been reported from fossil sites that were at high latitudes during the Age of Reptiles – the Mesozoic Era.</p>
<p>Antarctica, which was at high latitudes throughout, <a href="https://www.scielo.br/j/aabc/a/CcYBLYkgDhfJfvQDNdRxK4m/?lang=en">has produced three pterosaur fossils</a>. One of these awaits formal description, and another was <a href="https://theconversation.com/lesson-from-brazil-museums-are-not-forever-102692">recovered from the charred remains of the National Museum of Brazil</a>.</p>
<p>The only reports of high-latitude pterosaurs in the northern hemisphere are of <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/let.12006?casa_token=zOdjm4--NfkAAAAA%3A8_IIW_UhaReQVG1aohnc24Sl5BFtEqdWlYm4jEN_b-OTM5Ghdd_umZyigE1Y8gaxkMwwKnie0eSML8pt">isolated footprints</a>.</p>
<p>During the Cretaceous, <a href="https://www.geologypage.com/wp-content/uploads/2014/04/CretaceousPeriod.jpg">Australia was farther south than it is today</a>. In fact, Victoria was within the polar circle during much of the Cretaceous. Southeast Australia was not frozen over at this time, but there were weeks or months of continuous darkness during the winter. Despite these <a href="https://www.amazon.com/Dinosaurs-Darkness-Second-Search-Polar/dp/0253029406">harsh polar conditions</a>, life found a way to survive and thrive. </p>
<p>This prompts a few questions: were pterosaurs permanent residents in southeast Australia? Or did they migrate south during summer and head north for the winter?</p>
<p><a href="https://www.nature.com/articles/s41598-021-92499-z">From a young age, pterosaurs were adept fliers</a>, their bones already able to withstand the stresses of both launch and flight. However, subtle variations in the shape of the bones imply that hatchlings differed from their adult counterparts in terms of speed and manoeuvrability. </p>
<p>Until we discover pterosaur eggs or embryonic individuals at sites that were at high latitudes at the time, we won’t be able to confirm if pterosaurs were year-round residents or migratory.</p>
<p>Despite the rarity of pterosaurs in the fossil record, it is only a matter of time before we find more complete pterosaur material from Dinosaur Cove and other Cretaceous sites from coastal Victoria. Then, we can finally uncover the identity of these ancient, enigmatic winged reptiles.</p><img src="https://counter.theconversation.com/content/206501/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adele Pentland receives funding from the Australian Government Research Training Program Stipend.</span></em></p><p class="fine-print"><em><span>Stephen Poropat does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the dinosaur era, flying reptiles soared in the skies of what is now Australia – but we have barely any fossil records of them.Adele Pentland, PhD candidate, Curtin UniversityStephen Poropat, Research associate, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1907492022-09-28T20:02:11Z2022-09-28T20:02:11ZA kung-fu kick led researchers to the world’s oldest complete fish fossils – here’s what they found<figure><img src="https://images.theconversation.com/files/486470/original/file-20220926-14-8xjh44.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3425%2C1654&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Heming Zhang</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Some of the world’s most significant fossil discoveries have come from China. These include amazing <a href="https://www.nationalgeographic.com/animals/article/160405-dinosaurs-feathers-birds-museum-new-york-science">feathered dinosaurs</a>, the <a href="https://www.nbcnews.com/id/wbna44259687">earliest modern mammals</a>, and some of the <a href="https://whc.unesco.org/en/list/1388/">oldest-known animals on Earth</a>. </p>
<p>Today, <a href="https://www.nature.com/articles/s41586-022-05136-8">four</a> <a href="https://www.nature.com/articles/s41586-022-04897-6">new</a> <a href="https://www.nature.com/articles/s41586-022-05166-2">papers</a> <a href="https://www.nature.com/articles/s41586-022-05233-8">published</a> in Nature carry on this tradition by revealing the world’s oldest well-preserved jawed fishes, dating between 436 million and 439 million years ago to the start of the Silurian period. </p>
<p>The fossil discoveries all come from new fossil sites in the Guizhou and Chongqing Provinces in China. The Chongqing site was found in 2019, when three young Chinese palaeontologists were play fighting, and one was kung-fu kicked into the outcrop. Rocks tumbled down, revealing a spectacular fossil inside. </p>
<p>The research teams behind the papers are led by <a href="http://sourcedb.ivpp.cas.cn/yw/rckyw/200908/t20090811_2364087.html">Zhu Min</a> of the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing. Min told me:</p>
<blockquote>
<p>The discovery of the Chongqing <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/lagerstatte">lagerstatte</a> (a “lagerstatte” is a fossil site of exceptional preservation) is indeed an unbelievable miracle of fossil hunting. Suddenly we realised we have found a jaw-dropping lagerstatte. We are now close to the core of untangling the fishy tree of early jawed vertebrates.</p>
</blockquote>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/v218qXlus_4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>What kinds of fishes were they?</h2>
<p>Most fishes today fall into two main groups: </p>
<ul>
<li>the <a href="https://ucmp.berkeley.edu/vertebrates/basalfish/chondrintro.html">chondrichthyans</a> (which includes sharks, rays and chimaerids) have cartilaginous skeletons</li>
<li>and the <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/osteichthyes">osteichthyans</a> (bony fishes such as trout) have bone forming the skeleton.</li>
</ul>
<p>The origins of these living fish groups are now much clearer due to the new findings of the oldest complete fishes from China. </p>
<p>These were shark-like fishes. Some were <a href="https://ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html">placoderms</a>, an extinct class of armoured fish that had bony plates forming a solid shield around the head and trunk. </p>
<p>Others were ancestral kinds of sharks called acanthodians. These are extinct forms of “stem-sharks” that evolved as a separate branch – or stem – of the evolutionary line that led to modern sharks.</p>
<p>Placoderms are the earliest-known jawed vertebrates. Researching them is important as they help reveal the origins of many parts of the human body (including our <a href="https://theconversation.com/we-found-the-oldest-ever-vertebrate-fossil-heart-it-tells-a-380-million-year-old-story-of-how-our-bodies-evolved-190230">hearts</a> and <a href="https://theconversation.com/hello-fish-face-a-fossil-fish-reveals-the-origins-of-the-face-22976">faces</a>). </p>
<p>A small flattened placoderm called <em>Xiushanosteus</em>, about three centimetres long, is the most common fish found at the new Chongqing site.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=376&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=376&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485763/original/file-20220921-16-86cwmb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=376&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The very small <em>Xuishanosteus</em> is the oldest-known placoderm fish. It shows features typical of later forms from the Devonian period.</span>
<span class="attribution"><span class="source">Heming Zhang</span></span>
</figcaption>
</figure>
<p>Its skull shows paired bones which reflect those on top of our own heads. Frontal and parietal bones have their origin in these fishes. Zhu You-an, who led the study on these fishes, told me: </p>
<blockquote>
<p>All the things are still like dreams. Today we are staring at complete early Silurian fishes, 11 million years earlier than the previous oldest finds! These are both the most exciting, as well as the most challenging fossils I have had the privilege to work on!</p>
</blockquote>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486464/original/file-20220926-23-jjbzg8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Zhu Min and the team collected Silurian fossils on a rainy day in Chongqing.</span>
<span class="attribution"><span class="source">Zhu Min et al.</span></span>
</figcaption>
</figure>
<h2>The world’s oldest sharks and teeth</h2>
<p>The new papers also describe the oldest complete shark-like fish, named <em>Shenacanthus</em>. It has a body shape similar to other prehistoric <a href="https://www.the-scientist.com/the-nutshell/sharks-may-have-evolved-from-acanthodians-31858">acanthodians</a> (or stem-sharks) – but differs in having thick plates forming armour around it, as seen in placoderms. </p>
<p>The fact that <em>Shenacanthus</em> shares the features of both acanthodians and placoderms suggests these two groups evolved from similar ancestral stock. That said, <em>Shenacanthus</em> retains typical shark-like fin spines so it’s not regarded a placoderm, but a chondrichthyan (the group including today’s cartilaginous sharks).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=208&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=208&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=208&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=262&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=262&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486466/original/file-20220926-25-ingioe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=262&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Shenacanthus</em> is shown restored here. It’s the oldest chondrichthyan fish known by more than just scales.</span>
<span class="attribution"><span class="source">Heming Zhang</span></span>
</figcaption>
</figure>
<p>The research also reveals the oldest-known teeth of any vertebrate – at least 14 million years older than any previous findings. Coming from a fossil chondrichthyan named <em>Qianodus</em>, the teeth are arranged as coiled rows called “whorls”. Such tooth whorls are common at the junction of the jaws in many ancient sharks and some early bony fishes such as <em>Onychodus</em>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=280&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=280&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=280&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=352&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=352&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486455/original/file-20220926-11-3ixjga.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=352&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A reconstruction of Qianodus (left), an early fossil chondrichthyan that shows the oldest evidence of teeth in any vertebrate.</span>
<span class="attribution"><span class="source">Heming Zhang (artwork) / Plamen Andreev (CT image).</span></span>
</figcaption>
</figure>
<p>The researchers also found another early stem shark called <em>Fangjinshania</em> at the new site in Giuzhou. More than 300 kilograms of rock were collected and dissolved in weak acetic acid to free thousands of microscopic bits of bone and teeth. </p>
<p><em>Fangjinshania</em> resembles a stem shark called <em>Climatius</em> known to have lived about 30 million years later in Europe and North America. <em>Fangjinshania</em> lived as far back as 436 million years ago, which tells us the fossil record of such sharks is much older than we previously thought. </p>
<p>Both <em>Fangjinshania</em> and <em>Qianodus</em> were about 10cm-15cm long, making them many times larger than the placoderms and the <em>Shenacanthus</em>. They would have been the top predators in their ancient ecosystem, and the world’s first predators armed with sharp teeth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=208&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=208&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=208&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=262&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=262&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486467/original/file-20220926-19-3bo2d7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=262&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Fanjingshania</em> provides evidence all jawed vertebrates probably underwent a great evolutionary ‘radiation’ (major diversification) in the Ordovician period, more than 450 million years ago.</span>
<span class="attribution"><span class="source">Heming Zhang</span></span>
</figcaption>
</figure>
<p>Plamen Andreev, the lead author on two of the new papers, told me: </p>
<blockquote>
<p>These new finds give support to the idea that older fossil shark-like scales found in the Ordovician period could now really be called sharks.</p>
</blockquote>
<h2>From fins to limbs</h2>
<p>Another interesting discovery from these fossils concerns how paired limbs in vertebrates first evolved. A new jaw-less fish called <em>Tujiiaspis</em> now shows the primitive condition of paired fins before they separated into pectoral and pelvic fins – the forerunner to arms and legs.</p>
<p>Pectoral fins were thought to have evolved in jawless fishes called <a href="https://www.miguasha.ca/mig-en/osteostracans.php">osteostracans</a>, then pelvic fins later in placoderms. But the new <em>Tujiiaspis</em> fossil suggests both sets of fins could have evolved at the <a href="https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/dvdy.192">same time from fin folds</a> that run along the body and end at the tail fin. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=444&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=444&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=444&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=558&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=558&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486459/original/file-20220926-20-47e0ha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=558&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Tujiaaspis</em> fossil (left) and drawing showing its main features. Note the heavy rows of scales that define the lateral ‘fin fold’ area along the body, right down to the tail.</span>
<span class="attribution"><span class="source">Zhikun Gai et al.</span></span>
</figcaption>
</figure>
<h2>When was the first radiation of the jawed fishes?</h2>
<p>Finally, all these discoveries reveal that the first great major “radiation” of the jawed vertebrate (which refers to an explosion in diversity) took place much earlier than anyone imagined. Ivan Sansom from the University of Birmingham was a coauthor on one of the papers. As Sansom notes:</p>
<blockquote>
<p>We’ve had hints of older material previously, but the appearance of clearly defined remains from jawed vertebrates so close to the base of the Silurian suggests jawed and jaw-less fish coexisted for longer than previously thought. There is now evidence for an earlier radiation of sharks and other jawed fish in the Ordovician period.</p>
</blockquote>
<p>The four papers have shaken up the evolutionary tree, and new diagrams are showing revised hypotheses of the relationships between living fishes. Zhu Min informed me it will take many years to complete the studies on the new fossils, with several new species not yet having been described in the papers. </p>
<p>We’ll have to wait patiently for the next exciting discoveries to be announced from these extraordinary fossil sites.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487000/original/file-20220928-14-21xybu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The tiny <em>Xiushanosteus</em> is one of five new fossil fishes described in new research.</span>
<span class="attribution"><span class="source">Heming Zhang</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/190749/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Long receives funding from The Australian Research Council</span></em></p>Spectacular finds of the world’s oldest jawed fishes from China push back the origins of jaws and teeth, and suggest how limbs might have evolved.John Long, Strategic Professor in Palaeontology, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1901512022-09-09T07:35:28Z2022-09-09T07:35:28ZAfrica’s dinosaur discoveries: five essential reads<figure><img src="https://images.theconversation.com/files/483193/original/file-20220907-14-ap277n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Smile if you love dinosaurs as much as Spinosaurus Aegyptiacus loved being a carnivore.</span> <span class="attribution"><span class="source">YuRi Photolife</span></span></figcaption></figure><p>Few prehistoric creatures generate as much excitement and awe as dinosaurs. Whether it’s the “tyrant” T-Rex or a slim-necked Brachiosaurus, people are fascinated by these creatures that dominated landscapes all over the world - including across the African continent - hundreds of millions of years ago.</p>
<p>The dinosaurs are long gone (though we’re still surrounded by their direct descendants, birds). But researchers are still hard at work piecing together the fossil record to create a fuller picture of how dinosaurs lived, walked, ate and raised their young. Their discoveries offer a glimpse into ancient landscapes, helping modern scientists to better understand today’s climates and ecosystems.</p>
<p>The Conversation Africa has showcased a number of dinosaur finds on the continent. Here are five essential reads:</p>
<h2>A rich record</h2>
<p>Africa is widely acknowledged as the birthplace of humankind. But less attention is paid to its incredibly varied fossil record. Many of the planet’s most important life forms originated on the continent: bacteria-like organisms; many dinosaur species and, of course, primates – including humans. Even the rocks on the continent are among the oldest in the world. Some of them date back more than three billion years.</p>
<p>That’s what prompted Julien Benoit to create a syllabus for his palaeontology students that centred African fossil discoveries rather than focusing on finds from elsewhere in the world. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/africas-rich-fossil-finds-should-get-the-air-time-they-deserve-91849">Africa's rich fossil finds should get the air time they deserve</a>
</strong>
</em>
</p>
<hr>
<h2>Hidden in plain sight</h2>
<p>Many museums and universities keep extensive fossil collections. Their contents have been studied, labelled and catalogued. Sometimes, however, they hold secrets that can only be uncovered through a combination of scientific hunch and cutting-edge technology. That’s how Kimberley E.J. Chapelle discovered and described an entirely new species: <em>Ngwevu intloko</em> (“grey skull” in isiXhosa).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-fossil-hidden-in-plain-sight-in-south-africa-turns-out-to-be-a-new-dinosaur-121597">A fossil hidden in plain sight in South Africa turns out to be a new dinosaur</a>
</strong>
</em>
</p>
<hr>
<h2>A giant African dinosaur</h2>
<p>Researchers are constantly rewriting the fossil record thanks to new discoveries. Dinosaurs’ fossilised footprints are a useful tool for this work, as evidenced by a – literally – gigantic find in Lesotho. </p>
<p>It was previously thought that ancient southern African landscapes were dominated by small and agile two-legged carnivorous dinosaurs called theropods. But Lara Sciscio and her colleagues’ study in Lesotho unexpectedly revealed that very large carnivorous dinosaurs with an estimated body length of between 8 and 9 metres (or 26 feet) – that’s a two-storey building or two adult rhinos nose to tail – lived in the region too.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-giant-dinosaur-that-roamed-southern-africa-200-million-years-ago-86004">Meet the giant dinosaur that roamed southern Africa 200 million years ago</a>
</strong>
</em>
</p>
<hr>
<h2>Footprint finds</h2>
<p>Still on the subject of footprints, it turns out that fossilised dinosaur prints hold incredible detail about more than just the size and shape of the creature that made them. As Miengah Abrahams explains, they can reveal what organism made the tracks – different animals have different footprint shapes. They offer clues to the creature’s behaviour and may even contain evidence of what sort of environment dinosaurs roamed – did they sink into wet sand, or were they standing firmly on dry gravel?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/footprints-take-science-a-step-closer-to-understanding-southern-africas-dinosaurs-185480">Footprints take science a step closer to understanding southern Africa's dinosaurs</a>
</strong>
</em>
</p>
<hr>
<h2>A toothy morsel</h2>
<p>Moving from feet to teeth: dinosaurs’ chompers hold important clues to their lives, diets and how they moved across landscapes. That’s why Femke Holwerda ventured to the Kem Kem beds, a geological formation in North Africa, to seek out fossil dinosaur teeth. Her discoveries allowed her to create a fuller picture of the long-necked, plant-eating (herbivorous) dinosaurs, called sauropods, from the Early Cretaceous period of North Africa.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-we-learned-from-dinosaur-teeth-in-north-africa-130894">What we learned from dinosaur teeth in North Africa</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/190151/count.gif" alt="The Conversation" width="1" height="1" />
The African continent is a rich repository for dinosaur fossils, including teeth and track marks.Natasha Joseph, Commissioning EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1849422022-06-16T19:54:25Z2022-06-16T19:54:25ZNew Zealand should celebrate its remarkable prehistoric past with national fossil emblems – have your say!<figure><img src="https://images.theconversation.com/files/468888/original/file-20220615-19-d579ne.jpg?ixlib=rb-1.1.0&rect=49%2C0%2C5472%2C3604&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Trilobites similar to those above have been found in 505 million-year-old rocks in New Zealand.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>It’s not often New Zealanders admit Australia is onto a good thing. Our long-running trans-Tasman rivalry usually revolves around accusing Australians of stealing national cultural icons like Phar Lap, Pavlova or Crowded House.</p>
<p>But I have to admit that when it comes to championing palaeontology (the study of fossils and what they can teach us about our biological heritage), the Australians have a good thing going.</p>
<p>Taking an idea that originated in America, many Australian states in recent decades have started <a href="https://theconversation.com/australia-needs-more-state-fossil-emblems-but-let-the-public-decide-46930">adopting fossil emblems</a> (alongside animal, floral, marine and mineral ones) that epitomise the natural history of each region. </p>
<p>In turn, these emblems can help promote fossil tourism, educational outreach and awareness of the need for fossil protection strategies.</p>
<p>Western Australia chose the 380 million-year-old Devonian fish <em>Mcnamaraspis kaprios</em>, while New South Wales picked a similarly aged fish, <a href="https://www.resourcesandgeoscience.nsw.gov.au/miners-and-explorers_old/geoscience-information_old/nsw-state-emblems/nsw-state-fossil-emblem"><em>Mandageria fairfaxi</em></a>. South Australia adopted the 550 million-year-old <a href="https://www.abc.net.au/news/2017-02-15/reg-sprigg-recognised-honoured-with-sa-fossil-emblem-spriggina/8271586"><em>Spriggina floundersi</em></a> from the dawn of complex life – the first animal in the fossil record whose left and right sides mirrored each other, like ours do today. </p>
<p>The Australian Capital Territory picked the 545 million-year-old brachiopod <a href="https://artsandculture.google.com/story/a-c-t-fossil-emblem/twKCTqZZczzjKA"><em>Atrypa duntroonensis</em></a>, while a public vote in Victoria chose the 125 million-year-old giant amphibian <a href="https://museumsvictoria.com.au/melbournemuseum/state-fossil-emblem/"><em>Koolasuchus cleelandi</em></a>. Queensland is currently holding a public vote to pick an emblem from <a href="https://campaigns.premiers.qld.gov.au/fossilemblem/">12 candidates</a> that include dinosaurs, giant marine reptiles, an amphibian, a crocodile, a <a href="https://australian.museum/learn/species-identification/ask-an-expert/what-is-a-monotreme/">monotreme</a>, a plant and a sea lily.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469095/original/file-20220615-12840-wopa3j.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Skull of a shark-toothed dolphin. This large predator lived about 25 million years ago in what is now modern-day southern New Zealand.</span>
<span class="attribution"><span class="source">Mike Dickison/Wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Aotearoa’s rich fossil record</h2>
<p>Aotearoa New Zealand also has a rich fossil record that palaeontologists have used to unlock the evolution of our taonga (treasured) species and their unique whakapapa (lineage), in some cases stretching back tens to hundreds of millions of years. </p>
<p>In spite of this, there’s a distinct shortfall in palaeontological expertise and funding, which is affecting our ability to study and protect the local fossil record.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-did-ancient-moa-survive-the-ice-age-and-what-can-they-teach-us-about-modern-climate-change-183350">How did ancient moa survive the ice age – and what can they teach us about modern climate change?</a>
</strong>
</em>
</p>
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<p>Nonetheless, New Zealand’s fossils have captured the public imagination, such as the recently discovered 16-19 million-year-old giant Catriona’s shelduck (<a href="https://nzbirdsonline.org.nz/species/catrionas-shelduck"><em>Miotadorna catrionae</em></a>) from St Bathans. Fossils can also inspire future generations through interactive museum displays, outreach and volunteering on fossil digs. </p>
<p><a href="https://www.sciencelearn.org.nz/search?term=fossil">Educational resources</a> can be developed around our unique fossils to teach young New Zealanders how plants and animals evolved in response to the country’s dynamic geological and climatic history. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468895/original/file-20220615-14-zrdu9m.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s impression of <em>Kaiwhekea katiki</em> to scale. The near-complete skeleton of this 75 million-year-old plesiosaur can be seen at Otago Museum.</span>
<span class="attribution"><span class="source">Wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Fossil tourism</h2>
<p>Emblems can also help teach us about the plight and importance of fossils. Newly exposed sites are not being excavated by experts, while other sites are eroding before our eyes. The potential information those sites hold is lost. </p>
<p>While fossil collection by amateurs provides some information, data retention is often substandard, and amateur collection can destroy small sensitive sites. Numerous moa bones, often illegally collected, still come up for sale despite the best efforts to <a href="https://www.rnz.co.nz/news/political/420317/trade-in-moa-bones-would-be-banned-under-proposed-new-rules">stop this practice</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-new-method-of-extracting-ancient-dna-from-tiny-bones-reveals-the-hidden-evolutionary-history-of-new-zealand-geckos-180327">A new method of extracting ancient DNA from tiny bones reveals the hidden evolutionary history of New Zealand geckos</a>
</strong>
</em>
</p>
<hr>
<p>In a post-pandemic world, promoting sustainable tourism is more important than ever. Many regions are uniquely suited to fossil tourism, such as <a href="https://www.waitomocaves.com/">Waitomo</a> and the <a href="https://www.oparara.co.nz/history-of-the-oparara">West Coast</a>. North Otago is already home to the <a href="https://www.whitestonegeopark.nz/">Waitaki Whitestone Geopark</a>, which promotes the geological and fossil history of the region. </p>
<p>Fossil tourism could also be developed at <a href="https://theconversation.com/proposal-to-mine-fossil-rich-site-in-new-zealand-sparks-campaign-to-protect-it-118505">Foulden Maar</a>, a 23 million-year-old lake deposit near Middlemarch in Central Otago, which the public fought to project from mining. It could house a museum and research facilities, and offer opportunities for people to collect fossils for themselves (as happens at <a href="https://www.kronosauruskorner.com.au/">Kronosaurus Korner</a> in Queensland) or volunteer on digs (as they can at the <a href="https://www.australianageofdinosaurs.com/">Australian Age of Dinosaurs</a>).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468893/original/file-20220615-12-7m0rlx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Skull of the mosasaur <em>Prognathodon overtoni</em> that Joan Wiffen discovered. This fearsome predator ruled the oceans of the Late Cretaceous.</span>
<span class="attribution"><span class="source">Lloyd Homer/GNS Science</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Time to choose</h2>
<p>So, what should New Zealanders choose for their fossil emblem? Should we pick something flashy like the pouakai/<a href="https://nzbirdsonline.org.nz/species/haasts-eagle">Haast’s eagle</a> (<em>Aquila moorei</em>) whose ancestor, the smallest eagle in the world, arrived in Aotearoa only about 2.5 million years ago and rapidly evolved into the world’s largest?</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=775&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=775&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=775&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=974&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=974&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468894/original/file-20220615-15-mupsdz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=974&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s reconstruction of pouakai/Haast’s eagle (<em>Aquila moorei</em>), the largest eagle in the world, <strong>which</strong> went extinct only 500-600 years ago.</span>
<span class="attribution"><span class="source">Paul Martinson/Te Papa</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>What about the 75 million-year-old <a href="https://www.otago.ac.nz/geology/research/paleontology/kaiwhekea-katiki.html">plesiosaur</a> <em>Kaiwhekea katiki</em> or the <a href="https://www.otago.ac.nz/geology/research/paleontology/squalodontidae.html">shark-toothed dolphin</a> that capture my children’s attention?</p>
<p>We could agree that size does matter and choose the 55-60 million-year-old <a href="https://nzbirdsonline.org.nz/species/bices-penguin">giant Bice penguin</a> (<em>Kumimanu biceae</em>) or moa nunui/<a href="https://nzbirdsonline.org.nz/species/south-island-giant-moa">South Island giant moa</a> (<em>Dinornis robustus</em>). At the other end of the scale, how about the smallest fossils like 505 million-year-old <a href="https://teara.govt.nz/en/photograph/8297/trilobite-rock">trilobites</a>, some of our oldest fossils?</p>
<p>Should we consider historical value, like the first theropod dinosaur or one of the mosasaurs (such as <em>Prognathodon overtoni</em>) that pioneering fossil hunter <a href="https://teara.govt.nz/en/biographies/6w4/wiffen-joan">Joan Wiffen</a> discovered? Or should scientific value prevail, like the living pūpū whakarongotaua/<a href="https://en.wikipedia.org/wiki/Placostylus_ambagiosus">flax snail</a> (<em>Placostylus ambagiosus</em>), whose abundant fossil shells are teaching us a lot about the impacts of climate change and human settlement?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/proposal-to-mine-fossil-rich-site-in-new-zealand-sparks-campaign-to-protect-it-118505">Proposal to mine fossil-rich site in New Zealand sparks campaign to protect it</a>
</strong>
</em>
</p>
<hr>
<p>I’m forming a committee of palaeontologists from across New Zealand to decide on a shortlist to put to a public vote. We would welcome input about what fossils to consider, whether we should have a single emblem representing New Zealand, or regional emblems, and even a yearly competition like the sometimes controversial <a href="https://www.birdoftheyear.org.nz/">Bird of the Year</a>.</p>
<p>So get your iwi, whanau, school and local museum involved, lobby your local politicians and let us know what you think at <em>nzfossilemblem@otago.ac.nz</em></p><img src="https://counter.theconversation.com/content/184942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nic Rawlence receives funding from the Royal Society of New Zealand Marsden Fund. </span></em></p>Australia has them, so why doesn’t New Zealand have national or regional fossil emblems? A campaign to change that kicks off today.Nic Rawlence, Senior Lecturer in Ancient DNA, University of OtagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1801952022-03-31T15:06:36Z2022-03-31T15:06:36ZTraces of giant prehistoric crocodiles discovered in northern British Columbia<figure><img src="https://images.theconversation.com/files/455165/original/file-20220330-4833-s6k8hg.jpg?ixlib=rb-1.1.0&rect=0%2C20%2C4600%2C2823&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Today's crocodiles are quite similar to their prehistoric ancestors, if a bit on the smaller side.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/traces-of-giant-prehistoric-crocodiles-discovered-in-northern-british-columbia" width="100%" height="400"></iframe>
<p>Giant crocodiles once roamed northeastern British Columbia. A recently published article in <em>Historical Biology</em> features <a href="https://doi.org/10.1080/08912963.2022.2043294">the first detailed trace fossil evidence ever reported of giant crocodylians</a>. The sites are from the Peace Region of northeastern British Columbia, north of Tumbler Ridge. </p>
<p>The trace fossils include <a href="https://doi.org/10.17159/sajs.2021/8830">swim traces</a>, made when the crocodiles were scraping the muddy bottoms of lakes and river channels with their claws. Some of these swim traces showed remarkable detail, including parallel striations that represent scale patterns on the crocodiles’ feet.</p>
<p>While the Tumbler Ridge area has become <a href="https://www.tumblerridgegeopark.ca/index.php/fossil-sites/">well known for its dinosaur tracks</a>, there is something special about crocodiles. Unlike dinosaurs, they survived, and still have <a href="https://www.livescience.com/38596-mesozoic-era.html">not changed substantially since the Mesozoic</a>.</p>
<p>In 2020, a crane company donated time and personnel to recover <a href="https://www.trmf.ca/news/a-dramatic-close-to-2020-field-season">four large blocks containing some of the finest examples of these tracks and traces</a>. They were transported to <a href="https://www.trmf.ca/">the Tumbler Ridge Museum</a>, where they are securely stored and will be incorporated into future exhibits. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a photo of crocodile swim traces which look like raised welts on rock" src="https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=723&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=723&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455162/original/file-20220330-19-apa9iy.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=723&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An example of giant crocodile swim traces made by a crocodile’s claws scraping the bottom of a river channel, showing scale striations.</span>
<span class="attribution"><span class="source">(C. Helm)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Ancient giants</h2>
<p>The tracks and traces we examined are in the age range of 95–97 million years from the <a href="https://www.britannica.com/science/Cretaceous-Period#:%7E:text=Cretaceous%20Period%2C%20in%20geologic%20time,the%20Tertiary%20Period%20was%20divided">Cretaceous Period</a>. The tracks included ankylosaurs, ornithopods and turtles.</p>
<p>The size of the crocodiles can be estimated from <a href="https://doi.org/10.1016/j.cretres.2021.104967">the distance between their claw impressions</a>. We used this distance to estimate a total body length of about nine metres, and possibly as much as 12 metres. This was corroborated by our identification of a partial track, 75 centimetres long, which allowed for a similar length estimate of close to nine metres. </p>
<p>A crocodile of such prodigious size would have weighed around five tonnes, and would probably have been a top predator. By comparison, the record length of crocodiles living today is about six metres.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large mother crocodile waits next to her babies on a rock" src="https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455160/original/file-20220330-13-3ma5w3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Today’s crocodiles are significantly smaller than their prehistoric ancestors.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Gigantism in crocodiles has been <a href="https://doi.org/10.1080/02724634.1999.10011201">reported several times in the fossil record</a>. In North America, the oldest body fossil evidence of giant crocodiles is of <em>Deinosuchus</em> at about 82 million years, <a href="http://www.sci-news.com/paleontology/deinosuchus-schwimmeri-08730.html">estimated to have been between eight to 12 metres long</a>. <em>Deinosuchus</em> has been recorded from the United States and Mexico, but never from Canada. </p>
<p>The large swim traces from north of Tumbler Ridge may represent a precursor to <em>Deinosuchus</em>, that lived at least 13 million years before the previously reported first appearance of giant crocodiles in North America. </p>
<h2>Tracking enviromental changes</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="alt" src="https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=676&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=676&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=676&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=850&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=850&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455161/original/file-20220330-4905-14ijpzm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=850&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">3D photogrammetry image showing a trackway made by a juvenile ankylosaur on the left, and on the right a hybrid between a crocodile track and swim trace; horizontal and vertical scales are in metres.</span>
<span class="attribution"><span class="source">(C.Helm)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The environment consisted of a low-lying delta-plain with shallow lakes, river channels and vegetated wetlands, situated about 100 kilometres inland from the shoreline of <a href="https://www.collectionscanada.gc.ca/eppp-archive/100/205/301/ic/cdc/ancientseas/uppercret.htm">the Western Interior Seaway</a> that linked the Gulf of Mexico with the Arctic Ocean. </p>
<p>It was possible to document multiple episodes of flooding and emergence, which determined whether and when animals walked or swam. This helped explain the variety of tracks and traces that were identified.</p>
<p>These findings follow our discovery of <a href="https://doi.org/10.1016/j.cretres.2021.104967">112 million-year-old swim traces</a>, made by much smaller crocodylians (between one and two metres long) within the <a href="https://www.tumblerridgegeopark.ca">Tumbler Ridge UNESCO Global Geopark</a>. Our familiarity with the nature of the exceptionally well-preserved traces from near Tumbler Ridge led directly to the first identification of crocodile swim traces in Africa.</p>
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<strong>
Read more:
<a href="https://theconversation.com/fossil-track-sites-tell-the-story-of-ancient-crocodiles-in-southern-africa-134410">Fossil track sites tell the story of ancient crocodiles in southern Africa</a>
</strong>
</em>
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<p>The co-existence of traces made by <a href="https://www.britannica.com/animal/dinosaur/Ankylosauria">walking ankylosaurs</a> and swimming crocodiles on a single surface was intriguing and unprecedented in the fossil record. One of the ankylosaur trackways is the smallest thus far described from the region. It comprised tracks only 10 centimetres wide, presumably made by a juvenile.</p><img src="https://counter.theconversation.com/content/180195/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Guy Plint receives funding from the Natural Sciences and Engineering Research Council of Canada, Discovery Grant Program.</span></em></p><p class="fine-print"><em><span>Charles Helm does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>While crocodiles are not native to Canada, fossil traces have been found in northern British Columbia that indicate that during the Cretaceous Period, giant crocodiles roamed.Guy Plint, Professor, Earth Sciences, Western UniversityCharles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1736342022-02-01T13:14:21Z2022-02-01T13:14:21ZDid male and female dinosaurs differ? A new statistical technique is helping answer the question<figure><img src="https://images.theconversation.com/files/443225/original/file-20220128-23-12zgv3p.jpg?ixlib=rb-1.1.0&rect=2%2C14%2C1950%2C1159&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How can researchers tell if male and female dinosaurs, like the stegosaur, were different?</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Journal.pone.0138352.g001A.jpg#/media/File:Journal.pone.0138352.g001A.jpg">Susannah Maidment et al. & Natural History Museum, London</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>In most animal species, <a href="https://doi.org/10.2307/2407393">males and females differ</a>. This is true for people and other mammals, as well as many species of birds, fish and reptiles. But what about dinosaurs? In 2015, I proposed that variation found in the iconic back plates of stegosaur dinosaurs was <a href="https://doi.org/10.1371/journal.pone.0123503">due to sex differences</a>.</p>
<p>I was surprised by how strongly some of my colleagues <a href="https://doi.org/10.1017/pab.2016.51">disagreed</a>, arguing that differences between sexes, called sexual dimorphism, <a href="https://doi.org/10.2307/2407393">did not exist in dinosaurs</a>.</p>
<p><a href="https://scholar.google.com/citations?user=umU9KBMAAAAJ&hl=en&oi=ao">I am a paleontologist</a>, and the debate sparked by my 2015 paper has made me reconsider how researchers studying ancient animals use statistics. </p>
<p>The limited fossil record makes it hard to declare if a dinosaur was sexually dimorphic. But I and some others in my field are beginning to <a href="https://doi.org/10.1038/d41586-019-00857-9">shift away from traditional black-or-white statistical thinking</a> that relies on p-values and statistical significance to define a true finding. Instead of only looking for yes or no answers, we are beginning to consider the estimated magnitude of sexual variation in a species, the degree of uncertainty in that estimate and how these measures compare to other species. This approach offers a more nuanced analysis to challenging questions in paleontology as well as many other fields of science.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A very colorful duck standing next to a drab brown duck." src="https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443076/original/file-20220127-9640-1ercxvu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In many species, like these mandarin ducks, males (left) and females (right) look very different.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Pair_of_mandarin_ducks.jpg">Francis C. Franklin via WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Differences between males and females</h2>
<p><a href="http://dx.doi.org/10.1007/978-3-319-47829-6_433-1">Sexual dimorphism</a> is when males and females of a certain species differ on average in a particular trait – not including their reproductive anatomy. Classic examples are how male deer have antlers and male peacocks have flashy tail feathers, while the females lack these traits.</p>
<p>Dimorphism can also be subtle and unflashy. Often the difference is one of degree, like differences in the average body size between males and females – as in <a href="https://doi.org/10.1007/s12110-012-9130-3">gorillas</a>. In these modest cases, researchers use statistics to determine whether a trait differs on average between males and females.</p>
<h2>The dinosaur dilemma</h2>
<p>Studying sexual dimorphism in extinct animals is fraught with uncertainty. If you and I independently dig up similar fossils of the same species, they are inevitably going to be slightly different. These differences could be due to sex, but they could also be driven by age – <a href="https://www.worldcat.org/title/avian-anatomy-integument/oclc/603445440&referer=brief_results">young birds are fuzzy, adult birds are sleek</a>. They could also be due to genetics unrelated to sex, like eye color in humans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two drawings of dinosaurs showing different shaped horns and frills." src="https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=520&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=520&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=520&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=653&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=653&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437461/original/file-20211214-15-1gmw3ot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=653&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s possible that variation among individual dinosaurs of the same species could be due to sexual dimorphism, but there are rarely good enough samples to assert so using traditional statistics.</span>
<span class="attribution"><span class="source">James Ormiston</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>If paleontologists had thousands of fossils to study of every species, the many sources of biological variation wouldn’t matter as much. Unfortunately, the <a href="https://doi.org/10.1002/bies.201700167">ravages of time</a> have left the fossil record painfully incomplete, often with less than a dozen good specimens for large, extinct vertebrate species. Additionally, there is currently no way to identify the sex of an individual fossil except in rare cases where obvious clues exist, like <a href="https://doi.org/10.1126/science.1110578">eggs preserved within the body cavity</a>. </p>
<p>So where does all this leave the debate on whether male and female dinosaurs had differences within traits? On the one hand, birds – which are direct descendants of dinosaurs – <a href="https://doi.org/10.1098/rspb.1998.0308">commonly show sexual dimorphism</a>. So do <a href="https://doi.org/10.18475/cjos.v45i1.a12">crocodilians</a>, dinosaurs’ next closest living relatives. Evolutionary theory also predicts that, since dinosaurs reproduced with sperm and egg, there would be a <a href="https://doi.org/10.1016/j.tree.2011.12.006">benefit to sexual dimorphism</a>.</p>
<p>These things all suggest that dinosaurs likely were sexually dimorphic. But in science you need to be quantitative. The challenge is that there is little in the way of <a href="https://doi.org/10.1017/pab.2016.51">statistically significant</a> analyses of the fossil record to support dimorphism. </p>
<h2>Statistical shifts</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A line graph showing two peaks." src="https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=396&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=396&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443057/original/file-20220127-6424-dz34sy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=396&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Very large sex differences can create a bimodal distribution that looks like two distinct groupings of a certain measurement.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Bimodal.png">Maksim via WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>There are a couple of ways paleontologists could test for sexual dimorphism. They could look to see if there are statistically significant differences between fossils from presumed males and females, but there are very few specimens where researchers <a href="https://doi.org/10.1073/pnas.0708903105">know the sex</a>. Another method is to see whether there are two distinct groupings of a trait, called a bimodal distribution, which could suggest a difference between males and females.</p>
<p>To tell whether a perceived difference between two groups is true, scientists have traditionally used a tool called the p-value. P-values quantify the probability of a result being due to random chance. If a p-value is low enough, the result is deemed “statistically significant” and considered unlikely to have happened by chance.</p>
<p>But p-values can be heavily influenced by sample size and the design of the study, in addition to the actual degree of sexual dimorphism. Because of the very small sample size of fossils, relying on this statistical technique makes it exceedingly difficult to categorically proclaim what dinosaur species were dimorphic. </p>
<p>The weakness of the black-or-white approach that focuses solely on whether a result is statistically significant has led to hundreds of scientists <a href="https://doi.org/10.1038/d41586-019-00857-9">calling to abandon significance testing with p-values</a> in favor of something called <a href="https://doi.org/10.1111/j.1469-185X.2007.00027.x">effect size statistics</a>. Using this approach, researchers would simply report the measured difference between two groups and the uncertainty in that measurement.</p>
<h2>Effect size statistics</h2>
<p>I have begun to apply effect size statistics in <a href="https://doi.org/10.1093/biolinnean/blaa105">my research on dinosaurs</a>. My colleagues and I compared sexual dimorphism in body size between three different dinosaurs: the duck-billed <em>Maiasaura</em>, <em>Tyrannosaurus rex</em> and <em>Psittacosaurus</em>, a small relative of <em>Triceratops</em>. None of these species would be expected to show statistically significant size differences between males and females according to p-values. But that approach does not capture the nature of the variation within these species. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cast of a duck billed dinosaur fossil skeleton." src="https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443567/original/file-20220131-15-3xspkd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Using effect size statistics, researchers were able to determine that the duck-billed dinosaur <em>Maiasaura</em> showed a larger amount of dimorphism with the least uncertainty in that estimate compared to other dinosaurs.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Maiasaura#/media/File:Maiasaura_peeblesorum_cast_-_University_of_California_Museum_of_Paleontology_-_Berkeley,_CA_-_DSC04688.JPG">Daderot via WikimediaCommons</a></span>
</figcaption>
</figure>
<p>When we instead used effect size statistics, we were able to estimate that male and female <em>Maiasaura</em> demonstrate a greater difference in body mass compared to the other two species and that we had a higher confidence in this estimate as well. A few of the characteristics within the data helped reduce the uncertainty. First, we had a large number of <em>Maiasaura</em> fossils, from individuals of various ages. These bones very nicely fit with trajectories of how size changes as an individual grows from juvenile to adult, so we could control for differences due to age and instead focus on differences due to sex.</p>
<p>Additionally, the <em>Maiasaura</em> fossils all come from a <a href="https://doi.org/10.1017/pab.2015.19">single bone bed</a> of individuals that died in the same place at the same time. This means that variation between individuals is likely not due to them being different species from different regions or time periods. </p>
<p>If my colleagues and I had approached the problem expecting a yes or no answer on whether males and females differed in size, we would have completely missed all of these intricacies. Effect size statistics allow researchers to produce much more nuanced and, I think, informative results. It is almost as much a difference in the philosophical approach to science as it is a mathematical one.</p>
<p>Studying dinosaur dimorphism is not the only place p-values create issues. Many fields of science, including <a href="https://theconversation.com/the-replication-crisis-is-good-for-science-103736">medicine and psychology</a>, are having similar <a href="https://doi.org/10.1080/00031305.2018.1543137">debates about issues in statistics</a> and a worrying problem of <a href="https://doi.org/10.1371/journal.pmed.0020124">unrepeatable studies</a>.</p>
<p>Embracing uncertainty in data – rather than looking for black-or-white answers to questions like whether male and female dinosaurs were sexually dimorphic – can help elucidate dinosaur biology. But this shift in thinking may be felt far and wide across the sciences. A careful consideration of problems within statistics could have deep impacts across many fields.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/173634/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evan Thomas Saitta does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The lack of large numbers of fossils makes it hard to study sexual dimorphism in dinosaurs. But a new statistical approach offers insight into this question and others across science.Evan Thomas Saitta, Postdoctoral Scholar in Paleontology, University of ChicagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1688392021-10-13T19:12:42Z2021-10-13T19:12:42ZHumans are driving animals and plants to the edge. But are we really heading into a mass extinction?<figure><img src="https://images.theconversation.com/files/426080/original/file-20211012-24-aqip4l.jpg?ixlib=rb-1.1.0&rect=53%2C26%2C5937%2C3961&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock/Nick Greaves</span></span></figcaption></figure><p>It is now common to refer to the current biodiversity crisis as the sixth mass extinction. But is this true? Are we in the middle of an event on the same scale as the five ancient mass extinctions Earth has experienced?</p>
<p>Humans are indeed driving animals and plants to extinction. Land clearance, habitat modification and, above all, climate change are all placing biodiversity under stress. </p>
<p>Many species have died out since the arrival of humans and many more are threatened. </p>
<p>But to answer this question fully, we have to look at the rates at which species were going extinct before the appearance of humans and compare it to today’s rate.</p>
<p>Life on Earth has diversified from a single cell more than 3.7 billion years ago to the <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001127">estimated 8.7 million species</a> alive today.</p>
<p>But as I describe in my book <a href="https://www.cambridge.org/core/books/extinctions/A4B6AA42F403802A0F9D99F64ECF583E">Extinctions: living and dying in the margin of error</a>, this journey has been a roller coaster ride. There have been times when biodiversity exploded with many new species evolving relatively quickly. Conversely, there have been extremely short intervals of time when biodiversity crashed in a mass extinction. </p>
<p>The scale of biodiversity loss in a mass extinction is extraordinary. In the five mass extinctions on Earth, estimates of species loss range from around 70% at the end of the Cretaceous up to 95% at the end of the Permian, the <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.1994.0045">largest of the mass extinctions</a>. </p>
<figure class="align-center ">
<img alt="The Gubbio section, found in Italy, represents a complete record of the end-of-Cretaceous mass extinction." src="https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425820/original/file-20211011-25-auc2tn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Gubbio section, found in Italy, represents a complete record of the end-of-Cretaceous mass extinction. The exact instant when about 70% of species went extinct is marked by the cleft running diagonally across the image.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Each of these events resulted in a wave of extinctions washing across all of the planet’s ecosystems. Reefs were wiped out, dinosaurs disappeared, insect species were decimated and plants went through massive upheavals. It took up to a million years for ecosystems to recover from a mass extinction.</p>
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Read more:
<a href="https://theconversation.com/ocean-ecosystems-take-two-million-years-to-recover-after-mass-extinction-new-research-124328">Ocean ecosystems take two million years to recover after mass extinction – new research</a>
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<h2>Ancient and modern extinction rates</h2>
<p>Estimating prehuman extinction rates from the somewhat patchy fossil record is fraught. Nevertheless, researchers have <a href="https://www.nature.com/articles/nature09678">managed do it</a>, albeit using only vertebrate fossils. </p>
<p>Their estimate suggests prior to the arrival of humans, vertebrate species were going extinct at the rate of about two per million species lost every year. </p>
<p>In 2015, another research team took this estimate and compared it with <a href="https://pubmed.ncbi.nlm.nih.gov/26601195/">present day vertebrate extinction rates</a>. They found vertebrates are going extinct 53 times faster today than they were before humans arrived.</p>
<p>If the increase in extinction rates recorded in vertebrates is on a similar scale across the planet’s entire biota, humans have triggered a significant rise in the rate of species going extinct. </p>
<p>But is that enough to consider our current biotic crisis a mass extinction?</p>
<figure class="align-center ">
<img alt="Trilobites once filled the world's oceans but died out at the end of the Permian." src="https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426088/original/file-20211013-23-1jrxqxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Trilobites were ancient arthropods that filled the world’s oceans from the early Cambrian, some 520 million years ago, until the mass extinction at the end of the Permian, 252 million years ago.</span>
<span class="attribution"><span class="source">Shutterstock/Tami Freed</span></span>
</figcaption>
</figure>
<p>To answer that question, we need to consult the <a href="https://www.iucnredlist.org/">Red List</a> run by the International Union for the Conservation of Nature (<a href="https://www.iucn.org/">ICUN</a>). This list is an attempt to assess the threat of extinction of all known species by assigning each to a category of descending threat: extinct or extinct in the wild, severe threat of extinction, threatened and so on. </p>
<h2>Are we there yet?</h2>
<p>A glance across the Red List confirms that, as with the ancient mass extinctions, today’s species loss affects the entire biosphere. However, the situation changes when we compare the current level of extinction with those from the big five mass extinctions. </p>
<figure class="align-left ">
<img alt="A fossil of a plant that went extinct 550 million years ago." src="https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426110/original/file-20211013-17-1vj5w5g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This fossil (Arborea arborea) is part of the Ediacaran fauna from South Australia which went extinct about 550 million years ago.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As noted above, the loss of species during the ancient mass extinctions is massive. Data from the Red List suggest we haven’t come close to those. For example, the Red List assigns only 1.46% of mammal species to the extinct or extinct in the wild categories. It considers less than 1% of amphibian species are extinct or extinct in the wild. For insects, it’s 0.65%, bivalves 4% and corals 0%. This level of species loss isn’t close to the losses recorded in the fossil record.</p>
<p>While the rate at which species are going extinct has risen and the entire ecosystem is affected, we have, at the moment at least, only low levels of extinction. </p>
<p>Unfortunately, species extinction levels show only part of the problem. To see the full extent of the crisis, we need to add the species the Red List considers to be under threat of extinction to those already extinct. </p>
<p>When we do, the picture changes. Taken together, the percentage of mammals that are extinct or under threat of extinction rises from 1.46% to 23.48%, amphibian numbers rise to 33.56%, insects to 19.23% and corals to 26.85%. These numbers demonstrate the true scale of the threat facing the planet’s biosphere.</p>
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<strong>
Read more:
<a href="https://theconversation.com/animals-are-disappearing-from-forests-with-grave-consequences-for-the-fight-against-climate-breakdown-new-research-124746">Animals are disappearing from forests, with grave consequences for the fight against climate breakdown – new research</a>
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<p>I don’t like referring to today’s crisis as a mass extinction because it allows us to focus entirely on extinction levels, and they are low. Others have coined a new term to reflect the fact that although many species are extinct, there are many more threatened with extinction: <a href="https://www.science.org/doi/10.1126/science.1251817">defaunation</a>. </p>
<p>Defaunation better describes the crisis unfolding in the planet’s biosphere. To avoid a slide into a full-blown mass extinction, we must not allow defaunation to continue. We know how to do this: reduce emissions, protect vulnerable ecosystems and regenerate degraded ones.</p><img src="https://counter.theconversation.com/content/168839/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Hannah is affiliated with NZ Labour party</span></em></p>While current extinction rates remain lower than during previous mass extinction events, the number of species under threat of dying out is growing, reflecting the true scale of loss.Michael Hannah, Associate Professor, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1687932021-10-03T12:58:44Z2021-10-03T12:58:44ZFinding a rare fossilized comb jelly reveals new gaps in the fossil record<figure><img src="https://images.theconversation.com/files/423512/original/file-20210928-28-zx3gwt.jpg?ixlib=rb-1.1.0&rect=0%2C14%2C1598%2C1048&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The bodies of comb jellies like Mertensia ovum are soft, meaning they rarely fossilize.</span> <span class="attribution"><a class="source" href="http://coldwater.science/project/ctenophora">(Alexander Semenov)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>They look like jellyfish but they aren’t. They seem inoffensive but are efficient predators — occasionally, they even eat fish. They are gelatinous and very delicate — and extremely rarely do they fossilize! </p>
<p>Ctenophores, also known as comb jellies, are <a href="https://ucmp.berkeley.edu/cnidaria/ctenophora.html">colourful, translucent animals, that drift through oceanic waters</a>. Unlike jellyfish, ctenophores don’t have stinging cells, and typically capture prey using long, sticky tentacles. </p>
<p>Our research describing a fossilized ctenophore from Eastern Canada, published recently in <em>Scientific Reports</em>, suggests that <a href="https://doi.org/10.1038/s41598-021-98362-5">our creature was a very late survivor from the very dawn of animals</a>. It also means that a very controversial idea about early animal evolution can’t be rejected by the fossil record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photograph of a lake and cluffs" src="https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423683/original/file-20210928-13-1nr5tkz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The new ctenophore fossil, <em>Daihuoides jakobvintheri</em>, was found in the fine sediments from Miguasha cliffs along the Restigouche River in the Gaspé Peninsula, eastern Québec.</span>
<span class="attribution"><span class="source">(Johanne Kerr)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Common today but rare as fossils</h2>
<p>There are approximately <a href="https://faculty.washington.edu/cemills/Ctenolist.html">200 species of living ctenophores</a>, and many are locally abundant. Some well-known modern comb jellies include the sea gooseberry (<em>Pleurobrachia pileus</em>) found in the open water in the northern Atlantic Ocean, the North Sea, the Baltic Sea and the Black Sea, and the ribbon-like Venus girdle (<em>Cestum veneris</em>) that can be seen in tropical and subtropical oceans worldwide.</p>
<p>However, their delicate bodies generally lack hard parts, meaning very few fossil ctenophores have been preserved and discovered: <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/ctenophora">only about a dozen species have been found globally</a>. Fossilization of these soft-bodied animals requires exceptional conditions such as very rapid burial with very fine sediments in an oxygen-poor aquatic environment, which suppresses the activities of decomposing and scavenging organisms. Other environmental parameters also play an important role in the preservation.</p>
<p>Until the early 1980s, comb jellies were unknown from the fossil record. The first comb jelly fossil to be discovered came from the Early Devonian <a href="https://carnegiemnh.org/tag/hunsruck-slate/">Hunsrück Slate of Germany</a>, deposited some 405 million years ago. </p>
<p>Since then, records of spectacularly preserved early relatives of comb jellies were described from the 518-million-year-old <a href="https://www.geosociety.org/gsatoday/archive/11/2/pdf/i1052-5173-11-2-4.pdf">Chengjiang Biota</a> in southern China, the 505-million-year-old <a href="https://www.burgess-shale.bc.ca/">Burgess Shale of British Columbia in Western Canada</a> and other similar deposits. </p>
<p>In August, two new species of <a href="http://dx.doi.org/10.1016/j.isci.2021.102943">Cambrian comb jellies were also reported from Utah</a>. Our new fossil, named <em>Daihuoides jakobvintheri</em>, adds substantially to this scant record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration showing two possible reconstructions of acomb jelly fossil" src="https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=218&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=218&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=218&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=274&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=274&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423524/original/file-20210928-26-1cohmji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=274&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two alternative life reconstructions of the fossil comb jelly <em>Daihuoides jakobvintheri</em>, (A) as a pelagic animal like modern comb jellies, and resembles a jellyfish, and (B) as a benthic animal, like many Cambrian comb jellies, and resembles a sea anemone.</span>
<span class="attribution"><span class="source">(Scientific Reports)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Strange anatomical symmetry</h2>
<p>Most living ctenophores have a translucent spherical or cylindrical body, frequently showing bright-coloured bioluminescence, vaguely reminiscent of colourful disco mirror balls. Most use a pair of long tentacles, armed with non-venomous sticky cells (colloblasts), to trap small prey and convey it to their mouth on the top of their body. </p>
<p>Ctenophores propel themselves using comb rows: beating hairs (cilia) organized into longitudinal bands. The presence, number and organization of these comb rows are taxonomically important. The single specimen of our fossil <em>Daihuoides</em> reveals a circular disk-shaped body (calyx), approximately six centimetres in diameter, with 18 radiating comb rows, each one distinguished by a clear zigzag pattern. </p>
<p>The presence of comb rows permitted us to identify this fossil as a ctenophore, but their high number was puzzling. This number is unusual in a living ctenophore, but rather common in very ancient Cambrian ctenophores. Cambrian comb jellies from the Chinese Chengjiang fauna, <a href="https://doi.org/10.1016/j.cub.2019.02.036">belonging to the genera <em>Daihua</em>, <em>Xianguangia</em> and <em>Dinomischus</em></a>, share a hexaradiate-based symmetry, meaning being six-fold or a multiple thereof, such as 18-fold.</p>
<h2>Exceptional conditions</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photograph and diagram of the found fossil" src="https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1109&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1109&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1109&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1394&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1394&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423521/original/file-20210928-18-14ssdmx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1394&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The fossil comb-jelly <em>Daihuoides jakobvintheri</em>, showing 18 radially-arranged comb rows.</span>
<span class="attribution"><span class="source">(Scientific Reports)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our new fossil comes from the well-documented <a href="http://dx.doi.org/10.12789/geocanj.2013.40.008">Devonian fossil site from Miguasha</a> along the south coast of the Gaspé Peninsula in Eastern Canada. </p>
<p>It is a <a href="https://whc.unesco.org/en/list/686/">UNESCO World Heritage Site</a> because it preserves an exceptional diversity of early fishes, including a transitional form between fishes and land vertebrates (tetrapods). This trove of fossils, known as the Escuminac assemblage, is 375 million years old — <a href="https://theconversation.com/when-fish-gave-us-the-finger-this-ancient-four-limbed-fish-reveals-the-origins-of-the-human-hand-129072">and was once an estuary near the equator</a>!</p>
<p>Since 1842, more than 21,000 fossil fish belonging to 20 different species have been found. Many of these fossils represent near-complete skeletons with most bones still in place.</p>
<p>In contrast to the plethora of fishes, invertebrates are rare and less diverse. In fact, only 10 species have been found. Most of them only known from a handful of specimens, and are primarily arthropods (hard-bodied invertebrates with jointed legs, represented today by things such as crabs and insects). </p>
<h2>The base of the tree of life</h2>
<p>The Cambrian Explosion refers to the near-simultaneous appearance of the major groups of animals in the fossil record, between 540 and 520 million years ago.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/exquisite-fossil-finds-shed-new-light-on-the-cambrian-explosion-when-oceans-first-filled-with-complex-animal-life-114054">Exquisite fossil finds shed new light on the 'Cambrian explosion', when oceans first filled with complex animal life</a>
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</em>
</p>
<hr>
<p>Before then, animals were very simple and largely microscopic, but in the geological blink of an eye, most of the modern phyla of animals (metazoans) appeared, including arthropods, molluscs and vertebrates. Ctenophores have long been thought to be near the base of the animal tree of life, resembling other primitive forms such as cnidarians (corals and jellyfish). Sponges look primitive because they lack a nervous system and organized tissues, and they only have a few cell types.</p>
<p>Ctenophores and cnidarians, despite their relative simplicity, are much more complex than sponges, so it was traditionally assumed that sponges were at the absolute base of the animal family tree — the “sponges-first hypothesis.” </p>
<p>However, some recent genomic studies have proposed that <a href="https://doi.org/10.1038/nature.2013.12176">comb jellies are actually even lower on the family tree than sponges</a>, a “ctenophores-first” hypothesis. This radical idea remains highly controversial because sponges have been assumed to be more primitive than ctenophores for more than 150 years. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-our-most-distant-animal-relative-a-sponge-or-a-comb-jelly-our-study-provides-an-answer-151889">Is our most distant animal relative a sponge or a comb jelly? Our study provides an answer</a>
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</em>
</p>
<hr>
<p>If true, it could mean that many of the traits ctenophores share with typical animals (such as a nervous system, gut and complex muscles) might have <a href="https://www.quantamagazine.org/comb-jelly-neurons-spark-evolution-debate-20150325/">evolved twice</a>: once in comb jellies and separately in all other animals. </p>
<p>Comb jellies would be true evolutionary aliens compared to all other animals.</p>
<p>In the light of our discovery, we tested whether the anatomy of fossil ctenophores better supports the sponges-first or ctenophores-first hypothesis. Surprisingly, and contrary to a <a href="https://phys.org/news/2019-03-half-a-billion-year-old-fossil-reveals-jellies.html">previous study</a>, the fossils were equally consistent with both ideas.</p>
<h2>Lazarus fossil</h2>
<p>According to the Bible, Jesus restored Lazarus of Bethany to life four days after his death. In paleontology, a “<a href="https://theconversation.com/meet-the-lazarus-creatures-six-species-we-thought-were-extinct-but-arent-50274">Lazarus taxon</a>” is an organism that disappears from the fossil record for a lengthy period, only to reappear much later. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a comb jellyfossil" src="https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423757/original/file-20210929-22-a6zocj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reconstruction of a fossil ctenophore from the Cambrian Period, <em>Ctenorhabdotus capulus</em>, which is some 140 million years older than <em>Daihuoides</em> but still very similar.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Ctenorhabdotus_capulus.jpg">(Apokryltaros/Wikipedia)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Our new fossil ctenophore, <em>Daihuoides</em>, is a perfect example of such a Lazarus taxon and postdates its Cambrian relatives by over a hundred million years. Our creature resembles a primitive type of ctenophore with 18 sets of organs radially arranged. These forms were known from the Cambrian (over 500 million years ago) and then assumed to have gone extinct soon afterwards.</p>
<p><em>Daihuoides</em> shows that these primitive comb jellies survived for a further 140 million years, into the Devonian, approximately 375 million years ago. This discovery demonstrates the huge gaps in the known fossil record, and implies many wonderful fossils are yet to be discovered.</p>
<p><em>Johanne Kerr, researcher at Parc national de Miguasha, co-authored this article.</em></p><img src="https://counter.theconversation.com/content/168793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Cloutier receives funding from Natural Sciences and Engineering Research Council of Canada.</span></em></p><p class="fine-print"><em><span>Christian Klug receives funding from the Swiss National Science Foundation SNSF. </span></em></p><p class="fine-print"><em><span>Mike Lee receives funding from The Australian Research Council (ARC).</span></em></p>Fossilized comb jellies, or ctenophores, are rare because the creatures are almost completely soft-bodied. Rare fossil finds are helping us learn more about ancient animals and evolution.Richard Cloutier, Professor of Evolutionary Biology, Université du Québec à Rimouski (UQAR)Christian Klug, Professor, Curator of the Palaentological Museum, University of ZurichMike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1666602021-08-27T03:21:14Z2021-08-27T03:21:14ZNew Zealand’s fossil record suggests more species lived in warmer waters. But the current rate of warming may break this pattern<figure><img src="https://images.theconversation.com/files/418169/original/file-20210827-15-1cbflxk.jpg?ixlib=rb-1.1.0&rect=84%2C162%2C3844%2C1780&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tom Womack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><figure class="align-right ">
<img alt="Diffedrent types of marine organisms found in New Zealand." src="https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1814&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1814&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418165/original/file-20210827-13-1ysnxbt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1814&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Marine organisms found in New Zealand’s past and present coastal waters.</span>
<span class="attribution"><span class="source">Tom Womack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>New Zealand may be relatively small, but its fossil record reveals a globally important ecological relationship between the number of species, their role in the ecosystem and ocean temperatures. </p>
<p>We used New Zealand’s exemplary fossil record of molluscs from the past 40 million years to examine how ocean temperatures influence the number of species. Our <a href="https://science.sciencemag.org/content/373/6558/1027">research</a> shows a new, fundamental pattern. </p>
<p>We found an increase in species richness during periods with warmer ocean temperatures, as well as higher numbers of species filling similar ecological roles in New Zealand’s coastal cool-water ecosystems. The latter is a measure known as functional redundancy.</p>
<p>Such ecological redundancy can increase ecosystem resilience to environmental change. Taken at face value, our findings might be seen as encouraging news for New Zealand’s biodiversity in the face of global heating. </p>
<p>But our findings are based on natural changes in ocean temperature in the past. At the rate of current human-driven warming, the unfolding biodiversity crisis — hailed as the <a href="https://advances.sciencemag.org/content/1/5/e1400253.short">sixth mass extinction</a> — is likely to play out differently from previous mass extinction events. </p>
<p>The impact on New Zealand’s future biodiversity is also likely to deviate from the patterns we can glean from the fossil record. </p>
<figure class="align-center ">
<img alt="A layer of fossil molluscs along the banks of the Rangitikei River in a New Zealand fieldsite" src="https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418174/original/file-20210827-6524-d93ioc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">During past periods with warmer ocean temperatures, the number of marine species was likely higher.</span>
<span class="attribution"><span class="source">James Crampton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Measuring biodiversity</h2>
<p>Biodiversity measures the variety of life on Earth, typically as the number or abundance of species. Past patterns of diversity can be used as a baseline for understanding how current human-induced changes are affecting it. </p>
<p>But biodiversity has many dimensions, and a simple count of the number of species only measures one aspect. </p>
<p>Recent <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.3184">research</a> has highlighted the importance of ecosystem function, which describes the range of things organisms do in an ecosystem. Ecosystem function can be measured as functional richness. </p>
<p>For example, the common shellfish toheroa (<em>Paphies ventricosa</em>) and tuatua (<em>Paphies subtriangulata</em>) found along New Zealand’s shorelines are two different bivalve species. But both perform very similar ecological roles. They live on sandy beaches and filter microscopic food particles from the surf. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ocean-ecosystems-take-two-million-years-to-recover-after-mass-extinction-new-research-124328">Ocean ecosystems take two million years to recover after mass extinction – new research</a>
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</em>
</p>
<hr>
<p>We refer to an increase in the number of species performing the same ecological role as high functional redundancy. This has been associated with better ecosystem resilience in the face of environmental change. </p>
<p>Conversely, the loss of species in an ecosystem with low functional redundancy is likely to lead to functional extinction, and as a result, ecosystem collapse. </p>
<figure class="align-center ">
<img alt="Examples of marine fossils held in New Zealand's fossil collection." src="https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=367&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=367&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418175/original/file-20210827-17822-1tmj8uf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=367&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our study is based on thousands of fossil collections from around New Zealand, similar to one shown here.</span>
<span class="attribution"><span class="source">Tom Womack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The results of our study are based on the geographic distribution of fossil species and the relationship to functional richness through geological time. This relationship implies that an increase in ocean temperature around New Zealand should lead to an increase in both the number of species living in our waters and functional redundancy. </p>
<p>This in turn suggests that during past warmer intervals, New Zealand’s ecosystems may have been more resilient to environmental change. </p>
<p>New Zealand’s fossil record of molluscs provides a baseline for what should be expected over hundreds of thousands to millions of years from natural ocean warming. </p>
<p>The observed link between functional redundancy and ocean temperature over the last 40 million years is consistent with observations from the modern, living marine fauna. The latter also shows increasing numbers of species and functional redundancy at warmer, lower latitudes. This suggests this pattern is a long-lived relationship of regional and global importance.</p>
<h2>The future of New Zealand’s shallow marine ecosystems</h2>
<p>The sixth mass extinction refers to the ongoing loss of global biodiversity as a direct cause of human activity. </p>
<p>As atmospheric carbon dioxide levels continue to rise in tandem with increased rates of habitat degradation, we commit currently surviving species to extinction far into the future. This is known as “extinction debt”. </p>
<p>But biodiversity is not evenly distributed across the Earth and individual regions may respond differently to environmental changes. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-sea-creatures-spent-years-crossing-the-ocean-on-rafts-weve-worked-out-how-it-was-possible-143580">Ancient sea creatures spent years crossing the ocean on rafts – we've worked out how it was possible</a>
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<hr>
<p>What does this mean for the conservation of New Zealand’s biodiversity? </p>
<p>Although species richness is expected to increase from the isolated effect of climate warming in New Zealand over long timescales, an ecosystem can simultaneously gain species through species migration while losing native species through extinction. </p>
<p>Recent <a href="https://science.sciencemag.org/content/353/6305/1284.abstract">research</a> also suggests that the unfolding sixth mass extinction is associated with the selective removal of functional groups, for example large predatory fish. This will likely lead to increased rates of functional extinction. </p>
<p>Studies of the <a href="https://www.pnas.org/content/115/4/732">global marine fossil record</a> suggest relatively minimal losses of functional richness during even the largest extinction events in Earth’s history. </p>
<figure class="align-center ">
<img alt="Fossilised scallops from the Chatham Islands, New Zealand" src="https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418176/original/file-20210827-18-g2vv3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fossilised scallops from the Chatham Islands, New Zealand.</span>
<span class="attribution"><span class="source">Tom Womack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This is corroborated in New Zealand’s shallow marine fossil record, where large drops in species richness over the last 40 million years have resulted in minimal loss of functional richness. As a result, the sixth mass extinction could be different and have unforeseeable consequences. </p>
<p>For these reasons, New Zealand’s conservation needs to consider the long-term impact of climate change and focus not only on protecting native species but on preserving ecosystem function.</p>
<p>As we commit to further ocean warming and biodiversity loss, we increase the extinction debt of the future, both globally and regionally. There is growing evidence the impact of human activity, including global heating, will deviate from patterns predicted from natural environmental change in the past.</p>
<p>This is particularly important for temperate marine ecosystems. They are vulnerable to climate change, but cover a large proportion of the Earth’s marine realm. In New Zealand, these ecosystems are home to many endemic animals and plants — our taonga to protect.</p><img src="https://counter.theconversation.com/content/166660/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom Womack does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New Zealand’s conservation needs to consider the long-term impact of climate change and focus not only on protecting native species but on preserving ecological richness.Tom Womack, PhD Candidate, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643212021-07-26T23:11:12Z2021-07-26T23:11:12ZAncient brains: a look inside the extraordinary preservation of a 310-million-year-old nervous system<figure><img src="https://images.theconversation.com/files/411151/original/file-20210714-27-12vxplu.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3012%2C927&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Javier Ortega-Hernández</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Charles Darwin famously discussed the “imperfections” of the geological record in his book On The Origin of Species. He correctly pointed out that unless conditions are just right, it’s unlikely for organisms to be preserved as fossils, even those with bones and shells.</p>
<p>He also said “no organism wholly soft can be preserved”.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/guide-to-the-classics-darwins-on-the-origin-of-species-96533">Guide to the classics: Darwin's On the Origin of Species</a>
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<p>However, after more than a century of fossil hunting since his book was published, we now know the preservation of soft creatures is indeed possible — including some of the most fragile animals, such as <a href="https://www.nationalgeographic.com/science/article/treasure-trove-of-spectacular-fossils-found-in-china">jellyfish</a>.</p>
<p>But what about the really delicate anatomy of animals, such as their internal organs? Can they be fossilised too?</p>
<p>Our study, published today in <a href="https://doi.org/10.1130/G49193.1">Geology</a>, shows how even the intricate brains of ancient aquatic <a href="https://australian.museum/learn/animals/what-are-arthropods/">arthropods</a> (invertebrates with jointed legs) can be preserved in remarkable detail.</p>
<p>The discovery of a 310 million-year-old <a href="https://theconversation.com/living-fossils-we-mapped-half-a-billion-years-of-horseshoe-crabs-to-save-them-from-blood-harvests-141042">horseshoe crab</a> in the US, complete with its brain intact, adds to a recent string of fossil finds which have unearthed some of the oldest arthropods with a preserved <a href="https://www.britannica.com/animal/arthropod/Nervous-system-and-organs-of-sensation">central nervous system</a>.</p>
<p>The horseshoe crab fossil we document in our study sheds new light on how these fragile organs — typically prone to very rapid decay — can be preserved with such fidelity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411027/original/file-20210713-19-deprud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">(A) Specimen of the fossil horseshoe crab <em>Euproops danae</em> from Mazon Creek, Illinois, USA, preserved with its brain intact. (B) Close-up of brain, as indicated by box in image (A). (C) Reconstruction of <em>Euproops danae</em>, including the position and anatomy of the brain.</span>
<span class="attribution"><span class="source">Russell Bicknell</span></span>
</figcaption>
</figure>
<h2>Brain freeze: how to fossilise an arthropod brain</h2>
<p>Most of our knowledge of prehistoric arthropod brains has been sourced from two key types of fossil deposit: amber and those of Burgess Shale-type.</p>
<p><a href="https://www.britannica.com/science/amber">Amber</a> is fossilised resin that oozes through tree bark and is known to trap a variety of organisms. The <a href="https://cosmosmagazine.com/biology/the-history-of-life-in-golden-stones/">entombed individuals</a> are commonly represented by arthropods such as insects — made famous in the original <a href="https://www.youtube.com/watch?v=iMsJe3TymqY">Jurassic Park</a> movie. </p>
<p>These fossils preserve an incredible amount of anatomical detail, as well as <a href="https://eartharchives.org/articles/trapped-in-time-the-top-10-amber-fossils/index.html">behaviours</a>, mainly because very little decay takes place after the organism is rapidly trapped in the resin. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411016/original/file-20210713-15-18ydfzd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A centipede and a neighbouring ant suspended in roughly 23 million-year-old Mexican amber.</span>
<span class="attribution"><span class="source">Greg Edgecombe</span></span>
</figcaption>
</figure>
<p>Using sophisticated imaging technology on these amber fossils, palaeontologists can study tiny arthropod brains <a href="https://link.springer.com/article/10.1007/s00114-010-0703-x">in 3D at minuscule scales</a>. However, the <a href="https://www.amnh.org/explore/news-blogs/research-posts/scientists-find-oldest-amber-arthropods-on-record">oldest arthropods in amber</a> only extend back to the Triassic Period (around 230 million years ago).</p>
<p><a href="https://burgess-shale.rom.on.ca/en/science/origin/04-cambrian-explosion.php#fossil-3">Burgess Shale-type deposits</a> are much older, being Cambrian in age (typically 500 to 520 million years old). They contain an abundance of exceptionally preserved marine arthropods. </p>
<p>These fossils are very important as they represent what are unmistakably some of the oldest animals, and can therefore inform us on their origins and earliest evolutionary history. Their remains are primarily preserved as carbon films in mudstone. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=822&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=822&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=822&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1034&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1034&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411138/original/file-20210714-17-i0gsgl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1034&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Cambrian arthropod <em>Chengjiangocaris kunmingensis</em> from China. See the bead-like ventral nerve cord preserved in the fossil (A) and its central position in the reconstruction (B).</span>
<span class="attribution"><span class="source">Javier Ortega-Hernández</span></span>
</figcaption>
</figure>
<p>The fossilisation process starts with storm-induced mudflows that sweep up the delicate animals and bury them in the seafloor in low oxygen conditions. Over time, the mud turns to stone and is compressed, leaving the animals pancaked in the rocks. </p>
<p>Many Burgess Shale-type arthropod specimens preserve internal organs, especially the gut. But fewer show parts of the central nervous system, such as the optic nerves, ventral nerve cord or the brain.</p>
<h2>Mind-boggling preservation</h2>
<p>Our new fossil demonstrates arthropod brains can be preserved in an entirely different way. The specimen of the horseshoe crab, <em>Euproops danae</em>, comes from the world-famous <a href="https://pubs.geoscienceworld.org/jgs/article/176/1/1/545488/The-Mazon-Creek-Lagerstatte-a-diverse-late">Mazon Creek deposit</a> of Illinois, in the US. Fossils from this deposit are preserved within concretions made of an iron carbonate mineral called siderite.</p>
<p>Some of the Mazon Creek animals, such as the bizarre <a href="https://theconversation.com/the-mysterious-tully-monster-fossil-just-got-more-mysterious-126531">“Tully Monster”</a>, are entirely soft-bodied. This suggests special conditions must have been in place to preserve them.</p>
<p>We have shown, for the first time, that the Mazon Creek animals were not only moulded by the rapid formation of siderite that entombed their entire bodies, but also that the siderite quickly encased their internal soft tissues before they could decompose. </p>
<p>Notably, the brain of <em>Euproops</em> is replicated by a white-coloured clay mineral called kaolinite. This mineral cast would have formed later within the void left by the brain, long after it had decayed. Without this conspicuous white mineral, we may have never spotted the brain.</p>
<h2>A fossil no-brainer</h2>
<p>One of the challenges of interpreting ancient arthropod anatomy is the lack of close modern relatives available for comparison. But luckily for us, <em>Euproops</em> can be compared to the four species of living horseshoe crabs. </p>
<p>Even to the untrained eye, a comparison of the fossil’s nervous system with that of a modern horseshoe crab (below) leaves little question that the same structures are found in both species, despite them being separated by 310 million years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=199&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=199&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=199&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=250&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=250&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411029/original/file-20210713-27-1xz1pip.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=250&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">(A) The fossil and (B and C) interpretive drawings of the <em>Euproops danae</em> brain, and (D) the brain of a modern juvenile horseshoe crab, <em>Limulus polyphemus</em>.</span>
<span class="attribution"><span class="source">(A-C) Russell Bicknell, (D) Steffen Harzsch</span></span>
</figcaption>
</figure>
<p>The fossil and living nervous systems match up in their arrangements of nerves to the eyes and appendages, and show the same central opening for the oesophagus to pass through. </p>
<p>Uncovering these exceptional specimens gives palaeontologists a rare glimpse into the deep past, enhancing our understanding of the biology and evolution of long-extinct animals. It seems Charles Darwin need not have been so pessimistic about the fossil record after all.</p>
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<strong>
Read more:
<a href="https://theconversation.com/our-500-million-year-old-nervous-system-fossil-shines-a-light-on-animal-evolution-55460">Our 500 million-year-old nervous system fossil shines a light on animal evolution</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164321/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Paterson receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Greg Edgecombe receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Javier Ortega-Hernández receives funding from the National Science Foundation (NSF), and Harvard University. </span></em></p><p class="fine-print"><em><span>Robert Gaines receives funding from the US National Science Foundation, the Gordon and Betty Moore Foundation, and Pomona College.</span></em></p><p class="fine-print"><em><span>Russell Dean Christopher Bicknell receives funding from the Australian Research Council and the University of New England.</span></em></p>Researchers have found a new way by which the brains of ancient animals can be preserved.John Paterson, Professor of Earth Sciences, University of New EnglandGreg Edgecombe, Merit Researcher, Natural History MuseumJavier Ortega-Hernández, Assistant Professor, Harvard Kennedy SchoolRobert Gaines, Professor of Geology, Vice President for Academic Affairs and Dean of the College, Pomona CollegeRussell Dean Christopher Bicknell, Post-doctoral researcher in Palaeobiology, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643062021-07-15T13:43:36Z2021-07-15T13:43:36ZFossil tracks and trunk marks reveal signs of ancient elephants on South Africa’s coast<figure><img src="https://images.theconversation.com/files/410693/original/file-20210711-15-tgjz7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">New fossil evidence reveals more about how African bush elephants' ancient ancestors moved about a South African landscape.</span> <span class="attribution"><span class="source">Gunter Nuyts/Shutterstock</span></span></figcaption></figure><p>Hundreds of thousands of years ago, South Africa’s Cape south coast looked very different. Some of the species that roamed this area are now extinct; others evolved over the millennia and their modern descendants inhabit different areas – some far away, others nearby.</p>
<p>For instance, in the 19th century, a population that came to be known as the “<a href="https://www.knysnamuseums.co.za/pages/the-knysna-elephants/">Knysna elephants</a>” (a reference to the nearest big town) were the most southerly group of elephants in Africa. Over time they became the only free-ranging elephants in South Africa. Their numbers were decimated by the ivory market and habitat transformation. <a href="https://bioone.org/journals/african-journal-of-wildlife-research/volume-49/issue-1/056.049.0016/And-Then-There-was-One--A-Camera-Trap-Survey/10.3957/056.049.0016.short">Evidence</a> indicates that only one elephant, an adult female in her forties, remains. </p>
<p>Now, about 18km from the area that lone elephant occupies, we have found <a href="https://www.doi.org/10.1017/qua.2021.32">new evidence</a> of her ancient ancestors in the form of fossil tracksites from the <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene</a> Epoch. These sites vary in age from 400,000 to 35,000 years. The tracks, preserved in aeolianites (the cemented remains of dune surfaces) and cemented beach deposits, dovetail with <a href="https://doi.org/10.17159/sajs.2019/4805">more recent evidence</a> that elephants historically made widespread use of open areas in the region. </p>
<p>Along with elephant tracks from sites on the Cape south coast, we <a href="https://www.doi.org/10.1017/qua.2021.32">identified</a> what appears to be the first example in the global trace fossil record of elephant trunk-drag impressions. We interpret the impressions in question as having been made by an elephant either dragging its trunk or dragging something it was gripping in its trunk. These marks are consistent with the sort of trunk-drag traces described in tracking manuals and on <a href="https://www.elephantvoices.org/multimedia-resources/gestures-db-structure/413-sexual/advertisement-attraction/1770-trunk-bounce-drag.html?layout=gesture">various websites</a>.</p>
<p>The extant African bush elephant (<em>Loxodonta africana</em>) – the Knysna elephant belongs to this species – is known to show trunk-dragging behaviour under a variety of circumstances, including <a href="https://safarisafricana.com/elephant-musth-facts/">musth</a>, sporadic periods during which bull elephants are particularly aggressive.</p>
<p>Our <a href="https://www.doi.org/10.1017/qua.2021.32">recent article</a> focused on the 35 elephant tracksites, which are among the more than <a href="https://www.livescience.com/40311-pleistocene-epoch.html">300 vertebrate Pleistocene tracksites</a> that we have identified along a 350km stretch of the coastline since 2008. Such fossil tracksites can tell us many things about what happened on those ancient dunes and beaches, and the ancient environment that the elephants roamed.</p>
<p>For one, they offer insights into the <a href="https://doi.org/10.17159/sajs.2019/4805">probable history</a> of the Knysna elephants, suggesting that the remaining elephants retreated into dense afrotemperate forest for protection in recent centuries, where hunters had difficulty finding them. </p>
<p>The tracksites are also important because elephants are ecosystem engineers. Their presence may have large-scale effects on the landscape: for example, they can transform woody habitats to more open habitats. They may well have facilitated the development and maintenance of the mosaic of woodland and grassland habitats that characterised the huge, now-submerged <a href="https://doi.org/10.1016/j.quascirev.2019.105866">Palaeo-Agulhas Plain</a> during the Pleistocene.</p>
<h2>Large tracks</h2>
<figure class="align-center ">
<img alt="A smooth grey rock surface, with some pock marks, alongside the blue ocean. There is a mark in the rock's surface that looks like a deep, diagonal groove." src="https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=479&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=479&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=479&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=602&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=602&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410694/original/file-20210711-15-eps2jj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=602&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This elongated groove was likely caused by an elephant dragging its trunk or dragging something it was carrying in its trunk.</span>
<span class="attribution"><span class="source">Charles Helm</span></span>
</figcaption>
</figure>
<p>Fossil elephant tracks can take a number of forms. Sometimes they are familiar depressions; sometimes they appear as natural casts, representing the layer that filled in the tracks and, so, protruding down from the ceilings of overhangs. They can also be seen in profile in cliff outcrops. </p>
<p>Elephant tracks, predictably given the animals’ size, often deform underlying layers. Sometimes, when these tracks can be discerned in profile in multiple successive layers, <a href="http://wiredspace.wits.ac.za/handle/10539/23736">conclusions</a> can be drawn about repeated use of an area over time. In some cases, elephant tracks on beaches were <a href="https://doi.org/10.2112/JCOASTRES-D-20-00064.1">precursors for the formation of potholes</a>. In places they have been eroded into bizarre shapes, which beach hikers admire and pass by without knowing their intriguing origins.</p>
<p>Analogies can be drawn between Pleistocene elephant tracks and Mesozoic dinosaur tracks: in both scenarios they were the largest tracks of their time, made by the heaviest creatures. In fact, it appears that the elephant tracks we <a href="http://wiredspace.wits.ac.za/handle/10539/28633">described</a> at one site, measuring as much as 70cm in diameter, are the largest tracks ever identified since the “Age of Dinosaurs”.</p>
<p>The elephant trunk-drag site was identified on an aeolianite surface in the <a href="https://www.capenature.co.za/reserves/goukamma-nature-reserve">Goukamma Nature Reserve</a>, around 500km east of Cape Town. There were also tracks of the extinct long-horned buffalo and of smaller buck species, two coprolite sites – that is, fossilised dung – and small carnivore tracks, alongside numerous examples of elephant tracks.</p>
<p>The site is only exposed at low tide, being subject to intense wave action during high tides and storm surges. It is also usually covered by metres-thick layers of beach sand, so we were fortunate to find it during a rare occasion in which it was exposed.</p>
<figure class="align-center ">
<img alt="A shirtless man in blue shorts is seen underwater, a ruler in his hand held against a rock surface. A large indentation is visible on the rock." src="https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410695/original/file-20210711-23-2md2zs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Measuring an underwater elephant track.</span>
<span class="attribution"><span class="source">Charles Helm</span></span>
</figcaption>
</figure>
<p>Here, beside an elephant trackway comprising 13 tracks which traversed a cemented dune slope, we encountered a “serpentine” sequence of two long, slightly curved groove features with an outward convexity, one on each side of the trackway. Displacement rims were present; these indicate that a compressive force had caused the grooves. In one spot we could tell that the grooves were registered first, and then the tracks, consistent with how elephant footprints often are superimposed on parts of trunk-drag impressions. </p>
<p>We considered interpretations other than trunk-drag impressions, but any alternative possibilities appeared to be truly remote.</p>
<h2>Filling in gaps</h2>
<p>There are no body fossils of elephants from this time period, so the available information about how these gigantic animals moved through the ancient landscapes currently depends entirely on the track record. </p>
<p>Each elephant tracksite we identify evokes a sense of wonder at how the tracks – and in this case, the trunk-drag impression – survived, against the odds, and are now amenable to our interpretation, as we try to read the story the rocks tell us.</p><img src="https://counter.theconversation.com/content/164306/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Helm does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There are no body fossils of elephants from this time period, so the available information of how these gigantic animals moved through the ancient landscapes depends entirely on the track record.Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1633092021-06-28T09:37:41Z2021-06-28T09:37:41ZPrehistoric creatures flocked to different latitudes to survive climate change – the same is taking place today<figure><img src="https://images.theconversation.com/files/408173/original/file-20210624-23-167gtr3.png?ixlib=rb-1.1.0&rect=739%2C8%2C1932%2C809&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Dinosaur_park_formation_fauna.png">J.T. Csotonyi/wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Life on Earth is most diverse at the equator. This pattern, where species biodiversity increases as we move through the tropics towards the equator, is seen on land and in the oceans, and has been documented across a broad range of animal and plant groups, from <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001775">mammals</a> and <a href="https://www.journals.uchicago.edu/doi/abs/10.1086/519009?casa_token=KISLkv8QEj4AAAAA%3A6-lZhiu31_ooIxOAJNYQZzW-bGT8sF2extvVAtV0abeqi_0-OduN1OU7S_dK6UwghhYgzh6Ux14&journalCode=an">birds</a>, to <a href="https://www.nature.com/articles/s41467-018-04218-4">ants</a> and even <a href="https://www.journals.uchicago.edu/doi/full/10.1086/508635?casa_token=LSurevVXHl4AAAAA%3Aact0lSJMtF8MzBbm1GiJQs2lA6uS1vAWadix6qVxgJ7eJe0ROIKekeHwd_5IvRYLxM6iBpjyQGM">trees</a>.</p>
<p>Despite this pattern being so striking today, the distribution of biodiversity across latitudes – called the <a href="https://www.sciencedirect.com/science/article/pii/B9780128096659098098">latitudinal biodiversity gradient</a> – hasn’t always been like this. Studies looking at the evolution of biodiversity by latitude have shown that during some intervals in Earth’s history, species biodiversity was actually highest at latitudes far from the equator.</p>
<p>Understanding why latitudinal biodiversity has shifted over hundreds of millions of years, often linked to <a href="https://theconversation.com/five-mass-extinctions-and-what-we-can-learn-from-them-about-the-planet-today-79971">mass extinction events</a>, is critical in today’s world, where we’re facing climate change, habitat loss and decreasing biodiversity worldwide. Looking back in geological time reveals an alarming picture of what we’re set to lose if we fail to address increasing global temperatures.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-mass-extinction-and-are-we-in-one-now-122535">What is a 'mass extinction' and are we in one now?</a>
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<p><a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.ecolsys.34.012103.144032?casa_token=AnfHQJDzSNQAAAAA:-m18WiYPzX5IRGE8mTLJVbgP-Hg00Tp0AzU_0mgAbZRjsDqNjgaTjmqXxksJZGFIuqplNbFKTo99">Several different hypotheses</a> have been proposed to explain why high biodiversity clusters around certain latitudes, but climate is often regarded as a key driver, both in the present day and through history as shown by the <a href="https://www.sciencedirect.com/science/article/pii/S0169534713002358">geological record</a>. Climate affects organisms in many ways, including <a href="https://www.jstor.org/stable/2401068?casa_token=kqQ9fnw-n5EAAAAA%3AtpczwQNR_ceMjjm8cRuEWkSHaUic__OhypraifJQ1HZ4jMUe1VRoz3-LJEH1btrdlqV18Q4T9u2g0GeLo2A7d47Gop-gPNF7QHgcT3LXbYoa0fStRhs&seq=1#metadata_info_tab_contents">where they can live</a>, when they <a href="https://www.journals.uchicago.edu/doi/abs/10.1086/285538">reproduce</a>, and even how they control their internal processes such as <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.2307/1940107">temperature regulation</a>.</p>
<p>Modern biodiversity peaks in low-latitude equatorial regions, such as in the tropical rainforests of the Amazon and central Africa. This pattern is more likely to be recorded during “icehouse” times, when ice sheets are present in both poles simultaneously – like today. </p>
<p>During warmer intervals, called “<a href="https://theconversation.com/hothouse-earth-our-planet-has-been-here-before-heres-what-it-looked-like-101413">hothouse</a>” or “greenhouse” Earth states, bimodal peaks have been recorded. This means there were two bands where biodiversity was highest, and these wrapped around the Earth at mid-latitudes, or regions sitting between 25° and 65° north and south of the equator.</p>
<figure class="align-center ">
<img alt="Map of earth showing latitudes" src="https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=443&fit=crop&dpr=1 754w, https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=443&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/408151/original/file-20210624-15-14qetub.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=443&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Biodiversity was once highest around today’s Mediterranean and southern Africa.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/world-map-latitude-degrees-north-pole-1962211288">chemistrygod/Shutterstock</a></span>
</figcaption>
</figure>
<p>The fossil record provides our best window into Earth’s ancient biodiversity. But estimating patterns of biodiversity from the fossil record has been tricky, because it’s riddled with <a href="https://www.theguardian.com/science/lost-worlds/2012/aug/17/bias-fossil-record">gaps and biases</a> that limit our understanding. </p>
<p>But in the past two decades, <a href="https://www.palaeontologyonline.com/articles/2018/patterns-in-palaeontology-how-do-we-measure-biodiversity-in-the-past/">new analytical techniques</a> have allowed palaeontologists to estimate what prehistoric biodiversity patterns might have looked like, even from data that might appear, superficially at least, a little patchy. These techniques have recently revealed what latitudinal diversity looked like over 200 million years ago, in the aftermath of the most devastating mass extinction events ever recorded.</p>
<h2>Prehistoric habitats</h2>
<p>The <a href="https://www.nationalgeographic.com/science/article/permian-extinction">end-Permian mass extinction</a>, which took place 251 million years ago, resulted in the extinction of <a href="https://www.sciencedirect.com/science/article/pii/S0031018212007018?casa_token=niK9Iax0BI8AAAAA:QQariz_exhQIO4g21fQmdcdep3zm85Cp0bRF20uqZ_A9D1tKoB0MKfEa6Z5Gsosbo13EzALS">over 80% of species</a> on Earth. The extinction event was caused by an <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252959/">unstable climate</a> after widespread volcanic eruptions. At this time, and for the following 50 million years of the <a href="https://www.nhm.ac.uk/discover/the-triassic-period-the-rise-of-the-dinosaurs.html">Triassic period</a>, the continents were arranged into a single landmass, known as <a href="https://www.britannica.com/place/Pangea">Pangaea</a>.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0031018211002987?casa_token=ZZAy60g_G0wAAAAA:qsksnxx-aqK99FvKPOLT9D2j2DOonMAOojDEXjK6a_wcR67O4i1FFfQ-kwB93vazp9MqaegG">The climate</a> of the period was generally hotter and more arid than the present day, and vast deserts surrounded the equator. Instead of ice sheets, polar regions had temperate climates, like those we find at mid-latitudes today. Life in the oceans, meanwhile, was not only subjected to equatorial sea surface temperatures <a href="https://science.sciencemag.org/content/338/6105/366.abstract?casa_token=WkTNFatVVJ0AAAAA:RSix9UmDSmWYColl3dasvxhMxIXxk5J9DSferDd2RpyVw8auWM6Fay3cQRYdhzsX99Ycfg2OKe4wPg">as high as 40°C</a>, but also falling oxygen levels and ocean acidification.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/global-warmings-evil-twin-ocean-acidification-19017">Global warming’s evil twin: ocean acidification</a>
</strong>
</em>
</p>
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<p>The period following the end-Permian mass extinction was one of recovery. A <a href="https://www.pnas.org/content/117/30/17578">recent study</a> found a latitudinal diversity gradient in the oceans similar to today’s was present for much of the Triassic (251–201 million years ago). Immediately following the mass extinction event, however, the researchers found a flat biodiversity gradient. There was no peak in species biodiversity at any latitude, which they attributed to high extinction rates near the equator due to extreme warming and ocean anoxia – when oxygen in ocean water is depleted.</p>
<p>On land, the vertebrates that survived the mass extinction soon developed a <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2020.1125">bimodal</a> latitudinal biodiversity gradient, with the highest peak occurring in low-latitude regions of the northern hemisphere, but with a second peak in mid-latitude regions of the southern hemisphere. This pattern is likely to have been driven by the extreme climatic conditions on Pangaea, including high temperatures and strongly seasonal rainfall, associated with the formation of a “<a href="https://www.journals.uchicago.edu/doi/abs/10.1086/648217">megamonsoon</a>”.</p>
<p>Later in the <a href="https://theconversation.com/triassic-mass-extinction-may-give-clues-on-how-oceans-will-be-affected-by-climate-change-39655">Triassic</a>, on the approach to yet another <a href="https://www.britannica.com/science/end-Triassic-extinction">mass extinction event</a>, most land vertebrates, including early mammals and early dinosaurs, exhibited <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12514">high diversity</a> at mid-latitudes, both north and south of the equator. This pattern is similar to that recorded for land vertebrates <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2017.0231">during the Permian period</a>, just before the mass extinction. </p>
<p>One exception were the <a href="https://www.britannica.com/animal/crurotarsan-reptile">pseudosuchians</a> – the group that consists of <a href="https://www.nature.com/articles/ncomms9438/">crocodilians</a> and their fossil relatives. Interestingly, while the latitudinal biodiversity of other species shifted over the subsequent 200 million years, arriving at the equator in the present day, pseudosuchian biodiversity has remained highest at low latitudes throughout their <a href="https://www.nature.com/articles/ncomms9438">entire evolutionary history</a>. </p>
<p>This is likely due to their physiology, specifically their tolerance of high temperatures. Reptiles are <a href="https://www.thoughtco.com/ectothermic-definition-2291709">ectotherms</a>, or “cold-blooded” organisms, that rely on their external environment to regulate their internal body temperature. Today, crocodiles and other reptiles are restricted to areas of the world with warmer, more stable temperatures, and the same would have been true of their fossil relatives.</p>
<h2>Prehistory repeats?</h2>
<p>These insights into past mass extinction events are critical for understanding how Earth’s current patchwork of biodiverse regions could change. As global temperatures <a href="https://timescavengers.blog/climate-change/co2-past-present-future/">continue to rise</a>, some studies have predicted that species will disperse towards the poles from equatorial regions – but if the pace of change is too rapid, they <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2014.1995">risk going extinct</a>. </p>
<p>Others suggest that global warming might lead to the climate becoming more similar across different latitudes, potentially producing a peak in biodiversity at mid-latitudes. There’s already evidence that marine latitudinal biodiversity has become <a href="https://www.pnas.org/content/118/15/e2015094118.short?casa_token=FCeWYmuriVQAAAAA:dKaWWdlx60uK189AdfRdgeLQafwlAZzvsuhm8bzLQpj6nvoJpKAzH8N38rxwLRvtxlV_g0xqLTT9Fw">increasingly bimodal</a> over the last 50 years. </p>
<p>With a possible “<a href="https://www.nhm.ac.uk/discover/what-is-mass-extinction-and-are-we-facing-a-sixth-one.html">sixth mass extinction</a>” looming, or even already <a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">taking hold</a>, a <a href="https://science.sciencemag.org/content/355/6325/eaah4787">long-term perspective</a> will be critical for understanding how to sustain Earth’s biodiversity into the future.</p><img src="https://counter.theconversation.com/content/163309/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Dunne receives funding from The Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Bethany Allen has received funding from the UK Natural Environment Research Council (NERC).</span></em></p>Today, Earth’s biodiversity is highest at the equator – but it hasn’t always been this way.Emma Dunne, Postdoctoral Researcher, School of Geography, Earth and Environmental Sciences, University of BirminghamBethany Allen, PhD Student, School of Earth and Environment, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1445742020-08-17T20:13:40Z2020-08-17T20:13:40ZIn a land of ancient giants, these small oddball seals once called Australia home<figure><img src="https://images.theconversation.com/files/353100/original/file-20200817-16-1blpziv.jpg?ixlib=rb-1.1.0&rect=55%2C31%2C5187%2C3293&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Artwork by Peter Trusler</span>, <span class="license">Author provided</span></span></figcaption></figure><p>When most of us think of the prehistoric past, we envision a world of bizarre, often fearsome giants. From dinosaurs to mammoths and even <a href="https://theconversation.com/happy-6ft-ancient-penguins-were-as-tall-as-people-weve-discovered-the-species-that-started-the-downsizing-trend-128546">penguins</a>, life then seemed larger than life today. </p>
<p>Millions of years ago in Australia, giant goannas, kangaroos and <a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">diprotodontids</a> (wombat relatives) roamed the landscape. The seas teemed with gargantuan predators such as the infamous “megalodon” shark and so-called giant killer sperm whales.</p>
<p>Fossils from this lost world can be found in sandstone rocks, between five million and six million years old, at Beaumaris – a bayside suburb in Melbourne and one of Australia’s most significant urban fossil sites. Here, fossils of ancient marine animals often wash ashore, eroded out of rocks by the tides.</p>
<p>However, some of these fossils are now revealing “jumbo” was not the only size for extinct animals. Our team’s research, published today in the <a href="https://doi.org/10.1093/zoolinnean/zlaa075">Zoological Journal of the Linnean Society</a>, reports nine new seal fossils from Beaumaris, which we suspect came from nine different individuals.</p>
<p>The findings paint a picture of a relatively small animal, making its way through a world of giants.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-giant-wombat-relative-that-scratched-out-a-living-in-australia-25-million-years-ago-141296">Meet the giant wombat relative that scratched out a living in Australia 25 million years ago</a>
</strong>
</em>
</p>
<hr>
<h2>More than doubling the seal fossil record</h2>
<p>Melburnians have been collecting fossils from Beaumaris for more than 100 years. Yet it continues to produce remarkable and scientifically important finds.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A beach foreshore in Melbourne." src="https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353105/original/file-20200817-16-1py6m09.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The fossils we studied were found on the foreshore of Beaumaris, Melbourne.</span>
<span class="attribution"><span class="source">Erich Fitzgerald</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This includes extremely rare fossils of animals such as seals. Previously, scientists had studied only one seal fossil from this site. </p>
<p>The nine new fossils detailed in our research were collected and donated to Museums Victoria by local scientists and citizen scientists over the past 88 years. They have more than doubled the known fossil record of seals in Australia.</p>
<p>These fossils represent the oldest evidence of seals in Australia and were identified as “true seals”, a group mostly known from the Arctic and Antarctic. True seals belong to a different group to Australia’s fur seals and sea lions (eared seals), which only arrived in the region <a href="https://lens.monash.edu/@science/2020/04/04/1379872/rare-fossil-tooth-discovery-reveals-extinct-group-of-seals">about 500,000 years ago</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Seal fossil specimens" src="https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353108/original/file-20200817-14-1ano6fp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In total, we found nine seal fossil specimens from Beaumaris, from potentially nine different individuals.</span>
<span class="attribution"><span class="source">Erich Fitzgerald and James Rule</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In particular, one of the fossils we identified is a monachine (a southern true seal). Today, these are represented by animals such as leopard or elephant seals in the Southern Ocean surrounding the Antarctic, to which they are related.</p>
<p>Size estimates found the Beaumaris monachines to have been quite small, at only 1.7 metres long. This is similar to the size of today’s Northern Hemisphere seals such as the harbour seal. </p>
<p>However, the Beaumaris seal’s living relatives are much larger – usually 3m long or more. Modern leopard seals can grow to more than 3m long, while elephant seals can reach up to a gigantic 5m in length. </p>
<p>Most fossil whales found at Beaumaris are also smaller than their living counterparts. </p>
<p>This is the opposite trend to many other animal groups with fossils found there, including some sharks and <a href="https://www.australiangeographic.com.au/news/2012/06/giant-bony-toothed-bird-fossil-found/">seabirds</a>, wherein the extinct animals were much larger than those alive today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353111/original/file-20200817-22-1h4hmrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The extinct Beaumaris seal was much smaller than its living relatives today.</span>
<span class="attribution"><span class="source">Art by Peter Trusler</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>An uncertain future for marine life</h2>
<p>Why is finding small seals at Beaumaris important? </p>
<p>Five million years ago, before the ice ages, the average annual temperature in southeast Australia was about 2–4°C warmer than it is today, with sea levels up to 25m higher.</p>
<p>These warmer oceans supported a greater diversity of marine megafauna than today, with longer but less energy-efficient food chains. These chains only had room for a few large top predators, such as megalodon sharks. And this may have limited the size of other top predators, including seals. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=310&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=310&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=310&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=390&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=390&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353109/original/file-20200817-20-n6dfg6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=390&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This chart shows the history of seals’ size evolution in Australia, compared to large sharks.</span>
<span class="attribution"><span class="source">Peter Trusler and James Rule</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This is important. It suggests the large size of Antarctic seals living in the Southern Ocean today is due to colder oceans with more energy-efficient food chains, in which more food is available for marine animals. </p>
<p>If climate change continues to warm the oceans, food chains may once again start to become less energy efficient, resulting in a loss of the resources today’s large seals rely on for survival.</p>
<p>The discovery of seal fossils at Beaumaris has implications for not only unlocking the past, but also for contextualising the future. </p>
<p>It shows the biodiversity and ecology of marine megafauna off southern Australia originated during the long-term transition from a warmer to colder world – a process that only recently began changing trajectory.</p>
<p>To this day, the fossil site at Beaumaris continues to reveal scientifically important finds, thanks to members of the public working with scientists from Museums Victoria.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-meg-the-oceans-fossil-record-is-a-treasure-trove-for-potential-monster-movies-101202">The Meg: the ocean's fossil record is a treasure trove for potential monster movies</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/144574/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Patrick Rule receives funding from an Australian Government Research Training Program Scholarship, and the Robert Blackwood Scholarship. </span></em></p><p class="fine-print"><em><span>Erich Fitzgerald, via Museums Victoria, receives funding for research on Beaumaris fossils from philanthropic and community donations.</span></em></p><p class="fine-print"><em><span>Justin W. Adams does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our new research has more than doubled the known fossil record of seals in Australia.James Patrick Rule, Palaeontology PhD Candidate, Monash UniversityErich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria Research InstituteJustin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1436202020-08-12T20:13:03Z2020-08-12T20:13:03ZFrom cave art to climate chaos: how a new carbon dating timeline is changing our view of history<figure><img src="https://images.theconversation.com/files/352428/original/file-20200812-23-cpm0hy.jpg?ixlib=rb-1.1.0&rect=150%2C110%2C6559%2C4355&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Geological and archaeological records offer important insights into what seems to be an increasingly uncertain future. </p>
<p>The better we understand what conditions Earth has already experienced, the better we can predict (and potentially prevent) future threats. </p>
<p>But to do this effectively, we need an accurate way to date what happened in the past. </p>
<p>Our research, published today in the journal <a href="https://www.cambridge.org/core/journals/radiocarbon/calibrations/intcal-20">Radiocarbon</a>, offers a way to do just that, through an updated method of calibrating the <a href="https://c14.arch.ox.ac.uk/dating.html">radiocarbon timescale</a>.</p>
<h2>An amazing tool for perusing the past</h2>
<p>Radiocarbon dating has revolutionised our understanding of the past. It is nearly 80 years since Nobel Prize-winning US chemist Willard Libby <a href="https://www.nature.com/articles/d41586-019-01895-z">first suggested</a> minute amounts of a radioactive form of carbon are created in the upper atmosphere. </p>
<p>Libby correctly argued this newly formed radiocarbon (or C-14) rapidly converts to carbon dioxide, is taken up by plants during photosynthesis, and from there travels up through the food chain. </p>
<p>When organisms interact with their environment while alive, they have the same proportion of C-14 as their environment. Once they die they stop taking in new carbon.</p>
<p>Their level of C-14 then halves every 5,730 years due to <a href="https://www.esrl.noaa.gov/gmd/ccgg/isotopes/decay.html">radioactive decay</a>. An organism that died yesterday will still have a high level of C-14, whereas one that died <a href="https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/radiocarbon-dating.html">tens of thousands of years ago will not</a>. </p>
<p>By measuring the level of C-14 in a specimen, we can deduce how long ago that organism died. Currently, with <a href="https://www.nature.com/articles/d41586-019-01895-z">this method</a>, we can date remains up to 60,000 years old.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-radiocarbon-dating-and-how-does-it-work-9690">Explainer: what is radiocarbon dating and how does it work?</a>
</strong>
</em>
</p>
<hr>
<h2>A seven-year effort</h2>
<p>If the level of C-14 in the atmosphere had always been constant, radiocarbon dating would be straightforward. But it hasn’t.</p>
<p>Changes in the <a href="https://wserv4.esc.cam.ac.uk/pastclimate/?page_id=19">carbon cycle</a>, impinging <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/cosmic-radiation">cosmic radiation</a>, the <a href="https://www.pnas.org/content/112/31/9542">use of fossil fuels</a> and <a href="https://theconversation.com/anthropocene-began-in-1965-according-to-signs-left-in-the-worlds-loneliest-tree-91993">20th century nuclear testing</a> have all caused large variations over time. Thus, all radiocarbon dates need to be adjusted (or calibrated) to be turned into accurate calendar ages.</p>
<p>Without this adjustment, dates could be out by up to 10-15%. <a href="https://www.cambridge.org/core/journals/radiocarbon/calibrations">This week we report</a> a seven-year international effort to recalculate three radiocarbon calibration curves: </p>
<ul>
<li>IntCal20 (“20” to signify this year) for objects from the northern hemisphere</li>
<li>SHCal20 for samples from the ocean-dominated southern hemisphere</li>
<li>Marine20 for samples from the world’s oceans.</li>
</ul>
<figure class="align-right ">
<img alt="Close-up of bristlecone pine tree rings." src="https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352243/original/file-20200811-20-1ciaghc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We dated bristlecone pine tree rings from the second millennium BC.</span>
<span class="attribution"><span class="source">P. Brewer/Uni of Arizona</span></span>
</figcaption>
</figure>
<p>We constructed these updated curves by measuring a plethora of materials that record past radiocarbon levels, but which can also be dated by other methods. </p>
<p>Included in the archives are tree rings from ancient logs preserved in wetlands, cave stalagmites, corals from the continental shelf and sediments drilled from lake and ocean beds. </p>
<figure class="align-center ">
<img alt="An ancient New Zealand kauri tree log." src="https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/351532/original/file-20200806-24-1vpdpwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ancient New Zealand kauri (<em>Agathis australis</em>) logs like this example were used to help construct the calibration curves. This tree is about 40,000 years old and was found buried underground.</span>
<span class="attribution"><span class="source">Nelson Parker</span></span>
</figcaption>
</figure>
<p>In total, the new curves are based on almost 15,000 radiocarbon measurements taken from objects up to 60,000 years old.</p>
<p>Advances in radiocarbon measurement using <a href="https://en.wikipedia.org/wiki/Accelerator_mass_spectrometry">accelerator mass spectrometry</a> mean the updated curves can use very small samples, such as single tree rings from just one year’s growth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of an ancient stalagmite." src="https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=177&fit=crop&dpr=1 600w, https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=177&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=177&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=223&fit=crop&dpr=1 754w, https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=223&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/352423/original/file-20200812-20-685xzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=223&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stalagmites from inside the Hulu Cave in China were key to estimating the amount of radiocarbon present in objects between 14,000 and 55,000 years old.</span>
<span class="attribution"><span class="source">Hai Cheng</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Reassessing old beliefs</h2>
<p>The new radiocarbon calibration curves provide previously impossible precision and detail. As a result, they greatly improve our understanding of how Earth has evolved and how these changes impacted its inhabitants.</p>
<p>One example is the rate of environmental change at the end of the most recent ice age. As the world started to warm some 18,000 years ago, vast ice sheets covering Antarctica, North America (including Greenland) and Europe melted – returning huge volumes of fresh water to the oceans.</p>
<p>But the sea level didn’t rise at a consistent rate like the global temperature. Sometimes it was gradual and other times extremely rapid.</p>
<p>A prime location to detect past sea levels is the <a href="https://www.britannica.com/place/Sunda-Shelf">Sunda Shelf</a>, a large platform of land that was once part of continental Southeast Asia.</p>
<p><a href="https://science.sciencemag.org/content/288/5468/1033.full">One study</a> published in 2000 showed mangrove plant remains found on the seabed recorded a catastrophic 16-metre sea level rise over several hundred years (about half a metre each decade). This event, known as <a href="https://www.giss.nasa.gov/research/briefs/gornitz_10/">Meltwater Pulse-1A</a>, flooded the Sunda Shelf. </p>
<p>Our latest work has modified this story considerably. The new calibration curves reveal this extreme phase of sea level rise actually began 14,640 years ago and lasted just 160 years. </p>
<p>This equates to a staggering one-metre rise each decade – a sobering lesson for the future, considering the current much lower <a href="https://www.theguardian.com/environment/2020/may/08/sea-levels-could-rise-more-than-a-metre-by-2100-experts-say">projected changes for the end of this century</a>. </p>
<h2>An extra half a millennium of art</h2>
<p>Going further back in time, we also looked at some of the world’s oldest cave art in France’s <a href="https://archeologie.culture.fr/chauvet/en">Chauvet Cave</a>, first discovered in 1994. </p>
<p>This cave contains hundreds of beautifully preserved paintings. They depict a European menagerie with long-extinct mammoths, cave lions and woolly rhinoceroses, captured in real-life scenes that provide a window into a lost world.</p>
<p>The Chauvet Cave reveals the artistic sophistication of our <a href="http://www.bradshawfoundation.com/chauvet/index.php">early ancestors</a> in phenomenal detail.</p>
<figure class="align-center ">
<img alt="Chauvet cave paintings depicting wild animals including horses." src="https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=595&fit=crop&dpr=1 600w, https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=595&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=595&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=747&fit=crop&dpr=1 754w, https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=747&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/351623/original/file-20200806-20-11fv1gc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=747&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Chauvet Cave contains hundreds of cave paintings created more than 30,000 years ago.</span>
<span class="attribution"><span class="source">Thomas T/flickr</span></span>
</figcaption>
</figure>
<p>With the new IntCal20 curve, our best estimate for the creation of the oldest radiocarbon-dated painting in the cave is now 36,500 years ago. This is almost 450 years older than previously thought.</p>
<p>These are just two of many more examples of the far-reaching impact our latest work will have. </p>
<p>As <a href="https://www.cambridge.org/core/journals/radiocarbon/calibrations">the new calibration curves</a> are used to re-analyse ages of a host of archaeological and geological records, we can expect major shifts in our understanding of the planet’s past – and hopefully, a better forecast into its future. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-that-rock-hashtag-really-the-first-evidence-of-neanderthal-art-31238">Is that rock hashtag really the first evidence of Neanderthal art?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/143620/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Turney receives funding from The Australian Research Council and is a scientific advisor to cleantech graphite company, CarbonScape (<a href="https://www.carbonscape.com">https://www.carbonscape.com</a>).</span></em></p><p class="fine-print"><em><span>Alan Hogg receives funding from the Marsden fund administered by the Royal Society of New Zealand. </span></em></p><p class="fine-print"><em><span>Paula J. Reimer receives funding from the Leverhulme Trust and UK Research and Innovation. </span></em></p><p class="fine-print"><em><span>Tim Heaton receives funding from the Leverhulme Trust via a research fellowship on "Improving the Measurement of Time via Radiocarbon". </span></em></p>The updated methods are providing a clearer picture of how Earth and its inhabitants evolved over the past 60,000 years - and thus, providing new insight into its future.Christian Turney, Professor, Earth Science and Climate Change, UNSW SydneyAlan Hogg, Professor, Director, Carbon Dating Laboratory, University of WaikatoPaula J. Reimer, Chair professor, Queen's University BelfastTim Heaton, Lecturer in Statistics, University of SheffieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1412962020-06-25T20:14:17Z2020-06-25T20:14:17ZMeet the giant wombat relative that scratched out a living in Australia 25 million years ago<p>Wombats are among the most peculiar of animals. They look like a massively overgrown guinea pig with a boofy head, a waddling gait, squared-off butt, backwards-facing pouch and ever-growing molars. </p>
<p>Indeed, wombats are oddballs and don’t look much like their nearest living relatives, the koala. But koalas and wombats (collectively known as <a href="https://blogs.scientificamerican.com/tetrapod-zoology/vombatiform-radiation-part-i/">“vombatiformes”</a>) are the last survivors of a once far more diverse group of <a href="https://australian.museum/learn/species-identification/ask-an-expert/what-is-a-marsupial/">marsupials</a> whose fossil history stretches back for at least 25 million years.</p>
<p>Working out how this diverse group fizzled out to just wombats and koalas has taken centuries of extraordinary discoveries in the fossil record. We are announcing one of these today in our research <a href="https://www.nature.com/articles/s41598-020-66425-8">published in Scientific Reports</a>.</p>
<p><em>Mukupirna nambensis</em> is one of the oldest discovered Australian marsupials. Its unveiling has deepened our understanding of the relationships and evolutionary history of one of the strangest groups that once ruled this continent.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/aboriginal-australians-co-existed-with-the-megafauna-for-at-least-17-000-years-70589">Aboriginal Australians co-existed with the megafauna for at least 17,000 years</a>
</strong>
</em>
</p>
<hr>
<h2>Acupuncturing the earth</h2>
<p>In 1973 at Lake Pinpa – a small dry salt lake in South Australia – a multi-institutional expedition <a href="https://books.google.com.au/books?id=LwMkO0M1mPQC&pg=PA23&lpg=PA23&dq=dick+tedford+lake+pinpa&source=bl&ots=GgedFpuV0d&sig=ACfU3U3r3Hheo6D9PGDk6FByRV_RpwUtFA&hl=en&sa=X&ved=2ahUKEwiKs92RgZzqAhU8yjgGHRrPDrYQ6AEwAHoECAoQAQ#v=onepage&q=dick%20tedford%20lake%20pinpa&f=false">led by</a> palaeontologist Dick Tedford from the American Museum of Natural History discovered a host of extinct animals.</p>
<p>A combination of drought and strong winds had blown the sand off the surface of the lake bed, revealing the remains of animals that died after getting stuck in mud 25 million years ago. </p>
<p>One of the discoveries was a skull and partial skeleton of a large, distinctive wombat-like animal that was clearly new to science – <em>Mukupirna</em>. </p>
<p>Its fossils were found by pushing a metal rod into the clay at intervals across the lake surface, a bit like acupuncturing the skin of Mother Earth. If the rod struck something hard, the team excavated down to find what was commonly the fossilised skeleton of an otherwise unseen animal. </p>
<p>Once uncovered, they were encased in plaster shells for transport back to the Museum of Natural History, where they were subjected to years of careful preparation. Although <em>Mukupirna</em> was discovered this way in 1973, it’s only now we can formally announce this discovery to the world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=796&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=796&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=796&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1001&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1001&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343909/original/file-20200625-33557-1bz7zth.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1001&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photo shows the skull of the giant wombat relative <em>Mukupirna nambensis</em>. The front of the skull is towards the top of the photograph. The skull is 19.7cm long.</span>
<span class="attribution"><span class="source">Julien Louys, Griffith University and Robin Beck, University of Salford</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A mammoth find</h2>
<p>One of the most remarkable things about this marsupial is its large size, which we estimate was between 143-171kg, more than four times larger than any living wombat. </p>
<p>Its size inspired the scientific name <em>Mukupirna</em>, from the words <em>muku</em>, meaning “bones” and <em>pirna</em>, meaning “big”, in the Malyangapa and Dieri languages of Aboriginal people from central Australia. </p>
<p>We worked out the earliest vombatiform marsupials probably weighed about 5kg or less (about the size of a modern koala). That said, body weights of about 100kg, such as that of <em>Mukupirna</em>, then evolved independently at least six times in different branches of the family tree.</p>
<p>The biggest of these would be <em><a href="https://australian.museum/learn/australia-over-time/extinct-animals/diprotodon-optatum/">Diprotodon</a></em> at about three tonnes, the world’s largest marsupial.</p>
<h2>Behaviour up to scratch</h2>
<p><em>Mukupirna</em>‘s forearms were powerfully muscled and its hands may have worked like shovels, an attribute shared with modern wombats. Also like wombats, it was probably a good scratch-digger. But unlike today’s wombats, it probably couldn’t burrow. </p>
<p>Although <em>Mukupirna</em> was clearly herbivorous, unlike wombats its cheek teeth were low-crowned with well-developed roots. This indicates it couldn’t have survived on abrasive plant materials such as grasses, which today’s wombats consume without problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343950/original/file-20200625-33563-19b66g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australia has three endemic species of wombat: the common wombat <em>Vombatus ursinus</em> (pictured), the northern hairy-nosed wombat (<em>Lasiorhinus krefftii</em>) and the southern hairy-nosed wombat (<em>Lasiorhinus latifrons</em>).</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Pollens in the fossil deposit indicate that, unlike today, there were no grasslands in this area of central Australia back then. Instead, it was dominated by scrubby rainforest that was also home to possums, koalas and galloping kangaroos. </p>
<p>But alongside them were much stranger, more primitive animals that have left no living descendants. These included <em><a href="https://blogs.scientificamerican.com/tetrapod-zoology/vombatiforms-part-ii/">Ilaria</a></em>, which was a bit like a gigantic koala, <a href="https://museumsvictoria.com.au/collections-research/journals/memoirs-of-museum-victoria/volume-74-2016/pages-173-187/"><em>Ektopodon</em></a>, an arboreal marsupial with teeth like a cheese-grater and <a href="https://australian.museum/learn/australia-over-time/extinct-animals/wakaleo-vanderleuri/"><em>Wakaleo</em></a>, a leopard-sized marsupial lion with some of the most ferocious butchering teeth ever evolved by a mammal.</p>
<p>These forests were also punctuated by huge inland lakes that were home to lungfish, turtles, crocodiles, flamingos, ducks, stone curlews and even freshwater dolphins.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-new-species-of-marsupial-lion-tells-us-about-australias-past-88633">A new species of marsupial lion tells us about Australia's past</a>
</strong>
</em>
</p>
<hr>
<h2>A lost land</h2>
<p>By comparing different features of <em>Mukupirna’s</em> teeth and skeleton, we discovered it to be the closest known relative of modern wombats. Yet, it was as different from wombats as wombats are from koalas, which is why it has been placed in a new family of its own: the Mukupirnidae.</p>
<p>Formal recognition of <em>Mukupirna</em> fills yet another fascinating gap in our knowledge of the weird and wonderful evolutionary history of mammals on this continent. </p>
<p>Sadly, it’s likely all mukupirnids vanished when a shift in global climate triggered an environmental change from scrubby rainforests 25 million years ago, to far lusher and more biodiverse rainforests 23 million years ago. </p>
<p>This would have resulted in more intense greenhouse conditions and an environment presumably not suited to mukupirnids.</p>
<p>Hopefully this rings a warning bell about the state of Earth’s climate now. If we can’t slow the global heating we’ve triggered, how many more of Australia’s uniquely endemic living creatures will soon join <em>Mukupirna</em> in the increasingly crowded abyss of extinction?</p><img src="https://counter.theconversation.com/content/141296/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Beck has received funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Mike Archer receives funding from the Australian Research Council and the Phil Creaser CREATE Fund in UNSW. </span></em></p><p class="fine-print"><em><span>Philippa Brewer works for the Natural History Museum, London</span></em></p>The extinct Mukupirna - which translates to ‘big bones’ - is estimated to have been more than four times larger than any living wombat.Robin Beck, Lecturer in Biology, University of SalfordJulien Louys, ARC Future Fellow, Griffith UniversityMike Archer, Professor, Pangea Research Centre, UNSW SydneyPhilippa Brewer, Senior Curator, Natural History MuseumLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1400602020-06-10T04:01:04Z2020-06-10T04:01:04ZWho owns the bones? Human fossils shouldn’t just belong to whoever digs them up<p>All humans alive today can claim a common ancestral link to some hominin. Hominins include modern humans, extinct human species, and all our immediate ancestors.</p>
<p>Recent discoveries of hominin remains, including the skull of a <a href="https://theconversation.com/fossil-find-suggests-homo-erectus-emerged-200-000-years-earlier-than-thought-135068"><em>Homo erectus</em></a> in South Africa, have generated high levels of interest from the public and scientific community alike. </p>
<p>Fossils hold invaluable information about human history. But digging deeper, there is much complexity around the question of what a “fossil” is, and who should be granted ownership of them. This is the topic of our latest research article <a href="https://www.cell.com/heliyon/fulltext/S2405-8440(20)30973-7">published in the journal Heliyon</a>. </p>
<h2>Fossils fuel debate</h2>
<p>The question of what qualifies as a “fossil” remains open. The Oxford dictionary defines <a href="https://en.oxforddictionaries.com/definition/fossil,%202017">fossils</a> as: </p>
<blockquote>
<p>the remains or impressions of a plant or animal embedded in rock and preserved in petrified form. </p>
</blockquote>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/340776/original/file-20200610-82636-1286025.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dinosaur poo can become fossilised. This is called a coprolite.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>But this definition doesn’t encompass the broader use of the word. Eggshells or coprolites (fossilised excrement) are neither direct remains nor the impression of an animal or plant, but archaeologists often refer to them as “fossils”. </p>
<p>The <a href="https://www.livescience.com/37781-how-do-fossils-form-rocks.html#:%7E:text=The%20most%20common%20method%20of,the%20bones%20%E2%80%94%20are%20left%20behind.&text=These%20crystallized%20minerals%20cause%20the,with%20the%20encasing%20sedimentary%20rock.">process of fossilisation</a> can start immediately after an organism’s death, and the term “fossil” isn’t attached to a specific time period or state of preservation.</p>
<p>The term also relates to the perceived value, uniqueness or rareness of remains (and what they may reveal). Given such a breadth of meanings, it’s unsurprising attempts to regulate the status of fossils are fraught.</p>
<h2>Hands off my fossil!</h2>
<p>There was lively <a href="https://www.theguardian.com/science/2015/oct/25/discovery-human-species-accused-of-rushing-errors">debate</a> surrounding the 2015 discovery of <em><a href="https://elifesciences.org/articles/09560">Homo naledi</a></em> in the Rising Star cave near Johannesburg, South Africa. The public’s access to the site and its fossils drew heavy criticism from researchers. This raised the question: should fossil discoveries be freely available?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/340778/original/file-20200610-82636-uh3uey.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The announcement of the discovery of Homo naledi fossils in 2015 in South Africa was met with mixed responses from the research community.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/governmentza/21106873410/in/photostream/">GovernmentZA / Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Generally, around the world a person who excavates a fossil is <a href="https://journals.sagepub.com/doi/abs/10.1177/007327530704500403?journalCode=hosa">allowed to keep it</a>. Not only that, they can conduct potentially destructive analyses on it, and grant scientific and public access to the information it reveals. </p>
<p>Such practices can generate “gentleman’s club” syndrome, wherein members of scientifically influential groups have a better chance of accessing important fossils. But despite being accepted practice in the field, the “finders keepers” approach is legally problematic. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/homo-naledi-may-be-two-million-years-old-give-or-take-50416">Homo naledi may be two million years old (give or take)</a>
</strong>
</em>
</p>
<hr>
<p>Humans and human remains have a special status in most nations’ legal systems. While animals can be owned, humans can’t. Compounding this, the definition of “human” is itself contested, and this muddies the legal waters when it comes to discovering archaeological human remains. </p>
<p>For instance, recent DNA discoveries of interbreeding between <em>Homo sapiens</em>, <em><a href="https://www.nature.com/articles/nature16544">Homo neanderthalensis</a></em> and <a href="https://science.sciencemag.org/content/338/6104/222">Denisovans</a> – as well as the fact that <em>Homo naledi</em> and <em><a href="https://www.nature.com/articles/nature02999">Homo floresensis</a></em> existed at the same time as modern humans – indicates scientists struggle to reach a consensus on where the boundaries of “human” lie.</p>
<p>The definition of “human” can also be culturally ascribed. Many <a href="https://www.britishmuseum.org/sites/default/files/2019-11/Regarding-the-Dead_02102015.pdf">indigenous peoples</a> including communities from Australasia and Africa recognise an ancestral connection to species not always classified as <em>Homo sapiens</em>.</p>
<p>So what should be done with the fossilised remains of extinct species that aren’t “human” in the sense of belonging to <em>Homo sapiens</em>, but are nevertheless our evolutionary ancestors?</p>
<h2>Are human remains things to be owned?</h2>
<p>In Australia, as in most common law systems, there can be no “property” in a human corpse. While both burial and exhumation are regulated, ownership of a corpse is not.</p>
<p>The export of “Class A” cultural heritage, which includes human remains, is prohibited under the <a href="https://www.legislation.gov.au/Details/C2014C00597/Html/Text">Protection of Movable Cultural Heritage Act 1986</a>. Also, Australian state legislation regulating the scientific use of human tissue (such as the NSW <em>Human Tissue Act 1983</em>) doesn’t require any consent for samples excavated before 2003. </p>
<p>On the other hand, Australia also has a <a href="https://www.arts.gov.au/what-we-do/cultural-heritage/indigenous-repatriation">national repatriation program</a> for Indigenous cultural patrimony. This program seeks to restore stolen human remains and sacred objects to their original communities.</p>
<h2>Cultural subjects</h2>
<p>The tension between scientific interests and spiritual beliefs is apparent in the context of repatriating human remains to Indigenous communities. </p>
<p>While fossilised human remains hold significant scientific value, their symbolic and spiritual value can’t be ignored, particularly to communities that feel a connection to them. Human remains would be best described as both scientific objects and also cultural subjects.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/africas-rich-fossil-finds-should-get-the-air-time-they-deserve-91849">Africa's rich fossil finds should get the air time they deserve</a>
</strong>
</em>
</p>
<hr>
<p>Some scientists view repatriation and reburial of human remains as a deliberate destruction of a “source of information” that <a href="https://www.jstor.org/stable/280831?seq=1">belongs to global humanity</a>.</p>
<p>On the other hand, historical injustices and the imbalance of power between colonial entities and Indigenous people stand against such arguments. As a result, the repatriation and reburial of human remains becomes inseparable from broader legal arguments advanced by Indigenous peoples today.</p>
<p>Human, hominin and hominid fossils are far more than just objects to be owned. In fact, they reside at a contested and poorly regulated scientific, cultural and legal intersection.</p>
<p>We need common standards for ownership, protection and access controls. One solution would be to establish an international delegation with key stakeholders including scientists, lawyers, community representatives and policy makers. </p>
<p>Ideally, this could exist under the umbrella of the United Nations Educational, Scientific and Cultural Organisation (UNESCO). Such a body could foster constructive dialogue on how we value human fossils, and how we assign them ownership.</p><img src="https://counter.theconversation.com/content/140060/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Renaud Joannes-Boyau receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Anja Scheffers receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Alessandro Pelizzon and John Page do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>You can’t own a human, so why can you own their remains? We need to stop treating human fossils as objects.Renaud Joannes-Boyau, Senior research fellow, Southern Cross UniversityAlessandro Pelizzon, Senior lecturer, Southern Cross UniversityAnja Scheffers, Professor, Southern Cross UniversityJohn Page, Associate professor, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1329492020-03-11T16:05:27Z2020-03-11T16:05:27ZAncient bird skull found in amber was tiny predator in the time of giant dinosaurs<figure><img src="https://images.theconversation.com/files/319220/original/file-20200309-58017-occdel.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Amber holds the secret to the tiny world of the age of dinosaurs.</span> <span class="attribution"><span class="source">Xing Lida</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>Editor’s note: This article was based on a study published in the peer-reviewed journal Nature on March 11, 2020. On July 22, 2020, the journal retracted the article after other researchers raised concerns that the <a href="https://www.nature.com/articles/d41586-020-02214-7">skull belonged to a lizard, not a bird</a>. Here is the <a href="https://www.nature.com/articles/s41586-020-2553-9">retraction note</a> from the paper’s authors</em>:</p>
<p><em>We, the authors, are retracting this Article to prevent inaccurate information from remaining in the literature. Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis regarding the phylogenetic position of HPG-15-3.</em></p>
<hr>
<p>In 2016, our colleague Xing Lida held up a small piece of polished, deeply yellow amber. As sunlight shone through the ancient resin, Lida saw the outline of a pristinely preserved, amazingly small skull. There was a prominent eye socket, a dome-shaped crown of the head, a long, tapering snout and even small teeth. It was bird-like, but in a strange and ancient way.</p>
<p>The amber contains the skull of <em>Oculudentavis khaungraae</em>, a <a href="https://www.nature.com/articles/s41586-020-2068-4">newly described dinosaur</a> and one of the smallest ever discovered. Its tiny stature is forcing paleontologists to rethink the lower limits of body size in birds, and the nearly 100-million-year-old fossil is challenging the current understanding of when and how dinosaur giants shrank into the birds of today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319728/original/file-20200310-61066-1ccn5yd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The piece of amber measures only 1.25 inches (31.5 millimeters) in length. The skull is a mere 0.6 inches (11 millimeters).</span>
<span class="attribution"><span class="source">Xing Lida</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A mysterious transformation</h2>
<p>The <a href="https://theconversation.com/take-a-t-rex-and-a-chicken-and-youll-see-how-dinosaurs-shrank-survived-and-evolved-into-birds-29996">evolutionary transition of dinosaurs to modern birds</a> is one of the most astounding transformations in the history of life: large, bipedal and mostly carnivorous dinosaurs morphed into small, flying birds. Famous discoveries like <em><a href="https://theconversation.com/how-we-discovered-a-new-species-of-the-missing-link-between-dinosaurs-and-birds-102363">Archaeopteryx</a></em> and more recently the fossils from the <a href="https://jhupbooks.press.jhu.edu/title/birds-stone">Jehol Biota in China</a> have given researchers some hints about the process. But finds from this <a href="https://www.quantamagazine.org/how-birds-evolved-from-dinosaurs-20150602">evolutionary phase</a> – which researchers think began about 200 million years ago – are rare.</p>
<p>Paleontologists are far from having a complete picture of the evolution of birds, and even farther from a full inventory of Earth’s ecosystems in the age of dinosaurs. Our research on the tiny <em>Oculudentavis</em>, published in the journal Nature, adds valuable information to the puzzle of when, how and to what extent dinosaurs shrank.</p>
<h2>Clues in bone</h2>
<p>Our team needed to see the minute details of the skull, and we needed to do it without cracking or ruining the specimen - a difficult task with a skull encased in 99-million-year old amber from Myanmar. To do that, we scanned the skull with high-resolution X-rays and created a digital model with very fine anatomical detail. What emerged was a picture of an overall bird-like anatomy. But in some interesting ways, <em>Oculudentavis</em> is unlike any bird or dinosaur that has ever been found.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319218/original/file-20200309-118951-1umgcvv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This high-resolution scan allowed us to see the intricacies of a bone structure unlike any before seen in birds or dinosaurs.</span>
<span class="attribution"><span class="source">Xing Lida</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The obvious curiosity of the fossil is its size: <em>Oculudentavis</em> rivaled the smallest bird living today, the bee hummingbird, and likely was no more than 1.6 inches (4 centimeters) from beak to tail. We considered whether the skull possibly belonged to a very young animal, but the extent and pattern of bone growth and the proportional size of the eye pointed to a mature bird.</p>
<p>With a total skull length of just about 0.6 inches (1.5 centimeters), <em>Oculudentavis</em> pushes against what is considered the lower limit of size in birds: the head still had to hold functional eyes, a brain and jaws. The small size is especially surprising if one considers that <em>Oculudentavis</em> lived during the same time as <a href="https://svpow.com/2017/08/09/dont-believe-the-hype-patagotitan-was-not-bigger-than-argentinosaurus/">giant plant-eating dinosaurs like <em>Argentinosaurus</em></a>.</p>
<h2>Small and specialized</h2>
<p>The small size of <em>Oculudentavis</em> is striking, but to a trained eye there are other extremely unusual features, too.</p>
<p>First of all, the skull seems to be built for strength. The bones show an unusual pattern of fusion and the skull lacks an antorbital fenestra, a small hole often found in front of the eye.</p>
<p>The eyes of <em>Oculudentavis</em> also surprised us. The shape of the bones found within the eye, the scleral ossicles, suggests that it probably had conical eyes with small pupils. This type of eye structure is especially well adapted for moving around in bright light. While daytime activity might be expected for an <a href="https://www.nationalgeographic.com/science/phenomena/2011/04/14/dinosaurs-around-the-clock-or-how-we-know-velociraptor-hunted-by-night/">ancient bird from the age of dinosaurs</a>, the shape of the ossicles is entirely distinct from any other dinosaur and resembles those of modern-day lizards.</p>
<p>Adding to the list of unexpected features, the upper jaw carries at least 23 small teeth. These teeth extend all the way back beneath the eye and are not set in deep pockets, an unusual arrangement for most ancient birds. The large number of teeth and their sharp cutting edges suggest that <em>Oculudentavis</em> was a predator that may have fed on small bugs.</p>
<p>The sum of these traits – a strong skull, good eyesight and a hunter’s set of teeth – suggests to us that <em>Oculudentavis</em> led a life previously unknown among ancient birds: it was a hummingbird-sized daytime predator.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=477&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=477&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=477&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319731/original/file-20200310-61076-1p3vudc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tiny <em>Oculudentavis</em> may have occupied a unique ecological niche in the ancient world.</span>
<span class="attribution"><span class="source">Han Zhixin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>One of the earliest and tiniest birds?</h2>
<p>Placing <em>Oculudentavis</em> in the tree of life is, given its strange anatomy, challenging. Our phylogenetic analysis – the investigation of its relationships to other dinosaurs – identifies <em>Oculudentavis</em> as one of the most ancient birds. Only <em>Archaeopteryx</em> branched off earlier. </p>
<p>Scientists consider the nectar-feeding hummingbirds – <a href="https://www.allaboutbirds.org/news/ancient-hummingbirds-in-surprising-places/">which appeared 30 million years ago</a> – the smallest dinosaurs on record. But if our placement of <em>Oculudentavis</em> holds true, the miniaturization of dinosaurs may have peaked far earlier than paleontologists previously thought. In fact, the largest and the smallest dinosaurs may have walked and flown the same earth nearly 100 million years ago.</p>
<p>Our work demonstrates how little scientists know about the little things in the history of life. Scientists’ snapshot of fossil ecosystems in the dinosaur age is incomplete and leaves so many questions unanswered. But paleontologists are eager to take on these questions. What other tiny species were out there? What was their ecological function? Was <em>Oculudentavis</em> the only visually guided bug hunter? To better understand the evolution of the diversity of life we need more emphasis and recognition of the small.</p>
<p>Amber holds strong potential to fill that gap. Maybe one day a scientist will hold up another piece, and let sunshine reveal a complete <em>Oculudentavis</em>, or even a previously unknown species. More finds in amber will help illuminate the world of the tiny vertebrates in the age of dinosaurs.</p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklysmart">You can get our highlights each weekend</a>.]</p><img src="https://counter.theconversation.com/content/132949/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The skull of Oculudentavis, found encased in amber, provides new clues into the transition from dinosaurs to birds and may be smallest of either ever found.Lars Schmitz, Associate Professor of Biology, Scripps CollegeJingmai Kathleen O'Connor, Senior Professor of Paleontology, Chinese Academy of SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1302152020-01-30T06:47:23Z2020-01-30T06:47:23ZFossil footprints show how life endured amid volcanic eruptions 183 million years ago<figure><img src="https://images.theconversation.com/files/310848/original/file-20200120-69559-9qh8iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reconstruction of the ancient environment at the Highlands trace fossil site about 183 million years ago. </span> <span class="attribution"><span class="source">Artwork by Akhil Rampersadh. Heterodontosaurid silhouette is courtesy of Viktor Radermacher.</span></span></figcaption></figure><p>Fossil footprints provide a special source of scientific evidence. They reveal how animals walked and how large they were. In some cases where there are no body fossils like bones, trace fossils such as footprints or trackways may be the only evidence that animals were present in an ancient environment. </p>
<p>In <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">our new publication</a>, using techniques that have been honed by ichnologists – those who study trace fossils – we examined the trackways of land-dwelling vertebrates in what is today a farm in the centre of South Africa. These fossil trackways are preserved in sandstones within a thick pile of basaltic lava flows. They offer rare insights about ancient life in a stressful, hostile environment some 183 million years ago in the Early Jurassic.</p>
<p>This <a href="http://stratigraphy.org/index.php/ics-chart-timescale">geological epoch</a> is probably best known in the public imagination as the dawn of the age of the dinosaurs. Towards the end of the Early Jurassic, a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">major geological event devastated life</a>, especially in the oceans.</p>
<p>This mass extinction event was caused by, among other things, the degassing of the extensive lava flows that poured out during volcanic eruptions in the southern part of the <a href="https://www.livescience.com/37285-gondwana.html">supercontinent Gondwana</a>. These volcanic eruptions changed the chemistry of the ancient atmosphere and oceans at the time.</p>
<p>But in between the voluminous volcanic eruptions, the environment and life in it occasionally recovered. It was during these intermittent periods that the movement of animals across the land surface could be captured as the fossil trackways we study today. </p>
<p>These ancient footprints are important because they tell us about the type of Early Jurassic animal life, and because the tracks bring together different earth science disciplines that can help us visualise what the ancient world looked like.</p>
<h2>Reconstructing a landscape</h2>
<p>There was more to our research than just reconstructing what individual animal species were and how they moved. We also had to reconstruct the ancient environment in which these animals lived. For this we had to incorporate existing findings from different academic disciplines.</p>
<p>Geologists, including stratigraphers, volcanologists, geochronologists and sedimentologists, as well as palaeontologists, palaeobotanists and others, were all involved in studying these rocks before us. They gathered evidence about the properties of the sedimentary rocks that host the tracks; the plant fossils associated with these rocks; and the age, composition and structure of the ancient lava flows that entombed the track-bearing sediment surface.</p>
<p>Drawing from this existing research and our own work, our collective observations show that when vast sheets of lava flowed across the landscape, the environment turned into a land of fire. But during the quieter periods life returned to normal: streams ran, the sun shone, plants grew and the animals, among them dinosaurs, grazed and hunted. </p>
<p>What emerges is a picture not just of devastation wrought by volcanic eruptions, but one of a functioning ecosystem that endured despite environmental threats.</p>
<h2>A new ichnospecies</h2>
<p>Our research also unearthed a new species of dinosaur footprint. The best-preserved trackways at the Highlands farm site were made by dinosaurs – both meat-eating ones which walked on two legs, as well as plant-eating ones which walked on four legs. Less well-preserved trackways are more difficult to interpret. But those we studied appear to have been potentially made by <a href="https://nasmus.co.za/palaeontology/">synapsids</a>, a group of reptiles that are considered to be the ancestors of mammals. The synapsids have <a href="https://theconversation.com/why-south-africas-karoo-is-a-palaeontological-wonderland-43045">a rich skeletal record</a> in South Africa. </p>
<p>To identify the trackmakers, we carefully compared the morphology of the tracks – for example the shape, size and angles between the toe impressions – to other known tracks around the world. Some had characteristics common in footprints made by theropods, a group of carnivorous dinosaurs. But some showed features known only in tracks of ornithischians, a group of herbivorous dinosaurs. </p>
<p>We then closely compared our observations to those previously reported, and were able to come up with a list of diagnostic features that define the new ichnospecies. We named it after a French priest and trace fossil expert, Dr Paul Ellenberger, who is considered <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">the father of vertebrate ichnology</a> in southern Africa. </p>
<h2>Significance of the South African fossil heritage</h2>
<p>South Africa is a global epicentre for palaeontology. <a href="https://theconversation.com/five-reasons-why-2018-was-a-big-year-for-palaeontology-106725">Discoveries</a> made in the country have showcased some of the first animals to walk on land, some of the first mammals, the first turtles, early dinosaurs, and hominids. </p>
<p>But the country’s famous fossils only truly help us understand the history of life on Earth if their geological and palaeoenvironmental contexts are also described. Placed in their ancient environmental setting, these Early Jurassic trackways show that some animal life was resilient even as the environment changed and was hit by catastrophic events.</p><img src="https://counter.theconversation.com/content/130215/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emese M Bordy receives funding from the Centre of Excellence in Palaeosciences (COE-PAL National Research Foundation-DST), the National Research Foundation of South Africa and the University of Cape Town.</span></em></p>These trackways offer rare insights about ancient life in a stressful, hostile environment during the Early Jurassic.Emese M Bordy, Associate Professor in Geological Sciences, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1243282019-09-27T14:53:27Z2019-09-27T14:53:27ZOcean ecosystems take two million years to recover after mass extinction – new research<figure><img src="https://images.theconversation.com/files/294564/original/file-20190927-185369-1dgaqhm.jpg?ixlib=rb-1.1.0&rect=18%2C657%2C4160%2C2895&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A phytoplankton bloom stretching across the Barents Sea off the coast of mainland Europe's most northern point.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Phytoplankton_bloom_captured_by_Envisat.jpg">European Space Agency</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Around 66m years ago, a giant asteroid struck the Earth, causing the <a href="https://science.sciencemag.org/content/327/5970/1214">extinction of the dinosaurs</a>, ammonites, and many other species.</p>
<p>The asteroid was equally devastating at a microscopic level, <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/33/8/653/103785">driving ocean plankton</a> to near-extinction. This crippled the base of the marine food chain and shut down important ocean functions, such as <a href="https://pubs.geoscienceworld.org/gsa/geology/article/44/4/287/132044/partial-collapse-of-the-marine-carbon-pump-after">the absorption and delivery of carbon dioxide</a> from the atmosphere to the ocean floor.</p>
<p>Given the <a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">real threat of a sixth mass extinction event</a> brought about by human-caused climate breakdown and habitat disruption, we wanted to find out how long the ocean ecosystem took to reboot after the last one. What we found has grave implications for the long-term outlook of marine ecosystems should we tip the critical base of its food chain over the threshold of extinction.</p>
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<p>
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Read more:
<a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">Earth's sixth mass extinction has begun, new study confirms</a>
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<p>The nannoplankton almost totally wiped out 66m years ago – also known as <a href="https://www.palaeontologyonline.com/articles/2018/fossil-focus-calcareous-nannofossils-the-best-things-are-microscopic/">coccolithophores</a> – are now widespread once more in the sunlit upper oceans. Although roughly 100 times smaller than a grain of sand, they are so abundant that they are <a href="https://www.wired.com/2010/08/phytoplankton-blooms-gallery/">visible from space as swirling blooms</a> in the ocean surface.</p>
<p>When these microscopic plankton die, they leave behind exquisite armoured <a href="http://www.mikrotax.org/Nannotax3/index.php?id=315">exoskeletons known as coccospheres</a> made from the mineral calcite, composed of bonded calcium and carbon. Along with the dead plankton cells, these skeletons slowly fall to the ocean floor, forming a muddy calcium and carbon-rich sediment. As this sediment compacts, it forms chalk and limestone, leaving us with iconic landscapes such as <a href="https://youtu.be/Ep5tcBXyFoE">white chalk cliffs</a> – the shallow sea floor of a forgotten age, since lifted up by tectonic activity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The white chalk cliffs of England’s coast contain within them millions of years of plankton history.</span>
<span class="attribution"><span class="source">Jeremy Young</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Conserved within this compacted sediment is a continuous fossil record stretching back 220m years. It is this fossil record – the <a href="http://disq.us/t/3iipu4d">most abundant on the planet</a> – that can tell us how ecosystems responded to the extinction of nannoplankton. Changes in the diversity and abundance of the plankton that once lived in the ocean above reflect the environmental changes that played out in the millennia after the giant asteroid hit.</p>
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<strong>
Read more:
<a href="https://theconversation.com/sea-plankton-shells-hold-key-to-millions-of-years-of-climate-data-19589">Sea plankton shells hold key to millions of years of climate data</a>
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<p>We extracted a continuous <a href="http://www-odp.tamu.edu/publications/198_IR/chap_05/chap_05.htm">core</a> of deep-sea sediment from the Pacific Ocean. For the first 13m years after the <a href="http://www-odp.tamu.edu/publications/198_IR/chap_05/c5_f4.htm">mass extinction</a> event, we took a sample of the fossil record at intervals of 13,000 years. We measured fossil abundance, diversity and cell sizes from over 700,000 specimens, producing probably the largest fossil dataset ever produced from a single site.</p>
<h2>2m years for stability, 10m for diversity</h2>
<p>These <a href="http://disq.us/t/3iipu4d">fossil data</a> revealed that the plant-like, photosynthetic plankton bounced back almost immediately - probably within a few thousand years after the mass extinction. However, the earliest communities were highly unstable and made up of just a handful of species with unusually small cell sizes, as the figure above shows.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1089&fit=crop&dpr=1 600w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1089&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1089&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1369&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tiny interlocking discs combine to produce microplankton’s calcite shells. Species that survived the asteroid impact were much bigger than new species that emerged in the place of those that were wiped out.</span>
<span class="attribution"><span class="source">Paul Bown/UCL</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While the calcite skeletons of larger plankton cells can <a href="https://www.mdpi.com/2071-1050/10/3/869">sink to the sea floor</a>, the skeletons of these smaller organisms descend much less often, instead getting “recycled” in the upper ocean by hungry plankton. Communities with larger cell sizes were not reestablished until two million years later, restoring their critical transfer of carbon to the ocean floor to <a href="https://pubs.geoscienceworld.org/gsa/geology/article/44/4/287/132044/partial-collapse-of-the-marine-carbon-pump-after">pre-extinction levels</a>.</p>
<p>By this time, the number of different plankton species had also increased. This genetic diversity allowed them to expand into a greater range of ocean habitats, providing greater resilience to environmental change, and a secure foundation at the base of the ocean food web. </p>
<p>This stability then supported expansion in the abundance and diversity of larger plankton, fish, mammals, and birds dependent on these food sources. But although stable and resilient ecosystems had returned by two million years after the mass extinction, it took a further eight million years for species numbers to fully recover to their previous levels.</p>
<h2>A warning from the past</h2>
<p>Today’s marine ecosystems are still just as dependent on the plankton at their base as they were in the past. Studies show that populations of modern-day plankton have already <a href="https://www.nature.com/articles/nature09268">declined by as much as 40%</a>, and that 70% of species are <a href="https://www.pnas.org/content/113/11/2964">migrating towards the poles</a>. We still don’t fully understand how plankton species might finally be driven to extinction, but the fossil record shows us that <a href="https://science.sciencemag.org/content/332/6027/349">extinction is strongly shaped by climate change</a>.</p>
<p>If we carry on emitting carbon and interfering with marine ecosystems, we run the risk of losing one of its critical carbon-storing and food-providing players. Research shows that that could take nature millions of years to reverse. </p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1124328">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/124328/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Bown receives funding from University College London and the Natural Environment Research Council (NERC).
</span></em></p><p class="fine-print"><em><span>Samantha Gibbs receives funding from The Royal Society, the University of Southampton and the Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Sarah Alvarez receives funding from the European Union's Environment Research Council (NERC).</span></em></p>Populations of plankton are in decline. If we push this critical foundation of the marine food chain to extinction, we could cripple ecosystems for millions of years.Paul Bown, Professor of Micropalaeontology, UCLSamantha Gibbs, Lecturer, National Oceanography Centre, University of SouthamptonSarah Alvarez, Lecturer in Life and Earth Sciences, University of GibraltarLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1219332019-09-23T11:34:43Z2019-09-23T11:34:43ZClimate change created today’s large crocodiles<figure><img src="https://images.theconversation.com/files/293422/original/file-20190920-135074-1rqz55p.jpg?ixlib=rb-1.1.0&rect=260%2C201%2C4280%2C3049&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When is bigger better?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/saltwater-amercan-crocodile-closeup-underwater-shot-1149378311">Willyam Bradberry/Shutterstock.com</a></span></figcaption></figure><p>What does the term crocodylian bring to mind? A big reptile with a chomping jaw? </p>
<p>Crocodylians are the 27 species of crocodiles, alligators, caimans and gharials that live all over Earth today, except for in <a href="https://www.nationalgeographic.org/maps/crocodilian-ranges/">Europe and Antarctica</a>. There are some smaller species, but these top predators are usually big, at least 2 meters long. They also share a general shape and look – for instance, how easily can you <a href="https://www.livescience.com/32144-whats-the-difference-between-alligators-and-crocodiles.html">tell an alligator and a crocodile apart</a>?</p>
<p>The fossil record of crocodylians is much richer, though, with many different forms and body sizes and extraordinary ecological diversity.</p>
<p>Over their long evolutionary history of more than 200 million years, crocs experimented with different lifestyles, as well as various body lengths. But exactly which environmental factors might have influenced the body sizes of crocs throughout their evolution? And does the body size of crocs suggest something about past species’ extinction?</p>
<p>To investigate, my colleagues and I <a href="https://doi.org/10.1186/s12862-019-1466-4">created a complete map of body sizes of crocs</a> through time. Body size can reveal a lot about the biology of extinct animals. Our study was the first to apply some modern computational methods to understand body size evolution in crocs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293379/original/file-20190920-135109-1t3cxq4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some ancient crocs were giants. See the human diver in this illustration for scale.</span>
<span class="attribution"><a class="source" href="https://en.m.wikipedia.org/wiki/File:Machimosaurus_illustration.jpg">M.T. Young et al/Dmitry Bogdanov/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Looking for size patterns in the fossil record</h2>
<p>The <a href="https://ucmp.berkeley.edu/taxa/verts/archosaurs/crocodylomorpha.php">Crocodylomorpha</a> group includes all extinct relatives of the modern crocodylians – more than 400 species in total. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=563&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=563&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=563&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=707&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=707&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293378/original/file-20190920-135097-6nxnwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=707&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Compare a small herbivore croc called <em>Simosuchus</em> to the size of a modern human.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Simosuchus_scale.svg">Smokeybjb/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Extinct crocodylomorphs – henceforth “crocs” – ranged from <a href="https://www.palaeontologyonline.com/articles/2018/fossil-focus-thalattosuchia/?doing_wp_cron=1565897712.1040780544281005859375">marine forms</a> who lived a fully aquatic life to <a href="https://www.nationalgeographic.com/science/2019/06/ancient-crocodile-cousins-evolved-to-eat-plants-fossil-teeth-show/">terrestrial herbivores</a> with complex teeth that look like those seen in mammals today. There’s much more ecological diversity on display in the fossil record than what you see in modern crocodylians.</p>
<p>The oldest crocs, alive during the <a href="https://www.livescience.com/43295-triassic-period.html">Triassic Period</a>, were small, rarely more than 1 meter long. </p>
<p>At first glance, the fossil record might seem to suggest that crocs evolved from this small start to be larger over time. That would fit with a general trend biologists have identifed: Animals tend to evolve over time to be bigger. This pattern is known as <a href="https://theconversation.com/sea-creatures-will-get-bigger-and-bigger-if-we-dont-eat-them-first-37815">Cope’s rule</a>. Scientists have spotted this tendency in <a href="https://science.sciencemag.org/content/280/5364/731">mammals</a>, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1420-9101.2004.00870.x">dinosaurs</a> and <a href="https://www.nature.com/articles/ncomms4567">pterosaurs</a>.</p>
<p>To see whether this rule holds for crocs, my collaborators and I pulled together data on almost 200 species, more than in any other croc body-size study.</p>
<p>Since paleontologists don’t know the exact size of most extinct animals, this kind of study frequently estimates body size based on a measurement of one part of the animal. In our case, we used skull length as a proxy for total body size.</p>
<p>We collected most of the data (for nearly 120 species) by measuring specimens during visits to museum collections around the world, from South America to China. The remaining information came from other researchers’ photographs or figures in the scientific literature.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=207&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=207&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=207&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=261&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=261&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293384/original/file-20190920-135097-18c3xqo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=261&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left, a big <em>Kaprosuchus</em> skull in the paleontological collection at the University of Chicago. Right, a tiny <em>Gondwanasuchus</em> skull at the Paleontology Research Center, Peirópolis, Brazil.</span>
<span class="attribution"><span class="source">Pedro L. Godoy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Factors that influence size</h2>
<p>Our analyses show no evidence that crocs played by Cope’s rule: They don’t seem to have evolved to become bigger over time. </p>
<p>Instead, we saw a much more complex scenario, with multiple changes of average body size as various subgroups evolved and went extinct. Why?</p>
<p>One important clue appeared when we analyzed how body size changes across different lifestyles.</p>
<p>We divided crocs into three ecological categories: land-based, semi-aquatic and fully aquatic. We found that terrestrial crocs are significantly smaller than semi-aquatic and marine ones. Other researchers have documented similar findings for mammals, with <a href="https://www.sciencemag.org/news/2018/03/sea-mammals-are-huge-reason">marine species larger than their terrestrial relatives</a>. Think of walruses and sea lions, which are much bigger than their cousins: cats, wolves and dogs.</p>
<p>One explanation for this might be the adaptations that are necessary for life in the aquatic realm. For example, having a large body might help <a href="https://www.eurekalert.org/pub_releases/2018-03/su-srl032218.php">maintain an optimal temperature in the water</a>.</p>
<p>We also investigated whether environmental factors – temperature and geographical distribution – had an influence on croc body size.</p>
<p>At first, we did our analyses with all 195 crocs and found no strong link between these factors and size. But when we subdivided the species into smaller subgroups, we found some interesting results.</p>
<p>One of these subgroups is Crocodylia, which includes modern crocodylians and only their closest extinct relatives. They lived mostly during the <a href="https://www.livescience.com/40352-cenozoic-era.html">Cenozoic</a> – that’s our current era which began after the <a href="https://www.nationalgeographic.com/science/prehistoric-world/dinosaur-extinction/">extinction of nonavian dinosaurs</a> 66 million years ago.</p>
<p><iframe id="IUZuy" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/IUZuy/5/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>For Crocodylia, we found that larger sizes tend to be found with lower temperatures. This might seem counterintuitive, because <a href="http://www.gardinitiative.org/">crocs and other reptiles like warmer places</a>. But the way we interpreted this result is that, as the Earth got cooler, the areas crocs could live in got more restricted. This could have increased competition in their habitats and perhaps larger crocs were more successful. In the end, lower temperatures probably led smaller crocs to extinction.</p>
<h2>A more nuanced picture of evolving size</h2>
<p>There are two take-home messages from this discovery.</p>
<p>First, scale matters. When we analyzed all crocs together, we did not find significant correlations. But when we focused on a specific group (Crocodylia), at a shorter period of time (only the Cenozoic), we found interesting results.</p>
<p>The second is that climate change can shape the evolution of species. This is pretty obvious, and <a href="https://science.sciencemag.org/content/348/6234/571.full">previous studies have shown it for other animals</a>. In the case of crocs, climate change – the cooling temperatures during the Cenozoic – probably contributed to the comparatively large sizes of today’s species. Crocs became more restricted to the tropics and this possibly led to the extinction of smaller species. </p>
<p>In the end, the large size of modern crocs, although a symbol of strength and power, might mean that this group is instead ecologically fragile, facing a long-term process of extinction. And today, the few croc species left are facing an extra challenge related to environmental changes, this time due to <a href="https://www.theguardian.com/environment/2015/sep/08/human-activity-driving-half-of-worlds-crocodile-species-to-extinction">human-made destruction of their ecosystems</a>.</p><img src="https://counter.theconversation.com/content/121933/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pedro L. Godoy receives funding from the National Science Foundation through its Division of Environmental Biology.</span></em></p>Paleontologists created an evolutionary map of how croc body size changed over the last 200 million years – with some interesting implications for today’s species.Pedro L. Godoy, Postdoctoral research associate, Stony Brook University (The State University of New York)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1184522019-06-13T03:07:36Z2019-06-13T03:07:36ZA giant species of trilobite inhabited Australian waters half a billion years ago<figure><img src="https://images.theconversation.com/files/278774/original/file-20190611-52767-o6xd9p.jpg?ixlib=rb-1.1.0&rect=269%2C128%2C1515%2C877&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fossil of the giant new trilobite species _Redlichia rex_.
</span> <span class="attribution"><span class="source">James Holmes</span>, <span class="license">Author provided</span></span></figcaption></figure><p>At up to 30cm long and armed with spines for crushing and shredding food, we’ve identified a previously unknown creature that would have been a giant among its neighbours in the waters off modern-day South Australia.</p>
<p>The newly described fossil of a trilobite – known as <em>Redlichia rex</em> – is detailed in a <a href="https://www.tandfonline.com/doi/full/10.1080/14772019.2019.1605411" title="The trilobite Redlichia from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia: systematics, ontogeny and soft-part anatomy">paper out this week in the Journal of Systematic Palaeontology</a>.</p>
<p>There is even evidence this monster of the ancient sea could have been a cannibal, feeding on its own kind.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-are-humans-going-to-evolve-again-116990">Curious Kids: are humans going to evolve again?</a>
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<p>Trilobites are related to modern-day <a href="https://australianmuseum.net.au/learn/animals/crustaceans/">crustaceans</a> (such as crabs and lobsters) and insects, and are some of the oldest animals to appear in the fossil record. </p>
<p>Because of their abundance, trilobites are considered a model group for understanding the <a href="https://theconversation.com/life-quickly-finds-a-way-the-surprisingly-swift-end-to-evolutions-big-bang-110984">Cambrian explosion</a> – the sudden appearance about 540 million years ago of almost all major animal groups on Earth.</p>
<p>Trilobites first appeared around 520 million years ago and lasted for about 270 million years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=563&fit=crop&dpr=1 600w, https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=563&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=563&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=708&fit=crop&dpr=1 754w, https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=708&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/278452/original/file-20190607-97989-vcn3y3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=708&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration of the Cambrian seafloor with the trilobite <em>Redlichia rex</em> in the foreground.</span>
<span class="attribution"><span class="source">Katrina Kenny</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Exceptional fossil deposits</h2>
<p>Our most important understanding of life around the time of the Cambrian explosion comes from a series of rare, exceptional fossil deposits called <em>Konservat-Lagerstätten</em> (German for “conservation storage-place”).</p>
<p>These deposits preserve not only the hard parts of organisms such as shells, but also the soft parts such as eyes, muscles and guts. The most famous of these is the <a href="https://burgess-shale.rom.on.ca/en/">Burgess Shale</a> from Canada, although a number of other similar deposits have been discovered in places such as China and Greenland. </p>
<p>Australia also boasts one of these deposits – the only one in the Southern Hemisphere. It is called the Emu Bay Shale and is found on Kangaroo Island in South Australia.</p>
<p>The most common fossils within the Emu Bay Shale are <a href="https://australianmuseum.net.au/learn/australia-over-time/fossils/what-are-trilobites/">trilobites</a>.</p>
<h2>The latest find</h2>
<p>In our <a href="https://www.tandfonline.com/doi/full/10.1080/14772019.2019.1605411" title="The trilobite Redlichia from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia: systematics, ontogeny and soft-part anatomy">study</a>, we describe a very large new trilobite from the Emu Bay Shale. It’s one of the largest trilobites known from the Cambrian Period.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=331&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=331&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=331&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=417&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=417&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279262/original/file-20190613-32321-10alvvm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=417&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A large specimen of the newly described trilobite <em>Redlicha rex</em> from the Emu Bay Shale compared to a 20c coin.</span>
<span class="attribution"><span class="source">James Holmes/University of Adelaide</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Due to its exceptional size and armament, we decided <em>Redlichia rex</em> would be an appropriate name. This is reminiscent of the name <em>Tyrannosaurus rex</em> – <em>rex</em> means “king” in Latin. The <em>Redlichia</em> part of the name is the genus (the same as <em>Homo</em> in <em>Homo sapiens</em>), originally named in 1902 after palaeontologist Karl Redlich.</p>
<p>Because the Emu Bay Shale preserves the soft parts of organisms, we find the appendages (or legs) of trilobites preserved as well as the hard shell. These soft parts are extremely rare – complete appendages are known for only six of the more than <a href="https://www.trilobites.info/">20,000</a> described species.</p>
<p>What is even more special about the Emu Bay Shale examples is that because <em>Redlichia rex</em> was so big, the appendages are also very large, making them easier to look at in detail.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279272/original/file-20190613-32321-74pvwf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A graphic reconstruction of the <em>Redlichia rex</em> appendage used for shredding and crushing prey.</span>
<span class="attribution"><span class="source">Katrina Kenny</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The most important feature of these is an enlarged inner side of the base of each pair of legs, which was covered in short, robust spines and worked as a nutcracker. </p>
<h2>Carnivores of the sea</h2>
<p>Unlike those of other trilobites, the morphology of the spines suggests they may have been adapted to crushing shells of other Cambrian animals. If this were the case, the most likely food <em>Redlichia rex</em> would have been eating was other trilobites. </p>
<p>In the Emu Bay Shale, we also find what are called coprolites, or fossilised poo. In these we find pieces of crushed-up trilobite.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=253&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=253&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=253&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=318&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=318&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279267/original/file-20190613-32361-1efpead.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=318&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Crushed-up pieces of trilobite were found in the coprolites, the fossilised poo.</span>
<span class="attribution"><span class="source">James Holmes</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It was originally thought poo fossils such as these were produced by the giant Cambrian predator <a href="https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/600-million-years/videos/understanding-anomalocaris/index.html"><em>Anomalocaris</em></a> – a metre-long beast with two strange claws in the head and a circular, vampire-toothed mouth. But it now seems likely that <em>Redlichia rex</em> produced some of these.</p>
<p>Consistent with this idea, some specimens of <em>Redlichia rex</em> show injuries resulting from attack. These may also be from <em>Anomalocaris</em>, although it is possible that <em>Redlichia rex</em> indulged in cannibalism, or took part in territorial battles (as is seen in modern lobsters).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/life-quickly-finds-a-way-the-surprisingly-swift-end-to-evolutions-big-bang-110984">Life quickly finds a way: the surprisingly swift end to evolution's big bang</a>
</strong>
</em>
</p>
<hr>
<p>Once animals began to eat each other, the selective pressure to adapt methods to prevent being eaten would have been very high. This is almost certainly the reason why hard shells evolved in the Cambrian – for protection against predation.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/j-nTk11UoVY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Lobsters caught battling it out today.</span></figcaption>
</figure>
<p>The result would have been an evolutionary arms race between predators and prey, with each developing more efficient ways of defence and attack, such as the development of shell-crushing abilities in certain animals.</p>
<p>The formidable appendages of <em>Redlichia rex</em> are probably a result of this, and this giant trilobite was likely a source of terror for small creatures on the Cambrian seafloor.</p><img src="https://counter.theconversation.com/content/118452/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James D. Holmes receives funding from the Australian Government via an RTS PhD scholarship and from the University of Adelaide.</span></em></p><p class="fine-print"><em><span>Diego C. García-Bellido receives funding from Australian Research Council, National Geographic Society and Spanish Ministry of Science. </span></em></p><p class="fine-print"><em><span>John Paterson receives funding from the Australian Research Council and National Geographic. </span></em></p>There is evidence to show this monster of the ancient sea was a cannibal, feeding on its own kind.James D. Holmes, Palaeontology PhD student, University of AdelaideDiego C. García-Bellido, Associate Professor, University of AdelaideJohn Paterson, Professor of Earth Sciences, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1126722019-03-29T14:56:28Z2019-03-29T14:56:28ZLast of the giants: What killed off Madagascar’s megafauna a thousand years ago?<figure><img src="https://images.theconversation.com/files/265740/original/file-20190325-36264-n5hk55.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A modern mouse lemur *Microcebus* sits upon the cranium of an extinct *Megaladapis* lemur.</span> <span class="attribution"><a class="source" href="https://www.daovanhoang.com">Dao Van Hoang www.daovanhoang.com</a></span></figcaption></figure><p>Giant 10-foot-tall elephant birds, with eggs eight times larger than an ostrich’s. Sloth lemurs bigger than a panda, weighing in at 350 pounds. A puma-like predator called the giant fosa.</p>
<p>They sound like characters in a child’s fantasy book, but along with dozens of other species, they once really roamed the landscape of Madagascar. Then, after millions of years of evolution in the middle of the Indian Ocean, the populations crashed in just a couple of centuries.</p>
<p>Scientists know that over the past 40,000 years, most of Earth’s megafauna – that is, animals human-size or larger – have gone extinct. Woolly mammoths, sabre tooth tigers and countless others no longer roam the planet.</p>
<p>What’s remarkable about the megafaunal crash in Madagascar is that it occurred not tens of thousands of years ago but just over 1,000 years ago, between A.D. 700 and 1000. And while some small populations survived a while longer, the damage was done in a relatively short amount of time. Why?</p>
<p>Over the last three years, new investigations into climate and land use patterns, human genetic diversity on the island and the dating of hundreds of fossils have fundamentally changed scientists’ understanding of the human and natural history of Madagascar. <a href="https://scholar.google.com/citations?user=M6TfcNkAAAAJ&hl=en&oi=ao">As two</a> <a href="https://scholar.google.com/citations?user=DUkXIeAAAAAJ&hl=en&oi=ao">paleoclimatologists and</a> <a href="https://scholar.google.com/citations?user=wAfh3EYAAAAJ&hl=en&oi=ao">a paleontologist</a>, we brought together this research with new evidence of megafaunal butchery. In doing so we’ve created <a href="https://doi.org/10.1016/j.jhevol.2019.03.002">a new theory</a> of how, why and when these Malagasy megafauna went extinct.</p>
<h2>Climate at the time of the crash</h2>
<p>The first job is to understand exactly when the megafauna died out.</p>
<p>Radiocarbon dating of <a href="https://doi.org/10.1111/ecog.02376">over 400 recent fossils</a> demonstrates that animals under 22 pounds lived on Madagascar throughout the last 10,000 years. For animals over 22 pounds, there are abundant fossils up to 1,000 years ago, but relatively few since. The biggest decline in number of large animals occurred rapidly between A.D. 700 and 1000 – practically instantaneous given the long history of their existence on the island. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=805&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=805&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=805&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1011&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1011&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265741/original/file-20190326-36267-10yh2bt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1011&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Malagasy graduate student and team member Peterson Faina with stalagmites in a cave in Madagascar.</span>
<span class="attribution"><span class="source">Laurie Godfrey</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>What was the climate doing at that time? One popular theory for the megafaunal extinction has blamed <a href="https://doi.org/10.1111/j.1365-2699.2009.02203.x">island-wide drying</a>. To test this idea, our team has been exploring the caves of Madagascar, collecting and analyzing stalagmites. As stalagmites grow upwards from the cave floor, layer by layer, differences in the chemistry of each layer document changes in the climate outside the cave.</p>
<p>By analyzing chemical composition and comparing ratios of various isotopes in these stalagmites, we created new <a href="https://doi.org/10.1016/j.quascirev.2017.03.017">high-resolution records of changes in the Malagasy ecosystems and climate</a>. We found minor fluctuations in the strength of the summer rains throughout the last 2,000 years, but no significant drying over that period. In fact, A.D. 780-960 was one of the wettest periods of the last 2,000 years. <a href="https://doi.org/10.1111/ecog.02376">Chemical analyses of fossils</a> back up this claim.</p>
<p>So it looks like there was no significant drying around the time the megafauna disappeared.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265742/original/file-20190326-36279-1j4dim6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Many of the forests that originally existed on Madagascar are now replaced by more open, human-modified landscapes, like this palm savanna at Anjohibe.</span>
<span class="attribution"><span class="source">Laurie Godfrey</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Instead, the <a href="https://doi.org/10.1016/j.quascirev.2016.01.007">stalagmite records</a> indicated a rapid and dramatic change in the landscape. Changing ratios of the isotopes carbon-12 to carbon-13 reveal a switch from forests to grassland right around A.D. 900, the same time as the megafaunal population crash. Clearly something big happened around this time.</p>
<h2>Cut marks and evidence of butchery</h2>
<p>With no significant change in the climate, some point to the <a href="https://doi.org/10.1073/pnas.1534700100">arrival of humans</a> on the island as a possible cause of the megafauna population crash. It seems logical that once people arrived on Madagascar, they might have hunted the big animals into extinction. New data suggest that this timing doesn’t add up, though.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=736&fit=crop&dpr=1 600w, https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=736&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=736&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=924&fit=crop&dpr=1 754w, https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=924&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/265925/original/file-20190326-36264-1gtfa8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=924&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of two chop marks on the head of a femur of an extinct lemur, Pachylemur. This individual’s hind limb was removed from the trunk at the hip joint, probably with a machete.</span>
<span class="attribution"><span class="source">Lindsay Meador</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<p><a href="https://doi.org/10.1126/sciadv.aat6925">According to new dates on fossil bones</a> with cut marks on them, humans arrived on Madagascar 10,500 years ago, much earlier than previously believed. But whoever these early people were, there’s no genetic evidence of them left on the island. <a href="https://doi.org/10.1073/pnas.1704906114">New analysis of the human genetic diversity</a> in modern Madagascar suggests the current population derives primarily from two waves of migration: first from Indonesia 3,000 to 2,000 years ago, and later from mainland Africa 1,500 years ago.</p>
<p>So it seems that people lived alongside the megafauna for thousands of years. How did the humans interact with the large animals?</p>
<p>Our new study found dozens of fossils with butchery marks. Cut and chop marks provide compelling evidence as to which species people were hunting and eating. Evidence of butchery of animals that are now extinct continues right up to the time of the megafaunal crash. Some people on Madagascar hunted and ate the megafauna for millennia without a population crash.</p>
<h2>Evidence for a change in land use</h2>
<p>If there was no obvious climate shift and humans lived alongside and sustainably hunted the megafauna for up to 9,000 years, what could have triggered the population crash?</p>
<p>The abrupt land use change might hold some clues. The transition from a forest-dominated ecosystem to a grassland-dominated ecosystem appears to be widespread. Scientists have identified this switch not only in the chemical signature of stalagmites but also in pollen grains buried in layers of <a href="https://doi.org/10.1016/0033-5894(87)90038-X">mud at the bottom of lakes</a>. Ancient lake sediments reveal two other changes occurred at the same time as the shift to grass species: an increase in charcoal from fires and an increase in the fungus <em>Sporormiella</em>, which is associated with the dung of large herbivores <a href="https://doi.org/10.1073/pnas.1534700100">such as cows</a>.</p>
<p>Evidence for simultaneous increases in grassland, fires, and cows and other domesticated animals points to a sudden change in Malagasy lifestyle: the introduction of cattle husbandry and slash-and-burn agriculture known locally as <a href="https://www.madamagazine.com/en/english-tavy-kahlschlag-einer-insel/">Tavy</a>. Here, forests are cut down to make space for rice paddies, and grassland burned to promote the growth of nutritious seedlings for cow fodder.</p>
<p>This move away from foraging and hunting toward farming meant the land could support more people. The result was a rapid rise in the size of the human population – and that’s what we conclude spelled disaster for the megafauna.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266562/original/file-20190329-70982-kfun1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Some Malagasy farmers plow agricultural fields in the traditional way.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/malagasy-farmers-plowing-agricultural-field-traditional-266475566">Damian Ryszawy/Shutterstock.com</a></span>
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<p>Here lies the contradiction of the situation: Hunting megafauna for survival became less important as people could rely on their agriculture and livestock. But cut marks on fossil bones indicate that hunting didn’t altogether stop just because people had other food sources. It turns out that the impact on the megafauna of larger human populations hunting just to supplement their diet was greater than the impact of smaller human populations relying more heavily on the native animals as a vital food source.</p>
<p>Bringing together new data on land use changes, climatic histories, genetics, fossil ages and butchery of the megafauna, we call this change “<a href="https://doi.org/10.1016/j.jhevol.2019.03.002">the subsistence shift hypothesis</a>.” Both the habitat loss and increase in human population arose out of a fundamental change in the way humans lived on Madagascar, from a more nomadic hunter-gatherer lifestyle to an agrarian society. We argue that it was this reorganization on Madagascar around A.D. 700-1000 that led to the crash in the megafaunal population.</p>
<p>Small populations of megafauna lived on in isolated pockets for another few centuries, but their fate was likely already sealed. The majority of the giant birds and animals that were once common across our planet have gone extinct. Many of the remaining giants, such as elephants and rhinos, are threatened or endangered. Will they go the same way as the Malagasy megafauna, casualties of humans’ changing lifestyles?</p><img src="https://counter.theconversation.com/content/112672/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nick Scroxton receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Laurie Godfrey receives funding from the National Science Foundation BCS 1750598. </span></em></p><p class="fine-print"><em><span>Stephen Burns receives funding from the US National Science Foundation (grant AGS‐1702891/1702691).</span></em></p>A series of new studies sheds light on the population crash and extinction of the giant birds, lemurs and more that roamed the island until around A.D. 700-1000.Nick Scroxton, Postdoctoral Research Scholar in Paleoclimatology, UMass AmherstLaurie Godfrey, Emeritus Professor of Anthropology, UMass AmherstStephen Burns, Professor of Geosciences, UMass AmherstLicensed as Creative Commons – attribution, no derivatives.