tag:theconversation.com,2011:/es/topics/megafauna-1833/articles
Megafauna – The Conversation
2024-02-01T19:04:17Z
tag:theconversation.com,2011:article/221873
2024-02-01T19:04:17Z
2024-02-01T19:04:17Z
Horses, camels and deer get a bad rap for razing plants – but our new research shows they’re no worse than native animals
<p>Large introduced herbivores such as feral horses and camels are often seen as “<a href="https://theconversation.com/double-trouble-as-feral-horse-numbers-gallop-past-25-000-in-the-australian-alps-128852">invasive</a>” species which damage native plants. </p>
<p>My colleagues and I published <a href="http://www.science.org/doi/10.1126/science.adh2616">new research</a> in Science testing this assumption and found it isn’t true. Instead, both native and introduced species of plant-eating megafauna (weighing over 45 kilos) have similar impacts on plants. </p>
<p>The effects of introduced megafauna on plants can drive negative public sentiment towards the species. It’s time to change how we think of these animals. </p>
<h2>Megafauna over millennia</h2>
<p>For the last 35-55 million years, megafauna have shaped Earth’s terrestrial ecosystems. Present-day plant and animal species in Australia evolved on a continent dominated by earth-trampling beasts. They include hoofed horse-like kangaroos, tree-thrashing marsupial tapirs and <a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">migratory</a> two-tonne diprotodons resembling womabts. </p>
<p>Sadly, much of the world’s megafauna went extinct as humans radiated out from Africa. Australia lost all its land megafauna with an average weight over 45kg.</p>
<p>This drove radical changes in Australian ecosystems. Ancient megafauna were uniquely able to eat large volumes of fibrous low-nutrient plants. With them gone, fires may have intensified and once-widespread rainforests shifted to <a href="https://www.science.org/doi/10.1126/science.1214261">fire-prone</a> eucalypt forest. </p>
<p>But now, the <a href="https://theconversation.com/from-feral-camels-to-cocaine-hippos-large-animals-are-rewilding-the-world-83301">megafauna have returned</a> – introduced by humans. </p>
<p>Australia, for instance, now has the world’s only wild herd of dromedary camels, extinct in the wild in their native range. Water buffalo wallow in the Top End, though they’re endangered in their native range. And feral horses, also endangered in their native range, roam the Australian Alps. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="image of water buffalo, elephant, horses" src="https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571738/original/file-20240127-94586-1hcvqb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Would an extraterrestrial ecologist be able to tell which of these megafauna is introduced based on their ecological impacts?</span>
<span class="attribution"><span class="source">Steven dosRemedios/Flickr, Cowboy Dave/Flickr, Geoff Whalan/Flickr, Pär Söderquist/Author provided, Caroline Jones/Flickr, Daniela Hartmann/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>How megafauna affects plants</h2>
<p>Our research set out to evaluate the effects of megafauna on plant abundance and plant diversity. To do this, we reviewed all literature available on the impacts of native and introduced megafauna and extracted all available data comparing the effects of megafauna between an excluded area and a control site. </p>
<p>We found no evidence that introduced, “invasive”, or “feral” megafauna have different impacts on native plants than native megafauna. Nor was there evidence that the effects of introduced megafauna in biologically distinct places such as Australia are different from their effects in their native ranges. </p>
<p>Our study adds to a growing <a href="https://link.springer.com/article/10.1007/s10750-020-04378-9">body of research</a> that has looked for differences between the impacts of native and introduced species and failed to find them.</p>
<p>Yes, there are outliers. Some introduced species have novel effects very different what they do in their native ranges, such as introduced diseases and insect herbivores such as <a href="https://theconversation.com/the-invasive-emerald-ash-borer-has-destroyed-millions-of-trees-scientists-aim-to-control-it-with-tiny-parasitic-wasps-158403">emerald ash borer</a>, those with novel defences such as cane toads, or those introduced to islands. But extrapolating to all introduced species may be unjustified. </p>
<h2>Megafauna traits determine their impact</h2>
<p>We found ecological explanations – rather than whether an animal was native or not – explained the effects of both native and introduced megafauna. </p>
<p>In particular, we found the effects of megafauna were determined by their traits. Larger and less-picky species tended to have more positive effects on plant diversity.</p>
<p>This suggests that studying introduced megafauna simply as wildlife rather than as an ecological problem can help us respond to situations where megafauna — native and introduced — come into conflict with conservation goals. </p>
<p>Let’s say there is high abundance of introduced sambar deer eating rare plants in a national park. A typical response is to start shooting. </p>
<p>But if you look at this as an ecological conflict rather than as an introduced species problem, the real issue might be that dingoes are routinely poisoned in the area. </p>
<p>Dingoes, as the top terrestrial predator, create <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169534719300199?via%3Dihub">landscapes of fear</a>, meaning deer and kangaroos can’t eat their way through everything because they have to watch for predators and often flee. The solution may be to <a href="https://theconversation.com/australia-should-enlist-dingoes-to-control-invasive-species-24807">stop killing dingoes</a>.</p>
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Read more:
<a href="https://theconversation.com/australia-should-enlist-dingoes-to-control-invasive-species-24807">Australia should enlist dingoes to control invasive species</a>
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<h2>The double standard of ‘harm’</h2>
<p>It can be a shock to see the impact of feral pigs, deer, camels and buffalo. They eat plants, trample vegetation, or root around in the ground.</p>
<p>These animals do the same thing in their native ranges, where it is not generally considered a bad thing, ecologically. Elephants tear down trees to eat or to make a path. That’s bad for the tree, but gives other species a chance to grow.</p>
<p>Australia’s extinct megafauna would have also trampled sensitive plants and eaten huge volumes of vegetation. Large animals suppress some species and benefit others. For example, buffalo can actually increase plant diversity by chowing down on dominant plant species.</p>
<p>The debate over native versus introduced species can create a double standard when assessing the harm they cause. This is a <a href="https://doi.org/10.1038/474153a">longstanding blind spot</a> in how we think about and study introduced species. </p>
<p>The world could look quite different if we relax cultural beliefs about “belonging” and nativeness.</p><img src="https://counter.theconversation.com/content/221873/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erick Lundgren receives funding from the Australian Research Council.</span></em></p>
Introduced water buffalo and camels trash native plants – don’t they? Our research shows megafauna herbivores have the same impact wherever they are.
Erick Lundgren, Adjunct Lecturer, Queensland University of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/219961
2023-12-20T00:06:41Z
2023-12-20T00:06:41Z
19-million-year-old fossil jaw bone hints the biggest whales first evolved somewhere unexpected
<figure><img src="https://images.theconversation.com/files/566527/original/file-20231219-15-u7qnu9.jpg?ixlib=rb-1.1.0&rect=68%2C0%2C1773%2C1279&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The baleen whale fossil at Museums Victoria Research Institute.</span> <span class="attribution"><span class="source">Eugene Hyland, Museums Victoria</span></span></figcaption></figure><p>Baleen whales are the titans of the ocean, the largest animals to have ever lived. The record holder is the blue whale (<em>Balaenoptera musculus</em>), which can reach <a href="https://www.worldwildlife.org/stories/meet-the-biggest-animal-in-the-world">lengths of up to 30 metres</a>. That’s longer than a basketball court.</p>
<p>However, throughout their evolutionary history, most baleen whales <a href="https://www.science.org/content/article/why-whales-grew-such-monster-sizes">were relatively much smaller</a>, around five metres in length. While still big compared to most animals, for a baleen whale that’s quite small.</p>
<p>However, new fossil discoveries from the Southern Hemisphere are beginning to disrupt this story. The latest is an unassuming fossil from the banks of the Murray River in South Australia.</p>
<p>Roughly 19 million years old, this fossil is the tip of the lower jaws (or “chin”) of a baleen whale estimated to be around nine metres in length, which makes it the new record holder from its time. This find has been published today in the journal <a href="https://doi.org/10.1098/rspb.2023.2177">Proceedings of the Royal Society B: Biological Sciences</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a whale with a piece of yellow bone superimposed on its lower jaw" src="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?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 roughly 19-million-year-old fossil ‘chin’ bone superimposed on a Murray River whale illustration.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<h2>What are baleen whales?</h2>
<p>Most mammals have teeth in their mouth. Baleen whales are a strange exception. While <a href="https://theconversation.com/ancient-whales-had-more-bite-than-todays-gentle-giants-82907">their ancestors had teeth</a>, today’s baleen whales instead have baleen – a large rack of fine, hair-like keratin used to filter out small krill from the water.</p>
<p>This structure enabled baleen whales to feed efficiently on <a href="https://www.scientificamerican.com/article/why-are-blue-whales-so-gigantic/">enormous shoals of tiny zooplankton</a> in productive parts of the ocean, which facilitated the evolution of larger and larger body sizes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a large dark humpback whale with its mouth open, showing off what looks like a solid filter at the top of its mouth" src="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&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 bristle-like baleen, as shown on a humpback whale.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<h2>The ‘missing years’ of whale evolution</h2>
<p>Various groups of <a href="https://www.telegraph.co.uk/news/2023/08/02/whale-heaviest-animal-ever-lived-perucetus-colossus/">toothed whales</a> terrorised the ocean for millions of years, including some that were the <a href="https://theconversation.com/ancient-ancestors-of-modern-baleen-whales-were-toothy-not-so-gentle-giants-96338">ancestors of the toothless baleen whales</a>. Yet at some time between 23 and 18 million years ago these ancient “toothed baleen whales” went extinct.</p>
<p>We aren’t exactly sure when, as fossil whales from this episode in Earth’s history <a href="https://museumsvictoria.com.au/media-releases/mystery-of-whale-fossil-dark-age-solved-in-new-palaeontology-research/">are exceedingly rare</a>. What we do know is immediately after this gap in the whale fossil record, only the relatively small, toothless ancestors of baleen whales remained. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark silhouette of a whale next to a smaller figure of a whale and even smaller human figure" src="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?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 newly described extinct Murray River whale (9 metres) next to a fin whale (26 metres) and a human diver (2 metres).</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan, graphic by Rob French</span></span>
</figcaption>
</figure>
<p>Scientists previously thought baleen whales kept to relatively small proportions until the ice ages (which began from about 3–2.5 million years ago). But the majority of research on trends in the evolutionary history of whales is based on the reasonably well-explored fossil record from the Northern Hemisphere – a notable bias that likely shaped these theories.</p>
<p>Crucially, new fossil finds from the Southern Hemisphere are starting to show us that at least down south, whales got bigger much earlier than previous theories suggest.</p>
<h2>An unexpected find</h2>
<p>More than 100 years ago, palaeontologist Francis Cudmore found the very tips of a large pair of fossil whale jaws eroding out of the banks of the Murray River in South Australia. These 19-million-year-old fossils made their way to Museums Victoria and remained unrecognised in the collection until they were rediscovered in a drawer by one of the authors, Erich Fitzgerald.</p>
<p>Using equations derived from measurements of modern-day baleen whales, we predicted the whale this fossilised “chin” came from was approximately nine metres long. The previous record holder from this early period of whale evolution was only six metres long.</p>
<p>Together with <a href="https://www.nationalgeographic.co.uk/animals/2019/05/fossil-of-85-foot-blue-whale-is-largest-ever-discovered">other fossils</a> from Peru in South America, this suggests larger baleen whales may have emerged much earlier in their evolutionary history and the large body size of whales evolved gradually over many more millions of years than previous research suggested.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's reconstruction of the extinct whale, showing where the fossil is located, and a map of Australia showing the location it was found" src="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&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 fossilised baleen whale ‘chin’ was found along the banks of the Murray River in South Australia.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan, photo by Eugene Hyland</span></span>
</figcaption>
</figure>
<h2>The Southern Hemisphere as the cradle of gigantic whale evolution</h2>
<p>The large whale fossils from Australasia and South America seem to suggest that for most of the evolutionary history of baleen whales, whenever a large baleen whale shows up in the fossil record, it is in the Southern Hemisphere.</p>
<p>Strikingly, this pattern persists despite the fact the Southern Hemisphere contains less than 20% of the known fossil record of baleen whales. While this is an unexpectedly strong signal from our research, it doesn’t come as a complete surprise when we consider living baleen whales.</p>
<p>Today, the temperate seas of the Southern Hemisphere are connected by the chilly Southern Ocean, which surrounds Antarctica and is <a href="https://niwa.co.nz/productivity-of-the-southern-ocean-antarctica">extremely productive</a>, supporting the greatest biomass of marine megafauna on Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph, showing that baleen whales in the Southern Hemisphere were larger than Northern Hemisphere whales throughout most of the last 23 million years" src="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossils from the Southern Hemisphere, including the Murray River whale fossil, are demonstrating that whales may have evolved large body sizes first in the Southern Hemisphere.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<p>Around the time baleen whales started evolving from big to gigantic, the strength of the Antarctic Circumpolar Current was intensifying, eventually leading to the present day powerhouse Southern Ocean. </p>
<p>Today, baleen whales are ecosystem engineers, their huge bodies consuming tremendous amounts of energy. <a href="https://oceanservice.noaa.gov/facts/whale-fall.html">Upon death</a>, these whales provide an abundance of nutrients to deep-sea ecosystems.</p>
<p>As we learn more about the evolutionary history of whales, such as when and where their large size evolved, we can begin to understand just how ancient their role in the ocean ecosystem may have been and how it could shift in tune with global climate change.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-true-origins-of-the-worlds-smallest-and-weirdest-whale-208279">The true origins of the world's smallest and weirdest whale</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/219961/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Patrick Rule currently receives funding from an Engineering and Physical Sciences Research Council UKRI Fellowship, and previously received funding from an Australian Research Council Discovery Project.</span></em></p><p class="fine-print"><em><span>Erich Fitzgerald received funding from an Australian Research Council Linkage Project that supported part of this research.</span></em></p>
A newly described fossil from South Australia is making waves in our understanding of where and when whales evolved titanic body sizes.
James Patrick Rule, Research Affiliate, Monash University
Erich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria Research Institute
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/211712
2023-08-17T19:42:11Z
2023-08-17T19:42:11Z
A 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 Angeles
Lisa N. Martinez, Ph.D. Candidate in Geography, University of California, Los Angeles
Regan E. Dunn, Adjunct Professor of Earth Sciences, USC Dornsife College of Letters, Arts and Sciences
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205556
2023-06-14T12:35:28Z
2023-06-14T12:35:28Z
Forensic evidence suggests Paleo-Americans hunted mastodons, mammoths and other megafauna in eastern North America 13,000 years ago
<figure><img src="https://images.theconversation.com/files/528316/original/file-20230525-21-no8djo.jpg?ixlib=rb-1.1.0&rect=556%2C160%2C3570%2C2456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Animals that shared the landscape with humans disappeared as the ice age ended.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Ice_age_fauna_of_northern_Spain_-_Mauricio_Antón.jpg">Mauricio Antón/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The earliest people who lived in North America shared the landscape with huge animals. On any day these hunter-gatherers might encounter a giant, snarling saber-toothed cat ready to pounce, or a group of elephantlike mammoths stripping tree branches. Maybe a herd of giant bison would stampede past.</p>
<p>Obviously, you can’t see any of these ice age megafauna now. They’ve all been extinct for about 12,800 years. Mammoths, mastodons, huge bison, horses, camels, very large ground sloths and giant short-faced bears all died out as the huge continental ice sheets disappeared at the end of the ice age. What happened to them?</p>
<p>Scientists have pointed to various potential causes for the extinctions. Some suggest <a href="https://doi.org/10.1038/s41467-021-21201-8">environmental changes happened faster</a> than the animals could adapt to them. Others posit a <a href="https://doi.org/10.1073/pnas.0706977104">catastrophic impact of a fragmented comet</a>. Maybe it was <a href="https://doi.org/10.1073/pnas.0501947102">overhunting on the part of humans</a>, or <a href="https://doi.org/10.1146/annurev.ecolsys.34.011802.132415">some combination of all these factors</a>.</p>
<p><a href="https://sc.edu/study/colleges_schools/artsandsciences/sc_institute_archeology_and_anthropology/faculty-staff/moore_christopher.php">One of my major interests as an archaeologist</a> has been to understand how the earliest Paleo-Americans lived and interacted with megafauna species. Just how implicated should humans be in the extinction of these ice age animals? In a new study, my colleagues and I used a forensic technique more commonly used to identify blood on objects at crime scenes <a href="https://doi.org/10.1038/s41598-023-36617-z">to investigate this question</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Artist's rendition of Paleoamerican Clovis encampment with people sitting around campfire under night sky" src="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clovis hunter-gatherers lived in small, mobile groups, likely following animal migrations over long distances.</span>
<span class="attribution"><span class="source">Martin Pate/Southeast Archeological Center, National Park Service</span></span>
</figcaption>
</figure>
<h2>Testing stone tools like murder weapons</h2>
<p>Archaeologists have uncovered a sparse scattering of stone tools left at the campsites of Paleo-American Clovis hunter-gatherers who lived around the time of the megafauna extinctions. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="line drawing of two stone points" src="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=682&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=682&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=682&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=857&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=857&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=857&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Early Paleo-American Clovis points (left) and Middle Paleo-American redstone points (right) have a distinct fluted shape, highlighted in yellow, likely designed to facilitate hafting onto a spear or knife handle for use in hunting and butchery.</span>
<span class="attribution"><span class="source">Darby Erd</span></span>
</figcaption>
</figure>
<p>These include iconic <a href="https://www.britannica.com/topic/Clovis-complex">Clovis spearpoints</a> with their distinctive flutes – concave areas left behind by removed stone flakes that extend from the base to the middle of the point. People most likely made the points this way so they could easily affix them to a spear shaft.</p>
<p>Based on <a href="https://www.heritagedaily.com/2016/02/an-afternoon-walk-and-a-mammoth-find-second-clovis-people-kill-site-found-in-new-mexico/109750">sites excavated in the western United States</a>, archaeologists know Paleo-American Clovis hunter-gatherers who lived around the time of the extinctions at least occasionally killed or scavenged ice age megafauna such as mammoths. There they’ve found preserved bones of megafauna together with the stone tools used for killing and butchering these animals. These sites are crucial for understanding the possible role that early Paleo-Americans played in the extinction event.</p>
<p>Unfortunately, many areas in the Southeastern United States lack sites with preserved bone and associated stone tools that might indicate whether megafauna were hunted there by Clovis or other Paleo-American cultures. Without evidence of preserved bones of megafauna, archaeologists have to find other ways to examine this question.</p>
<p>Forensic scientists have used an <a href="https://www.ojp.gov/ncjrs/virtual-library/abstracts/use-crossover-immunoelectrophoresis-detect-human-blood-protein-soil">immunological blood residue analysis</a> technique called <a href="https://doi.org/10.1016/0379-0738(78)90025-7">immunoelectrophoresis</a> for over 50 years to identify blood residue sticking to objects found at crime scenes. In recent years, researchers have applied this method to identify <a href="https://doi.org/10.1016/j.jasrep.2022.103785">animal blood proteins preserved within ancient stone tools</a>. They compare aspects of the ancient blood with blood antigens derived from modern relatives of extinct animals.</p>
<p>Residue analysis does not rely on the presence of nuclear DNA, but rather on preserved, identifiable proteins that sometimes survive <a href="https://doi.org/10.1006/jasc.2000.0628">within the microscopic fractures and flaws of stone tools</a> created during their manufacture and use. Typically, only a small percentage of artifacts produce <a href="https://library-archives.canada.ca/eng/services/services-libraries/theses/Pages/item.aspx?idNumber=27681369">positive blood residue results</a>, indicating a match between the ancient residue and antiserum molecules from modern animals.</p>
<p><a href="https://www.postandcourier.com/aikenstandard/news/a-lot-of-unknowns/article_95d93585-8455-5af6-b9e1-536b629f49ee.html">A previous blood residue study</a> of a small number of Paleo-American artifacts in South Carolina and Georgia failed to provide evidence that these people had hunted or scavenged extinct megafauna. The researchers found evidence of bison and other animals such as deer, bear and rabbit, but no evidence of Proboscidean (mammoth or mastodon) or of an extinct species of North American horse.</p>
<h2>Identifying ancient prey of human hunters</h2>
<p>My colleagues and I realized we needed a much larger sample of Paleo-American stone tools for testing. Since Clovis points and other Paleo-American artifacts are rare, I relied heavily on local museums, private collectors, collections housed at state universities and even military installations to amass a sample of 120 Paleo-American stone tools from all over North Carolina and South Carolina.</p>
<p>Because these artifacts are irreplaceable, I personally carried all 120 Clovis spearpoints and tools inside a protective case on a flight from South Carolina to the blood residue lab in Portland, Oregon. I coordinated in advance with the Transportation Security Administration so my collection of 13,000-year-old weaponry would make it through the screening process.</p>
<p>The blood residue analysis provided unambiguous proof that the tools had had contact with ancient animal blood proteins. The results included the first direct evidence on ancient stone tools of the blood of extinct mammoth or mastodon (Proboscidean) and the extinct North American horse (Equidae) on Paleo-American artifacts in eastern North America. This evidence is significant because it proves that these animals were present in the Carolinas, and they were hunted or scavenged by early Paleo-Americans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="artist's rendition of prehistoric people hitting a mastodon with spears" src="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&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 likely would have taken a group of hunters to take down a mastodon.</span>
<span class="attribution"><a class="source" href="https://georgiainfo.galileo.usg.edu/gastudiesimages/Mastodon%20Hunt%201.htm">Ed Jackson</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>In addition to Proboscidean and horse, bison (Bovidae) blood residues were most common, adding to earlier blood residue research <a href="https://doi.org/10.7183/0002-7316.81.1.132">suggesting a focus on bison hunting</a> by Clovis and other Paleo-American cultures. Bison in North America did not go extinct but <a href="https://en.wikipedia.org/wiki/Bison_antiquus">instead became smaller</a>, most likely as a result of climate change as the last ice age ended and the climate warmed.</p>
<p>So, what do these results suggest for the extinction debate? While this study does not prove humans were responsible for the extinctions, it does show that early Paleo-Americans across the continent likely hunted or scavenged these animals, at least occasionally. The results also indicate that Proboscideans and horses were around when Clovis people were here – only a few hundred years before their eventual extinction in North America.</p>
<p>Another interesting finding is that while Proboscidean blood residues are found on Clovis artifacts, blood residues for horses (Equidae) are found on both Clovis and Paleo-American points that are slightly more recent younger than Clovis. This may suggest the extinction of Proboscidean was complete in the Carolinas by the end of the Clovis period, and the extinction of ice age horse species took longer.</p>
<p>Testing an even larger sample of Paleo-American stone tools from different regions of North America could help pin down the timing and geographic variability in the extinction of megafauna species and provide more clues about why these animals disappeared when they did.</p><img src="https://counter.theconversation.com/content/205556/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher R. Moore is affiliated with the the non-profit Comet Research Group (CRG).</span></em></p>
A forensic technique more often used at modern crime scenes identified blood residue from large extinct animals on spearpoints and stone tools used by people who lived in the Carolinas millennia ago.
Christopher R. Moore, Research Professor and Director of the Southeastern Paleoamerican Survey (SEPAS) at the South Carolina Institute for Archaeology and Anthropology, University of South Carolina
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/206492
2023-05-30T23:01:55Z
2023-05-30T23:01:55Z
Newly described enormous marsupial wandered great distances across Australia 3.5 million years ago
<figure><img src="https://images.theconversation.com/files/529010/original/file-20230530-25-p0dr9l.JPG?ixlib=rb-1.1.0&rect=440%2C579%2C2160%2C1342&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jacob van Zoelen</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Today, 80% of Australia is arid, but it was not always that way. In the early Pliocene, 5.4 to 3.6 million years ago, Australia had a greenhouse climate, widespread forests and diverse marsupial animals.</p>
<p>As the climate dried out in the late Pliocene, open woodland, grassland and shrubland spread across Australia. How did large marsupials cope with these changes?</p>
<p>In 2017, Flinders University researchers uncovered a skeleton eroding from a cliff face on the Warburton River, at the Australian Wildlife Conservancy’s Kalamurina Station in northern South Australia.</p>
<p>The skeleton belongs to a species in the family <a href="https://en.wikipedia.org/wiki/Diprotodontidae">Diprotodontidae</a> – a group of four-legged herbivores that were the largest marsupials to ever exist. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a rust coloured rock face and a map of Australia above it" src="https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1005&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1005&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1005&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1263&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1263&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528789/original/file-20230529-29-wug34x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1263&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of fossil deposits where the species was found (A & B). Close up of the Main Body of the Tirari Formation as exposed at Keekalanna East with some elements in situ (C).</span>
<span class="attribution"><span class="source">Aaron Camens</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In a new study <a href="https://dx.doi.org/10.1098/rsos.230211">published in Royal Society Open Science today</a>, we describe this fossil finding in detail, providing new insights into how the animal lived and moved.</p>
<h2>Exceptional preservation</h2>
<p>Wombats are the closest living relatives of diprotodontids, but the two are as distantly related as kangaroos are to possums. As a result, palaeontologists have had a hard time reconstructing these large, long-gone animals, especially since most diprotodontid species have been described mainly from jaws and teeth.</p>
<p>But the common, widespread nature of diprotodontid remains indicates they were an integral part of Australian ecosystems until the last species, including the rhino-sized <em>Diprotodon optatum</em>, became extinct about 40,000 years ago. </p>
<p>It is rare to find multiple bones belonging to a single skeleton in the fossil record. Only a handful of studies have described parts of the limbs of a post-Miocene diprotodontid. As such, the newly described skeleton is of great importance and is even more special, as it is the first to be found with associated soft tissue structures. </p>
<p>We also compared the specimen to more than 2,000 diprotodontid elements from museums across the globe, making this the most comprehensive appraisal of a diprotodontid skeleton to date.</p>
<p>Our comparisons revealed the skeleton belongs to a new genus we named <em>Ambulator</em>, meaning walker or wanderer. We chose this name because the locomotory adaptations of the legs and feet of this quarter-tonne animal would have made it well suited to roaming long distances in search of food and water, especially when compared to earlier relatives.</p>
<p>We 3D-scanned the specimen, and the files are freely available for anyone <a href="https://www.morphosource.org/projects/000497863?locale=en">to download and look at online</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black silhouette of a rhino like animal with bones overlaid in several places" src="https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=327&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=327&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=327&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=411&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=411&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529005/original/file-20230530-23-d5un5v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=411&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reassembled partial skeleton of <em>Ambulator keanei</em>, with a silhouette demonstrating advanced adaptations for its style of walking.</span>
<span class="attribution"><span class="source">Jacob van Zoelen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">Giant marsupials once migrated across an Australian Ice Age landscape</a>
</strong>
</em>
</p>
<hr>
<h2>Walking marsupials</h2>
<p>We don’t often think of walking as a special skill – but when you’re big, any movement can be energetically costly, so efficiency is key. </p>
<p>Most large herbivores today, such as elephants and rhinoceroses, are unguligrade, meaning they walk on the tips of their toes, with their wrists or ankles not touching the ground.</p>
<p>Diprotodontids are what we call <a href="https://www.britannica.com/animal/mammal/Locomotion#ref193762">plantigrade</a>, meaning their heel-bone contacts the ground when they walk – similar to human feet. This stance helps distribute weight and reduces energy loss when walking, but uses more energy for other activities such as running.</p>
<p>Many diprotodontids also have so-called extreme plantigrady in their hands – a wrist bone modified into a secondary heel. This “heeled hand” made early reconstructions of these animals look bizarre and awkward.</p>
<p>Development of the wrist and ankle for weight-bearing meant the digits became essentially functionless and likely did not make contact with the ground while walking. This may be why no finger or toe impressions are observed in the trackways of diprotodontids.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&rect=38%2C72%2C2517%2C1716&q=45&auto=format&w=1000&fit=clip"><img alt="A grey rock with shallow, oddly shaped footprints" src="https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&rect=38%2C72%2C2517%2C1716&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528986/original/file-20230530-24-a8jbqg.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">Hand and foot impression of <em>Diprotodon optatum</em> – with no sign of digits.</span>
<span class="attribution"><span class="source">Aaron Camens</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Climbers, walkers and grabbers</h2>
<p>Diprotodontids have limb-bone shapes that can be grouped into three main types. There are those adapted to tree climbing, such as <a href="https://theconversation.com/fossils-reveal-australias-tree-top-heavyweight-herbivore-10888"><em>Nimbadon lavarackorum</em></a> and <em>Ngapakaldia tedfordi</em>; and those adapted to more efficient locomotion and travelling great distances, such as <em>Diprotodon optatum</em> and <em>Ambulator keanei</em> (we call these “walkers”).</p>
<p>There are also diprotodontids that were terrestrial and probably could not climb. However, unlike the walkers, their forelimbs were not as specialised for walking and were able to perform a range of functions. These were “grabbers” such as <em>Neohelos stirtoni</em>, and likely <em>Kolopsis torus</em> and <em>Plaisiodon centralis</em>.</p>
<p>Walkers do not show up in the fossil record until we get to the Pliocene (3.5 million years ago). In fact, <em>A. keanei</em> is the earliest diprotodontid we know of that had these specialised walking adaptations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing skeleton bones in three orientations" src="https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529022/original/file-20230530-25-d332p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparisons of the left hand of three diprotodontids. From left to right a composite hand of: 8 million-year-old Alcoota diprotodontid, a grabber; 3.5 million-year-old <em>A. keanei</em>, a walker; and 50 thousand-year-old <em>Diprotodon optatum</em>, also a walker.</span>
<span class="attribution"><span class="source">Jacob van Zoelen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>During the Pliocene, when <em>A. keanei</em> was around, there was an increase in grasslands and open habitat as Australia became drier. Diprotodontids likely had to travel much greater distances to obtain enough water and their preferred food, which was the soft leaves of shrubs and trees, not grass.</p>
<p>Animals such as <em>Ambulator</em> may have evolved to traverse great distances more efficiently. This may also have allowed diprotodontids to get bigger and support more weight. This would eventually lead to the evolution of the giant and <a href="https://australian.museum/learn/australia-over-time/extinct-animals/diprotodon-optatum/">relatively well-known 2.7 tonne <em>Diprotodon</em></a>. </p>
<p>Unfortunately, we will never get to see great migrating mobs of diprotodontids. But it’s amazing to know such a thing may have once been commonplace across the continent.</p><img src="https://counter.theconversation.com/content/206492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jacob van Zoelen received funding from by the Australian Government Research Training Program Scholarship (Excellence). Travel to collections was partially funded by the Royal Society of South Australia small grant scheme 2018, the University of California Museum of Paleontology Doris O. and Samuel P. Welles Fund 2019, Flinders University Higher Degree Research International Conference Travel Grant 2019 and the North American Paleontology Conference Student Travel Grant.</span></em></p><p class="fine-print"><em><span>Gavin Prideaux receives funding from the Australian Research Council, Australia Pacific Science Foundation, Hermon Slade Foundation, Australian Geographic and National Geographic.</span></em></p><p class="fine-print"><em><span>Aaron Camens 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>
Having special foot adaptations helped these sizeable animals wander long distances, which meant a better chance to find plentiful food and water.
Jacob van Zoelen, PhD Candidate, Flinders University
Aaron Camens, Lecturer in Palaeontology, Flinders University
Gavin Prideaux, Professor, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/203689
2023-05-02T14:05:28Z
2023-05-02T14:05:28Z
From enormous elephants to tiny shrews: how mammals shape and are shaped by Africa’s landscapes
<figure><img src="https://images.theconversation.com/files/521021/original/file-20230414-26-p86mwp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The African elephant is the world’s largest terrestrial mammal.</span> <span class="attribution"><span class="source">Ara Monadjem</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Africa is the world’s most diverse continent for large mammals such as antelopes, zebras and elephants. The heaviest of these large mammals top the scales at over one ton, and are referred to as <a href="https://www.sciencedirect.com/science/article/pii/S2351989416300804?via%3Dihub">megafauna</a>. In fact, it’s the only continent that has not seen a mass extinction of these megafauna.</p>
<p>The continent’s megafauna community includes the world’s largest terrestrial mammal, the <a href="https://www.worldwildlife.org/species/african-elephant">African elephant</a>. Adult African bush elephants can weigh as much as 6 tons. Other giants across African continent include hippopotamuses, rhinoceroses and giraffes.</p>
<p>So, it is only in Africa that ecological interactions and dynamics can be studied as they would have been before the sudden and profound flourishing of <em>Homo sapiens</em> over the past 12 000 years; before then, megafauna would have dominated all terrestrial landscapes on all continents. A visit to Africa is, in other words, a visit to our planet’s past.</p>
<p>In my latest book, <a href="https://witspress.co.za/page/detail/African-Ark/?K=9781776147809">African Ark: Mammals, Landscape and the Ecology of a Continent</a>, I tell the story of how Africa’s mammal fauna arose. </p>
<p>It’s not just a tale of megafauna and other well-known large mammals. I pay particular attention to small mammals, such as mice, bats and shrews. That’s partly because I have been <a href="https://www.researchgate.net/profile/Ara-Monadjem">studying these creatures</a> for the past three decades.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1133&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1133&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1133&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"></span>
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<p>These animals are also generally overlooked by both scientists and the public. But without them, and the ways in which they’ve interacted with each other and with their larger cousins over tens of thousands years, Africa wouldn’t have the richly varied landscapes it does today.</p>
<p>Africa’s mammals are a global treasure that must be protected. However, the lives of local communities are inextricably linked with these mammals and the remaining natural landscapes that harbour their dwindling populations; conservation solutions will require these communities’ active participation and blessing.</p>
<p>In some areas, nature-based tourism may be a viable solution. However, much of the rest of the continent – where no tourists go – will require other, perhaps novel, approaches. What we cannot afford is the extinction of any of these beautiful creatures or the continued loss and reduction of the ecosystem services that they freely provide.</p>
<h2>Early mammal history</h2>
<p>The history of African mammals begins with an apparently unrelated group of creatures. They’re so dissimilar from each other today that taxonomists didn’t work out their true relationships until about two decades ago. These are the elephants, manatees, elephant shrews, African golden moles, hyraxes and tenrecs. Collectively they make up the super-order <em><a href="https://afrotheria.net/">Afrotheria</a></em>. </p>
<p>Today, this group accounts for only a small fraction of the mammal species on the continent. But that is only because Africa – which formed part of the prehistoric southern supercontinent of <a href="https://www.britannica.com/place/Gondwana-supercontinent">Gondwana</a> – was colonised, in stages and over millions of years, by ‘invaders’ from the northern supercontinent of <a href="https://www.britannica.com/place/Laurasia">Laurasia</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/large-mammals-shaped-the-evolution-of-humans-heres-why-it-happened-in-africa-196398">Large mammals shaped the evolution of humans: here’s why it happened in Africa</a>
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</em>
</p>
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<p>These colonists include nearly all the mammals that we normally associate with Africa, including rhinoceroses, zebras, antelopes, primates, bats and even rodents. In return, some Afrotherians, including elephants, roamed out of Africa to colonise other lands further north. </p>
<p>Other mammals, including monkeys and <a href="https://onlinelibrary.wiley.com/doi/10.1002/9781118846506.ch1">caviomorph rodents</a> (such as guinea pigs and capybaras), used Africa as a stepping stone to colonise South America, as did lemurs to colonise Madagascar.</p>
<h2>Shaped by geography</h2>
<p>The variables of physical geography have worked hand in hand with the tectonic forces of prehistory. </p>
<p>Africa is not a uniform landscape that enjoys the same climate and habitat throughout. Some parts, such as Madagascar, are not even connected to the mainland but appear as offshore islands. Terrestrial mammals typically reach islands in two ways: they either raft across the intervening sea, or cross by foot during periods of drier weather or lower sea levels that connect the islands to the mainland. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/kenyan-fossil-shows-chameleons-may-have-rafted-from-mainland-africa-to-madagascar-130814">Kenyan fossil shows chameleons may have 'rafted' from mainland Africa to Madagascar</a>
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<p>In the continent’s interior, other formidable barriers restrict and determine mammal movement. Long, deep, fast-flowing rivers, such as the Congo in central Africa, can be almost as effective a barrier as open oceans. Mountain ranges can form inland ‘islands’ that are as ecologically isolated as their ocean equivalents. </p>
<p>By providing barriers, geographical features limit the movement of animals across the landscape, thereby affecting the composition of mammal communities in different parts of the continent.</p>
<h2>Population shifts</h2>
<p>Another element that’s crucial to telling the story of Africa’s mammals is an understanding of how species and population groups are formed and fluctuate over time. </p>
<p>For example, megafauna play important roles in shaping the landscape and its plant communities. This in turn shapes many smaller animals’ habitats. Hippopotamuses in the Okavango Delta <a href="https://www.researchgate.net/figure/Components-of-the-Okavango-ecosystem-a-Hippo-trail-through-flooded-vegetation-in_fig1_247844833#:%7E:text=In%20the%20panhandle%20and%20permanent,channels%20usually%20lead%20to%20lagoons.">create and maintain open water channels</a>, which serve as critical habitat for fishes. And, by defecating in water, hippos also introduce vast amounts of organic fertiliser into this aquatic ecosystem, helping to enrich it.</p>
<p>Smaller animals, too, shape landscapes. </p>
<p>Some species of rats and mice, such as pouched mice in the genus <em>Saccostomus</em>, are granivores that feed on seeds, including those of trees responsible for bush encroachment in savannas such as the sicklebush. Colleagues and I have <a href="https://www.frontiersin.org/articles/10.3389/fevo.2021.676572/full">shown experimentally</a> that various species of mice in Eswatini actually prefer the seeds of this encroaching plant and hence can assist in controlling its spread. But these rodents require good grass cover for persistence, and hence can’t provide this ecological service in over-grazed, degraded landscapes.</p>
<p>The numbers of animals naturally fluctuate over time, typically reflecting fluctuations in food supply brought about by, for example, droughts or floods. A key determinant of these population fluctuations is also the inherent life history characteristics of a species: short-lived, fast reproducing species such as rats and mice will, by definition, experience greater fluctuations in their numbers than long-lived, slow reproducing species like elephants.</p>
<h2>Conservation</h2>
<p>My book concludes by looking at human interactions with African mammals and the need to conserve these mammals, both for their own sake and for ours. The ecosystem services provided by many mammals are crucial to a healthy environment for all species. Humans evolved in Africa and have interacted with other African mammals for millions of years here. </p>
<p>This is not true on other continents, where humans are – in geological timescales – a recent addition. It may well be that this long relationship between humans and other African mammals is the reason why, despite the losses wrought by humankind, so many large mammals persist on the continent: they have ‘learnt’ through natural selection how to survive with us.</p>
<p><em>The book was written in conjunction with wildlife journalist Mike Unwin and is published by <a href="https://witspress.co.za/page/detail/African-Ark/?K=9781776147809">Wits University Press</a>.</em></p><img src="https://counter.theconversation.com/content/203689/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ara Monadjem receives funding from Oppenheimer Generations. </span></em></p>
Africa’s mammals are a global treasure that must be protected.
Ara Monadjem, Full Professor in the Department of Biological Sciences, University of Eswatini
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/176952
2023-01-24T06:16:06Z
2023-01-24T06:16:06Z
How we cracked the mystery of Australia’s prehistoric giant eggs
<figure><img src="https://images.theconversation.com/files/505414/original/file-20230119-20-rbmop2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1488%2C927&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The giant bird Genyornis went extinct in Australia around 50,000 years ago.</span> <span class="attribution"><span class="source">Peter Trusler</span>, <span class="license">Author provided</span></span></figcaption></figure><p>It’s a long-running Australian detective story. From the 1980s onwards, researchers found eggshell fragments, and on rare occasions whole eggs, exposed in eroding sand dunes within the country’s arid zone (which covers most of Australia’s landmass).</p>
<p>A proportion of shells matched eggs laid by emus, but the rest belonged to a mystery species. Researchers initially identified the eggshells as belonging to a giant, extinct bird called <em>Genyornis</em>. But more recently, a group of scientists challenged this view.</p>
<p>With the help of artificial intelligence software, our team has now resolved this scientific controversy, showing that <em>Genyornis</em> was indeed the bird that laid these eggs. With colleagues based around the world, we have published the findings in <a href="https://www.pnas.org/doi/full/10.1073/pnas.2109326119">Proceedings of the National Academy of Sciences</a>. </p>
<p><em>Genyornis</em> was a flightless bird between two metres and 2.5 metres tall that once roamed the Australian landmass. The eggshell fragments are an important line of evidence about this extinct creature, so being certain about the identity of the bird that laid them is vital.</p>
<p>Some of the shell fragments are 400,000 years old, while the youngest are about 50,000 years old. <a href="https://www.nature.com/articles/ncomms10496">Previous work</a> showed that some of the youngest eggshells had been burned, but not in the way a wildfire would. Instead, scientific tests point to humans cooking the eggs for food.</p>
<p>The time period where <em>Genyornis</em> shells disappear (50,000 years ago) coincides with what’s thought to be the first arrival of humans in Australia. The discovery therefore raises the possibility that our species contributed to its extinction.</p>
<h2>Narrowing the candidates</h2>
<p>The eggshell fragments were first recognised by Dom Williams, a geologist and vertebrate palaeontologist from Flinders University in Adelaide, in 1981. He made the case that the fragments <a href="https://www.tandfonline.com/doi/abs/10.1080/03115518108565426">came from <em>Genyornis</em></a>, which belonged to a group of extinct creatures known as thunderbirds.</p>
<p>In the 1990s, a team including John Magee, at Australian National University, and Gifford Miller, one of the authors of this article, <a href="https://www.science.org/doi/abs/10.1126/science.283.5399.205">provided firm dates</a> for similar shell fragments collected at thousands of arid zone sites. <em>Genyornis</em> was one of many large animals – known as “megafauna” – that once roamed Australia and vanished at around the same time. The work by Miller, Magee and others pinned a clear date of 50,000 years ago on this extinction event.</p>
<p>The association of the eggshells with <em>Genyornis</em> was widely accepted from the 1980s until recently, when it was <a href="https://www.sciencedirect.com/science/article/pii/S027737911530192X">challenged by a team of scientists</a> from Flinders University in Australia. Based upon the size and structure of the eggshells, they argued for a different parent. Their favoured candidate was <em>Progura</em>, a 10kg extinct relative of modern birds such as the brush turkey and malleefowl. </p>
<p>Living birds belonging to this group - known as megapodes – build earthen mounds to incubate their eggs. <a href="https://theconversation.com/a-case-of-mistaken-identity-for-australias-extinct-big-bird-52856">The scientific debate</a> was fought out in academic journals, with neither side conceding.</p>
<h2>Chasing a solution</h2>
<p>Attempting to find a resolution, scientists who thought the eggs belonged to Genyornis turned to DNA. Despite <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2009.2019">the successful extraction</a> of genetic information from eggs of New Zealand’s extinct Moa bird, state-of-the-art DNA sequencing technology drew a blank in this case. The molecules were too degraded after 50,000 years under the hot Australian sun.</p>
<p>However, proteins – the molecular building blocks of cells – can provide similar information and can last for longer than DNA. In our study, we used a technique called amino acid racemisation to identify the shell fragments with the best-preserved proteins.</p>
<p>As part of the work, our team was able to retrieve partial protein sequences from the Australian eggshells. We then used software called AlphaFold, from the Google-owned AI lab DeepMind, to generate predicted structures for the molecules – the first time this has been done for ancient proteins.</p>
<p>Two of us, Matthew Collins and Beatrice Demarchi, contacted the <a href="https://b10k.genomics.cn">Bird 10,000 Genomes (B10K) Project</a>. This has set itself the ambitious goal of sequencing the genomes of all bird species.</p>
<p>B10K project member Josefin Stiller took the reconstructed protein sequences and <a href="https://unfolded.deepmind.com/stories/unlocking-the-mystery-of-the-demon-duck-of-doom">placed them within a “family tree”</a> showing how proteins differ between bird species. The proteins were complete enough to resolve the position of the mystery eggs within the deep branches of this tree of protein sequences, but not sufficiently diagnostic to uniquely identify what the parent bird was.</p>
<p>However, as <a href="https://www.pnas.org/doi/full/10.1073/pnas.2109326119">detailed in our latest paper</a>, the protein sequences were able to conclusively rule out that the parent was a megapode. As there are no other candidate birds, we concluded – as Williams had first proposed in the 1980s – that the eggshells belonged to <em>Genyornis</em>.</p>
<p>This means we can confidently interpret other evidence locked in the shells with implications for how <em>Genyornis</em> went extinct and why the emus that lived alongside it survived. </p>
<h2>Picky eater</h2>
<p>Isotopes are different forms of chemical elements that can record information about factors such as diet and climate. Carbon isotopes within the eggshell fragments provide information on the birds’ diets and show that <em>Genyornis</em> was a pickier eater than the emu. Oxygen isotopes can be used to track aridity and show that conditions were increasingly dry around the time <em>Genyornis</em> eggshells disappear.</p>
<p>In previous work, Miller and his colleagues <a href="https://www.sciencedirect.com/science/article/abs/pii/S0277379116302815">analysed the same isotopes in emu eggshells</a> across the time window of <em>Genyornis’</em> extinction and found that summer-season grasses abruptly disappear from the birds’ diets. This is consistent with a dramatic reduction in monsoon rains.</p>
<p>These findings suggest that <em>Genyornis</em> was already somewhat vulnerable to a changing environment, but another factor may have proved important to its ultimate fate. </p>
<p>When coupled with the lack of evidence from <em>Genyornis</em> skeletons for direct predation, the burnt eggshells suggest that – as is so common elsewhere in the world – human pressure was likely to have been a factor that finally drove these impressive birds to extinction.</p><img src="https://counter.theconversation.com/content/176952/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew James Collins receives funding from The Danish National Research Foundation. He is affiliated with The University of Copenhagen. </span></em></p><p class="fine-print"><em><span>Beatrice Demarchi receives funding from the Italian Ministry of University and Research </span></em></p><p class="fine-print"><em><span>Gifford Miller receives funding from the US National Science Foundation. </span></em></p>
A puzzle over the identity of an extinct bird that laid eggs across Australia has been solved.
Matthew James Collins, Professor of Palaeoproteomics, University of Cambridge
Beatrice Demarchi, Associate professor, Università di Torino
Gifford Miller, Distinguished Professor of Geological Sciences, University of Colorado Boulder
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196037
2022-12-12T19:03:07Z
2022-12-12T19:03:07Z
For the first time ever, we have a complete skull description of a true fossil giant wombat
<figure><img src="https://images.theconversation.com/files/499905/original/file-20221209-16432-imxwza.jpg?ixlib=rb-1.1.0&rect=0%2C127%2C3848%2C2644&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ramsayia reconstruction (r) next to a modern wombat.</span> <span class="attribution"><span class="source">Eleanor Pease</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The place we call Australia today was in many ways vastly different 80,000 years ago.</p>
<p>Perhaps nowhere is this more evident than in the animals that would have roamed the plains and inhabited the forests of the continent. Huge marsupials ruled the land, including giant kangaroos, giant koalas and giant wombats.</p>
<p>In a study published today in <a href="https://doi.org/10.1002/spp2.1475">Papers in Palaeontology</a>, we describe the <a href="https://www.morphosource.org/projects/000455063">most complete skull</a> of one of these giant wombats, a hitherto poorly known species called <em>Ramsayia magna</em>. This marsupial bore more than a passing resemblance to a giant beaver crossed with a modern hairy-nosed wombat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Drawing of a brown, stumpy animal with dog-like ears and a very large snout" src="https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499413/original/file-20221207-16-c8k11w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&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 <em>Ramsayia magna</em>.</span>
<span class="attribution"><span class="source">Eleanor Pease</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>A wombat impostor and a unique skull</h2>
<p>Among the charismatic megafauna of Australia, perhaps the best known is the giant marsupial <em>Diprotodon</em>, often referred to as the “giant wombat”. </p>
<p>Contrary to what this moniker suggests, however, <em>Diprotodon</em> is not a wombat at all. Rather, it belongs to a family as distinct from wombats as hippos are from pigs, or as we are from monkeys.</p>
<p>Nevertheless, “true” giant wombats are known from Australia – <em>Phascolonus</em>, the largest, <em>Sedophascolomys</em>, the smallest, and finally <em>Ramsayia</em>, the rarest (roughly cow, goat and sheep-sized, respectively). <em>Ramsayia</em> was previously only known from isolated tooth and jaw fragments.</p>
<p>In the caves of Mount Etna just outside Rockhampton in Queensland, we uncovered a fossil that turned out to represent the most complete remains of this animal ever found. Our detailed anatomical study of this remarkable new specimen revealed what the animal looked like, its unique adaptations to grazing, and the evolutionary history of the giant wombats.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dark photograph of a person in yellow shirt crouching next to rocks in a cave with a headlight on" src="https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499412/original/file-20221207-16-gs1utb.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 skull of the giant wombat was found in the caves of Mt Etna, Rockhampton.</span>
<span class="attribution"><span class="source">Julien Louys</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Air pockets in the skull</h2>
<p>One of the first things we noted about <em>Ramsayia</em> was that the back of its skull preserved evidence of air pockets or sinuses not found in modern wombats.</p>
<p>These sinuses develop for two primary reasons. The outside of a mammal’s skull sometimes grows at a different pace to the brain cavity and the bones that directly surround it. While an animal (and its skull) can reach enormous sizes, its brain size may lag behind; a very large animal doesn’t always need a much larger brain than its smaller relatives.</p>
<p>To accommodate a huge skull and moderately sized brain without adding too much weight, sinuses develop – air cavities supported by bony struts. A larger skull with sinuses also provides more surface area for the attachment of larger chewing muscles, letting the animal process much tougher or poorer-quality foods than smaller species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Yellow crumbly-looking bone fragments on a white surface, roughly making out the shape of a skull" src="https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499416/original/file-20221207-3971-29psdd.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">View of the inside of the skull of <em>Ramsayia</em>, showing the development of sinuses in the back of the skull (top right of image) and the distinct ‘premaxillary spine’.</span>
<span class="attribution"><span class="source">(Louys et al., 2022)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Although these sinuses have been found in <a href="https://museumsvictoria.com.au/collections-research/journals/memoirs-of-museum-victoria/volume-74-2016/pages-331-342/">other extinct giant marsupials</a>, this is the first time they’ve been recorded in any wombat species.</p>
<p>They would have given <em>Ramsayia</em> a more rounded head than modern wombats, who have famously flat skulls that may be an adaptation to their underground lifestyle. This could mean <em>Ramsayia</em> did not live in burrows like wombats do today.</p>
<p>Interestingly, cranial material for another giant wombat, <em>Phascolonus</em>, (known for decades but still not studied in detail) suggests the top of its head was “<a href="https://en.wikipedia.org/wiki/Phascolonus#/media/File:Phascolonus.jpg">dished-in</a>”. This would indicate that like modern wombats, <em>Phascolonus</em> did not develop these sinuses and they may be unique to <em>Ramsayia</em>.</p>
<h2>A sizeable snout</h2>
<p>The second major feature we noted was the development of a vertical bony spine where most other marsupials have elongated, horizontal nasal bones.</p>
<p>Called a “premaxillary spine”, it most likely developed to provide structural support for a large fleshy nose: not quite a trunk, but certainly a sizeable nasal appendage. In this regard, as well as in the highly curved shape of its gape (the diastema) and incisors, it closely resembles <em>Diprotodon</em>, as well as giant fossil beavers found in America and Eurasia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A museum exhibit showing a bear-like animal with a fleshy, large nose" src="https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499890/original/file-20221208-12502-ac25om.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diprotodon, often incorrectly called the ‘giant wombat’ showing its large, fleshy nose.</span>
<span class="attribution"><span class="source">Julien Louys</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Using the features preserved in the skull of <em>Ramsayia</em>, we compared it to other wombats and wombat-like creatures, to better understand the evolution of giant wombats.</p>
<p>One interesting finding was that all three giant wombats – <em>Phascolonus</em>, <em>Sedophascolomys</em>, and <em>Ramsayia</em> – are more closely related to each other than they are to other extinct and modern wombats. This indicates that gigantism in wombats evolved only once and early in their evolutionary history.</p>
<p>A trend to gigantism was likely in response to the gradual drying out of the Australian continent that started about 20 million years ago and the need to process poorer quality food such as grasses – harder to ingest than leaves and fruits. </p>
<h2>A mysterious extinction</h2>
<p>To find out the age of the specimen, we used a combination of dating methods known as uranium series and <a href="https://www.spectroscopyeurope.com/component/content/article/3328-dating-fossil-teeth-by-electron-paramagnetic-resonance-how-is-that-possible">electron spin resonance</a>. These techniques allow us to date beyond the radiocarbon dating window of around 50,000 years.</p>
<p>Our results indicate this individual lived approximately 80,000 years ago in the Rockhampton region. We also found traces of this species even farther north, towards the Chillagoe area. This shows <em>Ramsayia</em> inhabited temperate to tropical grasslands of ancient Australia.</p>
<p>What caused its final extinction? <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2002.2130">While some have argued</a> the species was wiped out by the arrival of humans, the truth is we don’t yet have enough data to be able to say.</p>
<p>Our paper provides the first ages for this species, and important insights into what it looked like and how it lived. But many more records will be needed to best determine why this giant wombat is no longer with us today.</p>
<hr>
<p><em>We thank Eleanor Pease and Ian Sobbe who also contributed to this article.</em></p><img src="https://counter.theconversation.com/content/196037/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council and the National Geographic Society. </span></em></p><p class="fine-print"><em><span>Gilbert Price receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Mathieu Duval receives funding from the Spanish State Research Agency (AEI). He works as a Senior Research Fellow for the National Research Centre on Human Evolution (CENIEH), Burgos, Spain. He is also Adjunct Senior Research Fellow at the Australian Research Centre for Human Evolution (ARCHE), Griffith University, Brisbane, Australia.</span></em></p><p class="fine-print"><em><span>Robin Beck receives funding from the UK's National Environmental Research Council.</span></em></p>
80,000 years ago, Australia’s landscape was dominated by much larger versions of today’s marsupials – including enigmatic and enormous wombats.
Julien Louys, Deputy Director, Australian Research Centre for Human Evolution, Griffith University
Gilbert Price, Lecturer in Palaeontology, The University of Queensland
Mathieu Duval, Ramón y Cajal (Senior) Research Fellow, Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)
Robin Beck, Lecturer in Biology, University of Salford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/192895
2022-12-05T13:25:26Z
2022-12-05T13:25:26Z
Weasels, not pandas, should be the poster animal for biodiversity loss
<figure><img src="https://images.theconversation.com/files/498335/original/file-20221130-20-3djrpi.jpg?ixlib=rb-1.1.0&rect=6%2C3%2C2037%2C1348&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A short-tailed weasel in Yellowstone National Park, Wyoming.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/2baqDL7">Jacob W. Frank, NPS/Flickr</a></span></figcaption></figure><p>At the <a href="https://www.unep.org/events/conference/un-biodiversity-conference-cop-15">United Nations biodiversity conference</a> that opens in Montreal on Dec. 7, 2022, nations aim to create a new global framework for transforming humanity’s relationship with nature. The <a href="https://www.cbd.int/conferences/2021-2022">conference logo</a> features a human reaching to embrace a panda – but from an ecological perspective, a weasel or badger would be a more appropriate choice.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic of a girl reaching to embrace a panda" src="https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=925&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=925&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=925&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1162&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1162&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498319/original/file-20221130-8088-3h45m9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1162&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Logo for the COP 15 conference in Montreal, which was delayed from its original 2020 date due to COVID-19.</span>
<span class="attribution"><a class="source" href="https://www.cop15news.com/en/index.htm">Convention on Biological Diversity</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Large mammals with widespread appeal, also known as <a href="https://animals.howstuffworks.com/endangered-species/charismatic-megafauna.htm">charismatic megafauna</a>, often represent the highest achievement in biodiversity protection. As the logic goes, saving the tiger, polar bear, wolf or lion means saving an entire ecosystem, since these species often have large ranges and may sit at the top of food chains.</p>
<p>But research shows that, relatively speaking, many large charismatic species aren’t doing that badly in North America. Wolves are <a href="https://www.nytimes.com/2022/03/11/science/california-wolves-misinformation.html">repopulating California</a>, where their last wild ancestor was killed in 1924. Cougars could become <a href="https://doi.org/10.1016/j.ecolmodel.2015.09.026">reestablished across the Midwest</a> over the next several decades. Black bears have regained much of their range in the <a href="https://www.bearbiology.org/wp-content/uploads/2017/10/Scheick_and_McCown_2014_Ursus.pdf">eastern U.S</a>, to the point where many states have a <a href="https://www.outdoorlife.com/story/hunting/record-black-bear-hunting-harvest/">bear hunting season</a>. Similar stories are playing out across Europe, where even large carnivores like the lynx and wolverine are <a href="http://dx.doi.org/10.1126/science.1257553">recovering</a>. </p>
<p>For small carnivores like weasels, skunks and foxes, it’s a different story. These species and their relatives have equal or greater impacts on the ecosystems they inhabit than larger species like wolves. They even provide benefits for humans by preying on rodents that eat crops and infest our houses. Yet small carnivores are of increasing conservation concern because their populations are declining dramatically in many places.</p>
<h2>Many threats but no single cause</h2>
<p>While small carnivores don’t typically get as much public attention as larger species, conservation biologists have been trying to arrest their decline for decades. </p>
<p>For example, the black-footed ferret, a member of the same family as weasels and minks, has been <a href="https://www.fws.gov/species/black-footed-ferret-mustela-nigripes">on the U.S. endangered species list</a> since the list was created in 1973. As recently as the early 1900s there were thousands of black-footed ferrets across western prairies. Today scientists estimate there are <a href="https://blackfootedferret.org/">fewer than 400 left in the wild</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two ferrets with black feet and eye masks, one peeking out of a pipe" src="https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498333/original/file-20221130-22-dzg6n4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&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 U.S. Fish and Wildlife Service is breeding black-footed ferrets in captivity in northern Colorado. Restoring the endangered ferret is considered a key step in reviving prairie ecosystems.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/oct-29-there-are-48-outdoor-pre-conditioning-pens-that-news-photo/186801918">Kathryn Scott Osler/The Denver Post via Getty Images</a></span>
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</figure>
<p>Recent evidence suggests that even the most common and widespread small carnivores are in decline. A 2005 study estimated that eastern spotted skunks, which are rarely seen today but historically occurred across much of the U.S. east of the Rocky Mountains, had <a href="https://doi.org/10.1017/S1367943005001964">declined in number by 90% over the preceding 50 years</a>. </p>
<p>I led an effort in 2021 to determine the status of the most widespread of small carnivores in North America – <a href="https://doi.org/10.1371/journal.pone.0254387">weasels</a>. We found range-wide decreases dating back to the 1960s that paralleled the decline of spotted skunks. </p>
<p>Scientists have a very poor understanding of what has caused losses of weasels and most other small carnivores. We suspect that many stresses may be involved, including changing farming practices, diseases and new carnivores like house cats, domestic dogs, raccoons and striped skunks that follow human development and outcompete or eat native small carnivores. </p>
<p>What we do know is that North America is not unique. Small carnivores are declining globally at an alarming rate. A 2021 review suggests that over the past couple of decades <a href="https://doi.org/10.1016/j.biocon.2021.109005">over half of all small carnivores have declined in number</a>, and a quarter are at risk of extinction. Proportionally, these are the same levels of decline and endangerment as the better-publicized threats to large carnivores. </p>
<h2>Short-legged ecosystem indicators</h2>
<p>We also know that compared with larger species, small carnivores have shorter lives and use smaller areas. This allows them to respond quickly to even minor fluctuations in temperature, habitat change and food availability. In my <a href="https://scholar.google.com/citations?user=CjwvzoIAAAAJ&hl=en&oi=sra">research over the past 23 years</a>, I have learned that these attributes make small carnivores sensitive indicators of even minor shifts in how well their ecosystems work. </p>
<p>A prime example comes from the Channel Islands off the coast of California, home to the diminutive <a href="https://www.nps.gov/chis/learn/nature/island-fox.htm">island fox</a>, a species found nowhere else on earth. In the late 1990s land and wildlife managers noticed a decline in island foxes, which coincided with the decline of bald eagles and arrival of golden eagles on the islands. Golden eagles preyed on the foxes, as well as on non-native wild pigs. At one point the fox population was reduced to fewer than 100 individuals. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2AVRSGkartg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Saving California’s island foxes required reconstructing an ecosystem that human actions had drastically altered.</span></figcaption>
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<p>Restoring island foxes was a complex initiative that involved reintroducing bald eagles – which prey on fish, not mammals – to the islands to chase off golden eagles; eradicating introduced pigs, which served as food for the golden eagles and altered the vegetation where the foxes sheltered; restoring shrubs and grasses; and breeding foxes in captivity, then releasing them. This effort is one of the most prominent examples of biologists intervening to <a href="https://www.nps.gov/chis/learn/nature/island-fox.htm">reverse a species’ slide toward extinction</a>. </p>
<p>More broadly, the island fox story shows that small carnivores can provide unique insight into the structure of ecosystems, because they are at the centers of <a href="https://www.nature.com/scitable/knowledge/library/food-web-concept-and-applications-84077181/">food webs</a>. Look at the diet of a fox or weasel and you have a great snapshot of <a href="https://doi.org/10.1002/fee.2407">how many species are present in that ecosystem</a>. </p>
<p>Losing small carnivores can change ecosystems. Many small carnivores typically prey on small seed-eating rodents like mice and gophers. This reduces rodent impacts on plants and <a href="https://doi.org/10.1016/j.ecoser.2017.12.006">farm crops</a>. It also helps to reduce the <a href="https://doi.org/10.1016/j.ecoser.2017.12.006">spread of tick-borne diseases</a>, since small rodents can serve as <a href="https://doi.org/10.1186/s13071-020-3902-0">hosts for infected ticks</a>.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Cld5PUMrvno/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>For these reasons, I and other ecologists argue that it makes sense to use small carnivores as <a href="https://doi.org/10.1111/mam.12300">barometers of ecosystem health</a>. This would mean replacing polar bears with weasels as global warming poster animals, and keying in on <a href="https://doi.org/10.1111/btp.12635">ocelots</a> rather than jaguars to understand how rainforest destruction is affecting wildlife. </p>
<p>While lions and polar bears are important, I believe ferrets, weasels and foxes deserve the same kind of protection and are a more precise tool for measuring how ecosystems are responding to a rapidly changing world.</p><img src="https://counter.theconversation.com/content/192895/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Jachowski 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>
Polar bears and wolves may get the glory, but small predators like weasels, foxes and their cousins play outsized ecological roles. And many of these species are declining fast.
David Jachowski, Associate Professor of Wildlife Ecology, Clemson University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/191857
2022-10-17T19:04:43Z
2022-10-17T19:04:43Z
New dates suggest Oceania’s megafauna lived until 25,000 years ago, implying coexistence with people for 40,000 years
<figure><img src="https://images.theconversation.com/files/489728/original/file-20221014-17-p3r3cz.jpeg?ixlib=rb-1.1.0&rect=88%2C29%2C4832%2C3223&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>For most of Australia’s human past sea levels were lower than they are today. Australia’s mainland was connected to Papua New Guinea and Tasmania as part of a larger landmass called “Sahul”. </p>
<p>During the Ice Ages Sahul was home to a unique range of megafauna, which included giant marsupials, birds and reptiles. The extinction of <a href="https://australian.museum/learn/australia-over-time/megafauna/">megafauna</a> in Sahul remains one of the most contested debates in Australian science. </p>
<p>Now, our new paper published in <a href="https://onlinelibrary.wiley.com/doi/10.1002/arco.5274">Archaeology in Oceania</a> provides compelling evidence megafauna may have coexisted with people in the region longer than previously thought – and as recently as about 25,000 years ago.</p>
<p>Our research extends the likely period of overlap between megafauna and people to about 40,000 years. It brings new evidence against the theory that people in Sahul drove the megafauna extinction.</p>
<h2>An enduring scientific debate</h2>
<p>Like other regions during the ice ages (a period known as the Pleistocene) Sahul contained the enigmatic megafauna. The term “megafauna” as it’s used in Australia is generally applied to ancient animals that weighed more than about 45kg.</p>
<p>There is disagreement on how Sahul’s megafauna went extinct. Since 1831 – when eminent anatomist Sir Richard Owen received megafauna fossils from Wellington Cave in New South Wales, and a decade later from the Darling Downs in Queensland – there has been speculation about how Sahul’s megafauna went extinct. </p>
<p>Owen argued humans were responsible. Others, such as Prussian scientist <a href="https://search.informit.org/doi/abs/10.3316/informit.627463751345482?casa_token=a69MrpXhe3IAAAAA:ftLRwNOBpEHX-u5y6jbsqgiJpD566GA2mQGdg8PA701tIrN5W9plxqqzscCyiLx6-fXUXkHV4QN7nccJ">Ludwig Leichhardt</a>, favoured environmental change as the cause, proposing megafauna extinction in the Darling Downs occurred as a result of the draining of swamps due to <a href="https://www.britannica.com/science/tectonics">tectonic</a> uplift.</p>
<p>Today the debate continues along similar lines. Some researchers argue Aboriginal people were responsible for driving all megafauna extinct by <a href="https://epicaustralia.org.au/megafauna-mysteries-plotting-unpredictable-and-complex-extinction-cascades/">42,000 years ago</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-coexisted-with-three-tonne-marsupials-and-lizards-as-long-as-cars-in-ancient-australia-138534">Humans coexisted with three-tonne marsupials and lizards as long as cars in ancient Australia</a>
</strong>
</em>
</p>
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<h2>Decades of work in Sahul</h2>
<p>The most direct approach to understanding what happened to the megafauna involves excavating sites containing their remains, and applying a range of techniques to understand how these sites (and their surroundings) have changed through time. Revisiting old sites with new techniques helps us gather as much data as possible.</p>
<p>The most significant research into understanding megafauna extinction in northernmost Sahul was conducted in the 1970s by archaeologist Mary-Jane Mountain at the Nombe rockshelter in the Papuan Highlands.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Some men stand to the side at the Nombe rockshelter, with parts of the earth on the bottom-left partially excavated." src="https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=906&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=906&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=906&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1138&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1138&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489723/original/file-20221014-14-de5ooc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1138&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 Nombe rockshelter excavation in the 1970s provided some of the most significant estimates for when Sahul’s megafauna went extinct.</span>
<span class="attribution"><span class="source">Barry Shaw</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Mountain’s careful excavation of a site known to have been inhabited by people in the late Pleistocene also uncovered megafauna fossils. </p>
<p>While the fossils themselves couldn’t be dated, the dating of charcoal samples, non-megafauna animal bones and snail shells from adjacent deposits revealed megafauna existed in the area as recently as 19,000 years ago. </p>
<p>However, <a href="https://www.science.org/doi/full/10.1126/science.1060264">a paper</a> published in 2001 argued archaeological sites weren’t ideal for testing megafauna extinctions as they lacked near-complete animal fossils that had been moved by people. </p>
<p>Nombe was removed from the list, along with the original dates for megafauna surviving as recently as 19,000 to 25,000 years ago.</p>
<p>In 2016, another <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/arco.5114?casa_token=qg2zVKAmwNEAAAAA%3AbuuqNJYJjvJ6LFenCYYqBOqPzLcLB79-KWME2rdplVap6x7ps7ifbsdWbid1VIF_perhCVjRRSkp9mcQZg">important paper</a> was published reassessing these dates. This research used a more modern carbon-dating approach called accelerated mass spectrometry (AMS) dating. </p>
<p>This method can date much smaller charcoal particles, and once more led researchers to dates that supported the original estimates revealed through Mountain’s work.</p>
<h2>Redating Nombe</h2>
<p>For our new paper, we decided to further test these estimates using uranium-series (U-series) dating of megafauna fossils. The U-series dating technique has been refined over several decades. It allowed us to directly date megafauna fossils from the Papuan Highlands for the first time.</p>
<p>Our <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/arco.5274">research</a> suggests the fossils date to between 22,000 and 27,000 years ago – which is very close to Mountain’s original estimates and the more recent accelerated mass spectrometry dates.</p>
<p>The U-series dating provides minimum age estimates, which means the fossils <em>could</em> be older. But since our estimates are supported by previous accelerated mass spectrometry dating, collectively the data provide a compelling case for the existence of megafauna in Sahul as recently as 25,000 years ago. </p>
<p>This contradicts the persisting theory these animals were extinct by 42,000 years ago. </p>
<p>Our research also extends the period of overlap between megafauna and people. If the earliest dates for people in Sahul go back 65,000 years, this implies some 40,000 years of overlap.</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>
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<hr>
<p>Adding to this, <a href="https://theconversation.com/aboriginal-australians-co-existed-with-the-megafauna-for-at-least-17-000-years-70589">recent work</a> at the Willandra Lakes in NSW and the Seton Rockshelter at Kangaroo Island also estimates Sahul’s megafauna were alive some 30,000 years ago. </p>
<h2>Was there another ancient human?</h2>
<p>Some argued the arrival of people to Sahul drove <a href="https://bigthink.com/hard-science/giant-australian-creatures-called-megafauna-went-extinct-because-of-humans-not-climate-change/">significant environmental change</a>, to the point that megafauna could no longer survive. </p>
<p>But our analysis of pollen at Nombe reveals high-altitude forests (called montane forests) persisted from at least 26,000 years ago to the end of the Pleistocene 10,000 years ago. The archaeological evidence shows people weren’t that active in the area during this time – which suggests it’s unlikely they drove the megafauna extinction.</p>
<p>Rather, we raise the possibility megafauna may have coexisted with <a href="https://australian.museum/learn/science/human-evolution/hominid-and-hominin-whats-the-difference/">hominins</a> (a group including us, <em>Homo sapiens</em>, and our close ancestors) for much longer than previously thought.</p>
<p>Geneticists have found the mysterious ancient humans called Denisovans were likely present in the Papuan Highlands before <em>Homo sapiens</em> arrived. So they may have been familiar with megafauna further back than 65,000 years ago.</p>
<p>But this idea needs to be further investigated. We don’t have Denisovan fossils from Papua New Guinea. We only have <a href="https://www.sciencedirect.com/science/article/pii/S0092867419302181">genetic data</a> in modern Highland populations to study. </p>
<p>More <a href="https://www.nature.com/articles/d41586-018-05330-7?sf191362228=1">field work</a> will help us understand not only how megafauna went extinct across Sahul, but how they interacted with their surroundings, and how their collapse may have shaped today’s environments.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">Giant marsupials once migrated across an Australian Ice Age landscape</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/191857/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Westaway receives funding from the Australian Research Council. </span></em></p>
Our work provides new evidence against the theory that people living in Sahul drove the megafauna extinction.
Michael Westaway, Australian Research Council Future Fellow, Archaeology, School of Social Science, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/190688
2022-09-26T20:03:09Z
2022-09-26T20:03:09Z
Study finds famous Australian caves are up to 500,000 years older than we thought - and it could help explain a megafauna mystery
<figure><img src="https://images.theconversation.com/files/486454/original/file-20220926-26-wzmem4.jpg?ixlib=rb-1.1.0&rect=130%2C7%2C2429%2C1598&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Steve Bourne, Author provided</span>, <span class="license">Author provided</span></span></figcaption></figure><p>South Australia’s <a href="https://www.naracoortecaves.sa.gov.au/world-heritage/why-are-these-caves-so-special">Naracoorte Caves</a> is one of the world’s best fossil sites, containing a record spanning more than half a million years. Among the remains preserved in layers of sand are the <a href="https://theconversation.com/naracoorte-where-half-a-million-years-of-biodiversity-and-climate-history-are-trapped-in-caves-78603">bones</a> of many iconic Australian megafauna species that became <a href="https://www.nature.com/articles/ncomms10511">extinct</a> between 48,000 and 37,000 years ago.</p>
<p>The reasons for the demise of these megafauna species are intensely debated. But the older the fossils we can find, the better we can understand the species’ evolution and extinction. </p>
<p>To date, determining the precise age of the caves has been difficult. However our research demonstrates, for the first time, how old Naracoorte’s caves really are – and the answer is up to 500,000 years older than previously thought.</p>
<p>Our findings shed new light on the antiquity of this important place. We hope this will aid understanding of how biodiversity responds to a changing climate over time.</p>
<figure class="align-center ">
<img alt="illustration of megafauna running and sitting" src="https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485286/original/file-20220919-24-wboteo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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 extinct Pleistocene megafauna in Australia by Julian Hume. Lower left: enormous short-faced kangaroos. Lower right: <em>Thylacoleo carnifex</em> and <em>Wonambi naracoortensis</em>. Centre left and right: <em>Diprotodon optatum</em> and <em>Zygomaturus trilobus</em>.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>A moment in geologic time</h2>
<p>Caves can be extraordinary time capsules, often preserving the remains of long extinct plants and animals in exquisite detail. The Naracoorte Caves in South Australia is one such example.</p>
<p>The cave complex is South Australia’s only World Heritage site. Among the remarkably diverse and complete fossil record are the remains of iconic megafauna such as:</p>
<ul>
<li><em>Thylacoleo carnifex</em> (marsupial predator)</li>
<li><em>Zygomaturus tribolus</em> (huge herbivore)</li>
<li><em>Wonambi naracoortensis</em> (giant constrictor snake)</li>
<li><em>Procoptodon goliah</em> (browsing sthenurine kangaroo). </li>
</ul>
<p>Palaeontologists have excavated and dated many of these fossil deposits and reconstructed the skeletons of a number of megafauna species.</p>
<p>The caves formed when groundwater percolated through cracks in limestone rocks, dissolving them and forming cavities. They were previously dated at between <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169555X14004620?via%3Dihub">0.8 and 1.1 million years old</a> – an estimate generated by dating a fossil dune ridge that lies over the cave complex.</p>
<p>But the methods used to date the dune ridge were <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1502-3885.2008.00052.x?casa_token=V35G_uz7Z4QAAAAA%3A_6xXw2802oskY-l5TxOwJyq_y-tFdLattENDcMHT9K_AWELvB2HuUqVMYUR2sp28D7B1dde_Bjbw27v2">not</a> <a href="https://linkinghub.elsevier.com/retrieve/pii/B9780444536433000546">entirely</a> suitable for the task. As such, a precise age of the caves had not been obtained, until now.</p>
<p>This intricate work involved in our study has taken five years, but it was worth the wait.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">Did people or climate kill off the megafauna? Actually, it was both</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="fossilised bone in rock" src="https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486423/original/file-20220926-388-res0uz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Layers of flowstones overlying sandy layers with fossil bone material in Specimen Cave, Naracoorte.</span>
<span class="attribution"><span class="source">Jon Woodhead, Author provided</span></span>
</figcaption>
</figure>
<h2>What we did</h2>
<p>The dating method <a href="https://www.nature.com/articles/s43247-022-00538-y">we used</a> involved examining the beautiful calcite formations inside the caves. Collectively, these are called “speleothems” and they include stalagmites, stalactites and flowstones. </p>
<p>When speleothems form, tiny amounts of uranium – a radioactive element – are locked inside them. Over time, uranium slowly decays into the element lead. This occurs at a known, constant rate – which means we can use uranium in speleothems as a natural clock to date them. </p>
<p>Doing so involved extracting uranium and lead from the speleothem in a laboratory. We then measured each element and calculate the sample’s age very precisely.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486379/original/file-20220925-5293-pu8e4v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Whale Bone Cave, one of the oldest caves at Naracoorte.</span>
<span class="attribution"><span class="source">Steve Bourne, Author provided</span></span>
</figcaption>
</figure>
<p>Because speleothems only start to grow once a subterranean cavity is formed and above the groundwater table, the oldest speleothem age reveals the minimum age of the cave itself.</p>
<p>From this, we found the caves began to form at least 1.34 million years ago – making them 250,000 to 500,000 years older than previous estimates.</p>
<p>The second part of our study sought to determine when the caves first opened to the surface, allowing both air and animals in. We did this by examining microscopic particles of charcoal and pollen captured in the calcite formations as they grew. </p>
<p>We found charcoal and pollen first appeared in the caves around 600,000 years ago. This suggests the caves may harbour exciting new vertebrate fossil material up to 600,000 years old – more than 100,000 years older than the oldest known <a href="https://www.sciencedirect.com/science/article/abs/pii/S1871101422000188">fossil deposits</a> at the complex.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/naracoorte-where-half-a-million-years-of-biodiversity-and-climate-history-are-trapped-in-caves-78603">Naracoorte, where half a million years of biodiversity and climate history are trapped in caves</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="woman smiles as she descends into cave" src="https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=483&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=483&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=483&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=607&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=607&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485292/original/file-20220919-24-rz0g00.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=607&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lead author Rieneke Weij descending into a cave at Naracoorte.</span>
<span class="attribution"><span class="source">Liz Reed, Author provided</span></span>
</figcaption>
</figure>
<h2>Why this matters</h2>
<p>There’s heated <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">debate</a> about whether the extinction of Australia’s megafauna was the result of humans or the climate. </p>
<p>A good chronology is key to understanding when and how quickly natural processes occurred over time. Without precise ages, we cannot know the rate of change to landscapes, climate or biodiversity.</p>
<p>So while the Naracoorte Caves formed at least 1.34 million years ago, they did not open to the surface until 600,000 years ago. This sheds new light on the vast separation in time between landforms evolving and fossils accumulating. </p>
<p>Our findings will also help palaeontologists target new excavation sites to find older fossils – hopefully providing valuable further evidence of how our continent’s unique biodiversity has changed.</p>
<p>Our new approach can help to unravel how old fossil deposits at other cave complexes <a href="https://www.sciencedirect.com/science/article/abs/pii/S0277379108001650">in Australia</a> and <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/jqs.3110">around</a> the <a href="https://www.pnas.org/doi/full/10.1073/pnas.0402592101">world</a> where both speleothems and vertebrate fossils are found.</p>
<p>Australia’s richness of plant and animal species faces an uncertain future, due to climate change and other human impacts. Studying important sites such as the Naracoorte Caves helps us understand not just how climate change influenced biodiversity in the past, but what might happen in future.</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>
<img src="https://counter.theconversation.com/content/190688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rieneke Weij receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Jon Woodhead receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Kale Sniderman receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Liz Reed receives funding from the Australian Research Council. </span></em></p>
The findings will help us better understand how biodiversity responds to a changing climate over time.
Rieneke Weij, Postdoctoral researcher in Geochemistry/Palaeoclimatology, University of Cape Town
Jon Woodhead, Professor emeritus, The University of Melbourne
Kale Sniderman, Senior Research Fellow, The University of Melbourne
Liz Reed, Research Fellow, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/185778
2022-06-28T19:58:33Z
2022-06-28T19:58:33Z
This giant kangaroo once roamed New Guinea – descended from an Australian ancestor that migrated millions of years ago
<figure><img src="https://images.theconversation.com/files/471017/original/file-20220627-24-fw6o00.jpg?ixlib=rb-1.1.0&rect=7%2C15%2C5168%2C3430&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Illustration by Peter Schouten</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Long ago, almost up until the end of the last ice age, a peculiar giant kangaroo roamed the mountainous rainforests of New Guinea.</p>
<p>Now, research to be <a href="https://doi.org/10.1080/03721426.2022.2086518">published</a> on Thursday by myself and colleagues suggests this kangaroo was not closely related to modern Australian kangaroos. Rather, it represents a previously unknown type of primitive kangaroo unique to New Guinea.</p>
<h2>The age of megafauna</h2>
<p>Australia used to be home to all manner of giant animals called megafauna, until most of them went extinct about 40,000 years ago. These megafauna lived alongside animals we now consider characteristic of the Australian bush – kangaroos, koalas, crocodiles and the like – but many were larger species of these.</p>
<p>There were giant wombats called <em>Phascolonus</em>, 2.5-metre-tall short-faced kangaroos, and the 3-tonne <em>Diprotodon optatum</em> (the largest marsupial ever).
In fact, some Australian megafaunal species, such as the red kangaroo, emu and cassowary, survive through to the modern day.</p>
<p>The fossil megafauna of New Guinea are considerably less well-studied than those of Australia. But despite being shrouded in mystery, New Guinea’s fossil record has given us hints of fascinating and unusual animals whose evolutionary stories are entwined with Australia’s.</p>
<p>Palaeontologists have done sporadic expeditions and fossil digs in New Guinea, including digs by American and Australian researchers in the 1960s, ’70s and ’80s.</p>
<p>It was during an archaeological excavation in the early 1970s, led by Mary-Jane Mountain, that two jaws of an extinct giant kangaroo were unearthed. A young researcher (now professor) named Tim Flannery called the species <em>Protemnodon nombe</em>.</p>
<p>The fossils Flannery described are about 20,000–50,000 years old. They come from the Nombe Rockshelter, an archaeological and palaeontological site in the mountains of central Papua New Guinea. This site also delivered fossils of another kangaroo and giant four-legged marsupials called diprotodontids.</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>An unexpected discovery</h2>
<p>Flinders University Professor Gavin Prideaux and I recently re-examined the fossils of <em>Protemnodon nombe</em> and found something unexpected. This strange kangaroo was not a species of the genus <em>Protemnodon</em>, which used to live all over Australia, from the Kimberley to Tasmania. It was something a lot more primitive and unknown.</p>
<p>In particular, its unusual molars with curved enamel crests set it apart from all other known kangaroos. We moved the species into a brand new genus unique to New Guinea and (very creatively) renamed it <em>Nombe nombe</em>.</p>
<figure>
<iframe src="https://player.vimeo.com/video/724328370" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">A 3D surface scan of a specimen of <em>Nombe nombe</em>, specifically a fossilised lower jaw from central Papua New Guinea. (Courtesy of Papua New Guinea Museum and Art Gallery, Port Moresby).</span></figcaption>
</figure>
<p>Our findings show <em>Nombe</em> may have evolved from an ancient form of kangaroo that migrated into New Guinea from Australia in the late Miocene epoch, some 5–8 million years ago. </p>
<p>In those days, the islands of New Guinea and Australia were connected by a land bridge due to lower sea levels – whereas today they’re separated by the Torres Strait.</p>
<p>This “bridge” allowed early Australian mammals, including megafauna, to migrate to New Guinea’s rainforests. When the Torres Strait flooded again, these animal populations became disconnected from their Australian relatives and evolved separately to suit their tropical and mountainous New Guinean home. </p>
<p>We now consider <em>Nombe</em> to be the descendant of one of these ancient lineages of kangaroos. The squat, muscular animal lived in a diverse mountainous rainforest with thick undergrowth and a closed canopy. It evolved to eat tough leaves from trees and shrubs, which gave it a thick jawbone and strong chewing muscles. </p>
<p>The species is currently only known from two fossil lower jaws. And much more remains to be discovered. Did <em>Nombe</em> hop like modern kangaroos? Why did it go extinct? </p>
<p>As is typical of palaeontology, one discovery inspires an entire host of new questions.</p>
<h2>Strange but familiar animals</h2>
<p>Little of the endemic animal life of New Guinea is known outside of the island, even though it is very strange and very interesting. Very few Australians have much of an idea of what’s there, just over the strait. </p>
<p>When I went to the Papua New Guinea Museum in Port Moresby early in my PhD, I was thrilled by the animals I encountered. There are several living species of large, long-nosed, worm-eating echidna – one of which weighs up to 15 kilograms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Author Isaac Kerr poses for a photo, holding an Australian giant kangaroo jaw in his left hand" src="https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471027/original/file-20220627-22-91nec3.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">I’m excited to start digging in New Guinea’s rainforests!</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>There are also dwarf cassowaries and many different wallaby, tree kangaroo and possum species that don’t exist in Australia – plus many more in the fossil record.</p>
<p>We tend to think of these animals as being uniquely Australian, but they have other intriguing forms in New Guinea.</p>
<p>As an Australian biologist, it’s both odd and exhilarating to see these “Aussie” animals that have expanded into new and weird forms in another landscape. </p>
<p>Excitingly for me and my colleagues, <em>Nombe nombe</em> may breathe some new life into palaeontology in New Guinea. We’re part of a small group of researchers that was recently awarded a grant to undertake three digs at two different sites in eastern and central Papua New Guinea over the next three years. </p>
<p>Working with the curators of the Papua New Guinea Museum and other biologists, we hope to inspire young local biology students to study palaeontology and discover new fossil species. If we’re lucky, there may even be a complete skeleton of <em>Nombe nombe</em> waiting for us.</p><img src="https://counter.theconversation.com/content/185778/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isaac Alan Robert Kerr receives funding from the Royal Society of South Australia.</span></em></p>
A peculiar giant kangaroo that once lived in New Guinea would have descended from a much more ancient form that migrated from Australia, between 5 million and 8 million years ago.
Dr Isaac A. R. Kerr, PhD Candidate for Palaeontology, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/173745
2021-12-14T19:10:56Z
2021-12-14T19:10:56Z
Fossil find reveals giant prehistoric ‘thunder birds’ were riddled with bone disease
<figure><img src="https://images.theconversation.com/files/437472/original/file-20211214-17-1onlc9e.jpg?ixlib=rb-1.1.0&rect=31%2C7%2C5251%2C3493&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Phoebe McInerney/@phoebyornis</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Until around 45,000 years ago, Australia was home to <em><a href="https://theconversation.com/a-case-of-mistaken-identity-for-australias-extinct-big-bird-52856">Genyornis newtoni</a></em>, a fearsomely huge bird weighing roughly 230kg – almost six times as much as an emu – and standing 2 metres tall.</p>
<p>This giant, from a unique group of Australian flightless birds called the <a href="https://theconversation.com/new-research-reveals-the-origin-of-australias-extinct-flightless-giants-the-mihirung-birds-85394">dromornithids</a> or “thunder birds”, was among the largest birds that have ever lived. And then, along with many of Australia’s other “megafaunal” species, it disappeared, for reasons that still remain debated.</p>
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Read more:
<a href="https://theconversation.com/new-research-reveals-the-origin-of-australias-extinct-flightless-giants-the-mihirung-birds-85394">New research reveals the origin of Australia’s extinct flightless giants, the mihirung birds</a>
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<p>Fossils of <em>Genyornis</em> are mainly found at the famous South Australian fossil site of Lake Callabonna, which was first studied in 1893. This exceptional site preserves hundreds of megafaunal fossils, in the same location and in many cases the same exact body position in which they died after becoming stuck in the muddy lake bed.</p>
<p>New research, published in the journal <a href="https://doi.org/10.1002/spp2.1415">Papers in Palaeontology</a>, shows that getting stuck in the mud was not the birds’ only concern. Bone infections also seem to have been common in this population – highlighting the challenges these birds were facing as their species began to die out.</p>
<h2>The sickness</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=733&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=733&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=733&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=921&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=921&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437476/original/file-20211214-19-10d9f7y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=921&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">Infection on the sternum or chest plate with images of the internal structures associated with the infection.</span>
<span class="attribution"><span class="source">Credit: PL McInerney</span></span>
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<p>As we worked on the fossils in the Flinders University’s palaeontology lab, we noticed several of the bones just didn’t look quite right. They showed unusual distortions, cavities, and a “frothy” surface texture – all clear signs of abnormal bone infections.</p>
<p>We next looked inside the affected bones with the help of CT scans, which confirmed they had suffered abnormal development, distortion and destruction of their internal structure. Investigation into the type of illness that could cause such pathologies led to their diagnosis as osteomyelitis.</p>
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<a href="https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=642&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=642&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=642&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=806&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=806&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437475/original/file-20211214-17-ver0sp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=806&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">Infection on the leg of <em>Genyornis newtoni</em> and a life reconstruction of the injured bird.</span>
<span class="attribution"><span class="source">Credit: PL McInerney</span></span>
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<p>Osteomyelitis is a chronic bacterial infection of bone tissue, which can be caused either by trauma that lets microbes directly enter bone tissue, or via transmission from infected soft tissues nearby. It can cause serious damage.</p>
<p>Of the 34 partial skeletons of <em>Genyornis</em>, four showed signs of bone infections. But the real number is likely higher, because we couldn’t assess all bones from all 34 individuals.</p>
<p>With the chest, leg and foot regions afflicted, individuals would have suffered pain and restricted mobility. As a result, finding enough water and food around the muddy lake beds of Lake Callabonna would have become an arduous task.</p>
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Read more:
<a href="https://theconversation.com/a-case-of-mistaken-identity-for-australias-extinct-big-bird-52856">A case of mistaken identity for Australia's extinct big bird</a>
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<h2>Disease and drought</h2>
<p>These birds seem to have suffered an unusually high rate of bone disease, compared with today’s birds. This suggests the disease was not random, but instead was associated with a particular environmental cause – but what?</p>
<p>One way to help answer this question is to date the fossils accurately, and then to compare their plight with what we know was happening to the environment at Lake Callabonna at the time.</p>
<p>Calculating the age of these intriguing fossils is not necessarily straightforward because, like many of Australia’s extinct megafauna, they are too old for the classic radiocarbon dating method to work.</p>
<p>So we used an alternative dating technique called <a href="https://www.nature.com/articles/s43586-021-00068-5?proof=t">single-grain optically stimulated luminescence</a>, which reveals when sand grains in the surrounding lake sediments were deposited. This provides a useful estimate of when the birds became mired in the mud.</p>
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<a href="https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=730&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=730&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=730&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=917&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=917&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437483/original/file-20211214-23-1pyf0ic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=917&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 dating of the Lake Callabonna sediments.</span>
<span class="attribution"><span class="source">Photos supplied by Lee Arnold</span></span>
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<p>As this dating technique applies to sediments rather than bones, it can also be used to reveal the lake history. In particular, it can distinguish between times when the lake was full of water and was accumulating mud on the lake floor, and times when it was much drier and was accumulating wind-blown sands.</p>
<p>Our study revealed that the beleaguered <em>Genyornis</em> population met its demise getting stuck in sediments laid down between 54,200 and 50,400 years ago. Sediments dated from Lake Callabonna and nearby lake systems reveal that a protracted drought phase began around 50,000-46,000 years ago. After this time, the permanent and extensive water body was transformed into the dry lake bed seen today.</p>
<p>This suggests the birds’ fate was sealed once the lake began to dry up. The population became trapped in the freshly exposed lake floor muds as they searched for ever-diminishing water supplies.</p>
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<img alt="" src="https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437484/original/file-20211214-13-74x2ws.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">
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<span class="caption">Researchers excavating the Lake Callabonna salt lakes.</span>
<span class="attribution"><span class="source">Photo supplied by Phoebe McInerney</span></span>
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<h2>A role in their extinction?</h2>
<p>The rare preservation of <em>Genyornis</em> fossils at Lake Callabonna offers an extraordinary opportunity to investigate the impact of environmental change on this now-extinct population.</p>
<p>When resources are limited, as they would have been during these severe droughts, birds can initiate a stress response that helps them survive until the next time of plenty. But in the long term, this stress response directs resources away from the immune system, ultimately increasing the birds’ susceptibility to infection and disease.</p>
<p>Thus, it is perhaps no surprise the <em>Genyornis</em> bones bear the hallmarks of severe disease.</p>
<p>There is no conclusive evidence that <em>Genyornis</em> survived for long beyond this time. The drying-out of the lakes they called home may have ultimately sealed their extinction fate.</p><img src="https://counter.theconversation.com/content/173745/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phoebe McInerney receives funding from Australian Government Research Training Program Scholarship. </span></em></p><p class="fine-print"><em><span>Lee Arnold receives funding from The Australian Research Council. </span></em></p><p class="fine-print"><em><span>Trevor H. Worthy receives funding from The Australian Research Council. </span></em></p>
Genyornis newtoni was one of the biggest birds ever to walk the earth. And new research shows its mysterious extinction may have come amid a bout of widespread bone disease as its lake home dried out.
Phoebe McInerney, PhD Candidate in Avian Palaeontology, Vertebrate Palaeontology Group, Flinders University
Lee Arnold, Associate Professor in Earth Sciences, Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong
Trevor H. Worthy, Associate Professor, Vertebrate Palaeontology Group, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/160092
2021-05-03T20:07:44Z
2021-05-03T20:07:44Z
Humans weren’t to blame for the extinction of prehistoric island-dwelling animals
<figure><img src="https://images.theconversation.com/files/398315/original/file-20210503-13-puahsf.JPG?ixlib=rb-1.1.0&rect=0%2C317%2C4928%2C2397&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>From the moas of New Zealand to the dodos of Mauritius, humans have hunted many island-dwelling species to extinction in the relatively recent past. But our research reveals humans haven’t always necessarily been agents of ecosystem destruction.</p>
<p>Our study, <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.2023005118">published today in Proceedings of the National Academy of Sciences</a>, shows that until around 12,000 years ago, the arrival of humans on new islands didn’t spell certain doom for the animals that already lived there, and that in most cases their extinction was due to many different factors. </p>
<p>That has since changed, of course. When humans first arrived in New Zealand around the years 1250–1300, they brought with them sophisticated toolkits, advanced maritime technologies, and a few animal companions. They landed in an ecosystem that had never seen any of these things.</p>
<p>Within a few centuries of landing, the biggest animals on these islands, the giant moas, were extinct, and alongside them numerous other birds, reptiles and amphibians. The true extent of these extinctions will probably never be known, but almost certainly runs to more than 30 different species. In other Pacific islands the scenario was much the same. </p>
<p>Further afield, on the Indian Ocean island of Mauritius, the arrival of humans was so inextricably linked to the demise of the dodo that this species has become a global emblem of extinction.</p>
<p>These events, relatively recent in evolutionary terms, have fostered a powerful and enticing narrative: that humans are perennially the agents of destruction and ecological folly. </p>
<h2>The overkill hypothesis</h2>
<p>These episodes of overhunting prompted the US geoscientist Paul Martin to propose his “<a href="https://science.sciencemag.org/content/179/4077/969">overkill hypothesis</a>” to explain extinctions of iconic species at the hands of humans. Martin surmised that when humans arrived in North America, they began hunting the biggest animals they found. Within a few generations, these “megafauna” had been wiped out.</p>
<p>This hypothesis has since been applied around the world. Megafauna extinctions in Africa, Europe, North America, South America and Australia have all been attributed to humans overhunting animals, destroying their habitats, or both.</p>
<p>In a relatively obscure part of the world, however, our earlier research revealed a different story. We work in Nusa Tenggara Timur, a series of small islands found in eastern Indonesia and Timor-Leste and north of Australia. Although these islands have never been connected to the mainland, the earliest records of humans date to about 45,000 years ago. They also hosted various now-extinct species, including stegodons (elephant-like creatures), giant rats, and birds.</p>
<p>As we analysed fossil and archaeological records across several of these islands, it became clear the extinctions here were not caused by human overkill. Some species from Nusa Tenggara Timur, such as the stegodons, disappeared well before modern humans arrived. Others, like the giant rats, lived alongside people for tens of thousands of years, withstanding millennia of hunting and consumption.</p>
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<a href="https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Modern and giant rat skulls." src="https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398316/original/file-20210503-21-111o5ev.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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">Prehistoric giant rats’s skulls (right) were much bigger than those of their modern-day cousins.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>Why were these island extinctions so different from the more famous human-caused examples elsewhere? Perhaps it was the fact that humans arrived relatively early, in smaller numbers, and with less sophisticated hunting tools. Or perhaps it was the nature of the islands themselves.</p>
<p>To try to answer these questions, we mounted a global investigation of the impacts of humans and their evolutionary ancestors on the species that lived on islands. Our study covered a huge span of time known as the Pleistocene: from 2.6 million years ago, when humans’ evolutionary ancestors began spreading across the globe, to 11,700 years ago, shortly before modern humans developed agriculture and new technologies. </p>
<p>This vast period predates the times when most islands in the Pacific and Indian Oceans were first occupied.</p>
<p>We assembled leading archaeologists and palaeontologists who study island ecosystems. Next, we compared notes to see whether the extinctions of animals on each of these islands coincided with the arrival of humans.</p>
<h2>Humans off the hook?</h2>
<p>On only two islands, Cyprus and Kume, were all extinctions coincident with humans’ arrival. Some other extinctions on other islands also coincided with human colonisation. But, broadly speaking, the dominant pattern across all the islands we examined was that there was no relationship between humans arriving, and local animals going extinct.</p>
<p>This was true of both oceanic and continental islands (islands connected to continents during periods of lowered sea levels). In the latter, extinctions mostly happened when the islands were connected to the mainland. In the former, we found that volcanic eruptions weren’t coincident with extinctions either.</p>
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Read more:
<a href="https://theconversation.com/it-was-growing-rainforests-not-humans-that-killed-off-southeast-asias-giant-hyenas-and-other-megafauna-147656">It was growing rainforests, not humans, that killed off Southeast Asia's giant hyenas and other megafauna</a>
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<p>Our study revealed important aspects of the relationship between islands, humans and extinctions. First, no two islands are the same. Each will be impacted differently by people, and in some cases the impacts may not necessarily be detrimental – in fact, they could conceivably even be beneficial. </p>
<p>Second, it was not until the past few millennia that humans began to wreak widespread destruction on island ecosystems. These are a result of overhunting, yes, but probably more from environmental degradation, introduction of invasive species, and overpopulation.</p>
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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>
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<p>Our research shows that even in the most fragile ecosystems — islands — humans have not always been the agents of destruction they are today. We should be wary of projecting recent human behaviours and their negative impacts into the deeper past. And taking a broader view of prehistoric extinctions will help inform our current efforts to save the species that survive today.</p><img src="https://counter.theconversation.com/content/160092/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council and the Wenner-Gren Foundation. </span></em></p><p class="fine-print"><em><span>Sue O'Connor receives funding from the Australian Research Council ARC Centre of Excellence for Australian Biodiversity and Heritage, The Australian National University, ACT. </span></em></p>
The famous deaths of moas and dodos has fed a narrative in which humans are agents of extinction for island-dwelling animals. But research suggests this only recently became the case.
Julien Louys, ARC Future Fellow, Griffith University
Sue O'Connor, Distinguished Professor, School of Culture, History & Language, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/159909
2021-04-29T20:06:33Z
2021-04-29T20:06:33Z
Feral desert donkeys are digging wells, giving water to parched wildlife
<p>In the heart of the world’s deserts – some of the most expansive wild places left on Earth – roam herds of feral donkeys and horses. These are the descendants of a once-essential but now-obsolete labour force. </p>
<p>These wild animals are generally considered <a href="https://nt.gov.au/environment/animals/feral-animals/feral-donkey">a threat to the natural environment</a>, and have been the target of mass eradication and lethal control programs in Australia. However, as we show in a <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.abd6775">new research paper in Science</a>, these animals do something amazing that has long been overlooked: they dig wells — or “ass holes”. </p>
<p>In fact, we found that ass holes in North America — where feral donkeys and horses are widespread — dramatically increased water availability in desert streams, particularly during the height of summer when temperatures reached near 50°C. At some sites, the wells were the only sources of water. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397616/original/file-20210428-21-n4e3f6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=283&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Feral donkeys and horses dig wells to desert groundwater.</span>
<span class="attribution"><span class="source">Erick Lundgren</span></span>
</figcaption>
</figure>
<p>The wells didn’t just provide water for the donkeys and horses, but were also used by more than 57 other species, including numerous birds, other herbivores such as mule deer, and even mountain lions. (The lions are also predators of feral donkeys and <a href="https://www.nytimes.com/2018/05/12/sunday-review/let-mountain-lions-eat-horses.html">horses</a>.) </p>
<p>Incredibly, once the wells dried up some became nurseries for the germination and establishment of wetland trees.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=675&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=675&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=675&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=848&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=848&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397621/original/file-20210428-19-1egzibz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=848&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Numerous species use equid wells. This includes mule deer (top left), scrub jays (middle left), javelina (bottom left), cottonwood trees (top right), and bobcats (bottom right).</span>
<span class="attribution"><span class="source">Erick Lundgren</span></span>
</figcaption>
</figure>
<h2>Ass holes in Australia</h2>
<p>Our research didn’t evaluate the impact of donkey-dug wells in arid Australia. But <a href="https://conbio.onlinelibrary.wiley.com/doi/10.1111/cobi.13447">Australia is home</a> to most of the world’s feral donkeys, and it’s likely their wells support wildlife in similar ways. </p>
<p>Across the Kimberley in Western Australia, helicopter pilots regularly saw strings of wells in dry streambeds. However, these all but disappeared as mass shootings since the late 1970s have driven donkeys <a href="https://www.abc.net.au/news/rural/2020-01-20/cost-benefit-analysis-of-culling-feral-donkeys-in-the-kimberley/11874064">near local extinction</a>. Only on <a href="https://www.kachana-station.com/projects/wild-donkey-project/">Kachana Station</a>, where the last of the Kimberley’s feral donkeys are protected, are these wells still to be found. </p>
<p>In Queensland, <a href="https://www.goodreads.com/book/show/2599093-they-all-ran-wild">brumbies</a> (feral horses) have been observed digging wells deeper than their own height to reach groundwater.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="https://www.kachana-station.com/projects/wild-donkey-project/" src="https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=444&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=444&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=444&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397516/original/file-20210428-21-1y9ate5.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"></a>
<figcaption>
<span class="caption">Some of the last feral donkeys of the Kimberley.</span>
<span class="attribution"><span class="source">Arian Wallach</span></span>
</figcaption>
</figure>
<p>Feral horses and donkeys are not alone in this ability to maintain water availability through well digging. </p>
<p>Other equids — including mountain zebras, Grevy’s zebras and the kulan — dig wells. African and Asian elephants dig wells, too. These wells provide resources for other animal species, including the near-threatened <a href="https://www.goviinkhulan.com/english/our-projects/research/">argali</a> and the <a href="https://books.google.com/books/about/Tracking_Gobi_Grizzlies.html?id=paBHjgEACAAJ">mysterious Gobi desert grizzly bear</a> in Mongolia. </p>
<p>These animals, like most of the world’s remaining megafauna, <a href="https://advances.sciencemag.org/content/1/4/e1400103">are threatened</a> by human hunting and habitat loss.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397627/original/file-20210428-15-7k3eft.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=283&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Other megafauna dig wells, too, including kulans in central Asia, and African elephants.</span>
<span class="attribution"><span class="source">Petra Kaczensky, Richard Ruggiero</span></span>
</figcaption>
</figure>
<h2>Digging wells has ancient origins</h2>
<p>These declines are the modern continuation of an ancient pattern visible since humans left Africa during the late Pleistocene, beginning around 100,000 years ago. As our ancestors stepped foot on new lands, the largest animals <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">disappeared</a>, most likely from human hunting, with contributions from climate change. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">Giant marsupials once migrated across an Australian Ice Age landscape</a>
</strong>
</em>
</p>
<hr>
<p>If their modern relatives dig wells, we presume many of these extinct megafauna may have also dug wells. In Australia, for example, a pair of <a href="https://www.abc.net.au/news/2020-02-07/water-diviner-wombats-bring-animals-to-water-hole/11937990">common wombats</a> were recently documented digging a 4m-deep well, which was used by numerous species, such as wallabies, emus, goannas and various birds, during a severe drought. This means ancient giant wombats (<em>Phascolonus gigas</em>) may have dug wells across the arid interior, too. </p>
<p>Likewise, a diversity of equids and elephant-like proboscideans that once roamed other parts of world, may have dug wells like their surviving relatives. </p>
<p>Indeed, these animals have left riddles in the soils of the Earth, such as the preserved remnants of a 13,500-year-old, 2m-deep well in western North America, perhaps dug by a mammoth during an ancient drought, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169555X1100314X">as a 2012 research paper proposes</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-feral-camels-to-cocaine-hippos-large-animals-are-rewilding-the-world-83301">From feral camels to 'cocaine hippos', large animals are rewilding the world</a>
</strong>
</em>
</p>
<hr>
<h2>Acting like long-lost megafauna</h2>
<p>Feral equids are resurrecting this ancient way of life. While donkeys and horses were introduced to places like Australia, it’s clear they hold some curious resemblances to some of its great lost beasts. </p>
<p><a href="https://www.pnas.org/content/117/14/7871.short">Our previous research published in PNAS</a> showed introduced megafauna actually make Australia overall more functionally similar to the ancient past, prior to widespread human-caused extinctions. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=258&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=258&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=258&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=324&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=324&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397643/original/file-20210428-13-1whsqw6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=324&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Donkeys share many similar traits with extinct giant wombats, who once may have dug wells in Australian drylands.</span>
<span class="attribution"><span class="source">Illustration by Oscar Sanisidro</span></span>
</figcaption>
</figure>
<p>For example, donkeys and feral horses have trait combinations (including diet, body mass, and digestive systems) that mirror those of the giant wombat. This suggests — in addition to potentially restoring well-digging capacities to arid Australia — they may also influence vegetation in similar ways. </p>
<p>Water is a limited resource, made even scarcer by farming, mining, climate change, and other human activities. With deserts predicted to spread, feral animals may provide unexpected gifts of life in drying lands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397696/original/file-20210428-17-ybw0wq.png?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">Feral donkeys, horses (mapped in blue), and other existing megafauna (mapped in red) may restore digging capacities to many drylands. Non-dryland areas are mapped in grey, and the projected expansion of drylands from climate change in yellow.</span>
<span class="attribution"><span class="source">Erick Lundgren/Science</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Despite these ecological benefits in desert environments, feral animals have long been denied the <a href="https://ro.uow.edu.au/asj/vol8/iss2/14/">care</a>, curiosity and <a href="https://theconversation.com/non-native-species-should-count-in-conservation-even-in-australia-127926">respect</a> native species deservedly receive. Instead, these animals are targeted by <a href="https://www.abc.net.au/religion/this-treatment-of-donkeys-makes-brutes-out-of-us/10101372">culling</a> programs for conservation and the meat industry. </p>
<p>However, there are signs of change. New fields such as <a href="https://www.uts.edu.au/research-and-teaching/our-research/centre-compassionate-conservation">compassionate conservation</a> and <a href="https://www.sydney.edu.au/arts/our-research/futurefix/multispecies-justice.html">multispecies justice</a> are expanding conservation’s <a href="https://conbio.onlinelibrary.wiley.com/doi/abs/10.1111/cobi.13126">moral world</a>, and challenging the idea that only native species matter.</p><img src="https://counter.theconversation.com/content/159909/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arian Wallach receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Daniel Ramp receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Erick Lundgren 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>
Incredibly, once the wells dried up some became nurseries for the germination and establishment of wetland trees.
Erick Lundgren, Postdoctoral fellow, Aarhus University, University of Technology Sydney
Arian Wallach, Future Fellow, Queensland University of Technology
Daniel Ramp, Associate Professor and Director, Centre for Compassionate Conservation, University of Technology Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/152757
2021-02-08T14:14:30Z
2021-02-08T14:14:30Z
Fruit famine is causing elephants to go hungry in Gabon
<figure><img src="https://images.theconversation.com/files/379911/original/file-20210121-17-17htq8q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Forest elephants in Gabon</span> <span class="attribution"><span class="source">zahorec/Shutterstock</span></span></figcaption></figure><p>The behaviour and life cycles of the largest animals on the planet are <a href="https://www.nature.com/articles/s41467-020-14369-y">incredibly important</a> for the healthy functioning of our planet’s life support systems. Unfortunately, many big species now face extinction due to their value in the illegal wildlife trade, vulnerability to habitat degradation and because they often come into conflict with humans.</p>
<p>The African tropics host many of these remaining megafauna or large animals like gorillas, elephants and hippos, but they are now losing ground. African forest elephants, for instance, have a population <a href="https://doi.org/10.1371/journal.pone.0059469">just</a> 10% of their potential size, occupying 25% of their potential range.</p>
<p>Knowing how much influence these large animals have on the functioning of our world – and how vulnerable they are to extinction – it’s more important than ever to monitor and restore the health of their remaining populations and the safe havens that support them.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379906/original/file-20210121-21-zawy4a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Forest elephants drinking in the Djidji river, Ivindo National Park, Gabon.</span>
<span class="attribution"><span class="source">© Malcolm Starkey</span></span>
</figcaption>
</figure>
<p>We wanted to know how elephants are faring in Lopé National Park, a 5000 km² protected area in the heart of Gabon. Researchers at the site have observed some of the <a href="https://link.springer.com/article/10.1007/s10021-019-00424-3">highest densities</a> of forest elephants ever recorded.</p>
<p><a href="https://whc.unesco.org/en/list/1147">Lopé National Park</a> has a rich diversity of wildlife, including forest elephants, <a href="http://advances.sciencemag.org/content/4/4/eaar2964">chimpanzees, gorillas</a> and <a href="https://doi.org/10.1017/S0952836902001267">mandrills</a>. Many of these wildlife species rely on wild forest fruits for food. </p>
<p>In our <a href="https://doi.org/10.1126/science.abc7791">recently published paper</a> we analysed 32 years of valuable data about tree behaviour and found that – between 1986 and 2018 – there was a massive collapse in fruiting events.</p>
<p>This has resulted in a fruit famine and, based on a body condition score applied to archived photographs, an 11% decline in the physical condition of the elephants at our study area since 2008. </p>
<p>The implications of this finding are that even where forest elephants and other megafauna are relatively well protected from external threats such as <a href="http://dx.doi.org/10.1098/rsos.160498">hunting</a>, global human pressures – such as the climate crisis – could affect their survival. </p>
<p>A collapse in fruiting also means that the forests themselves may be undergoing significant change, with some trees species possibly reproducing slower than required to support a healthy population.</p>
<h2>Long-term research in Lopé National Park</h2>
<p>In 1986, pioneer primatologist Caroline Tutin <a href="https://carta.anthropogeny.org/users/caroline-tutin">started monitoring</a> food resources for wildlife at Lopé by recording monthly observations of flowers, fruit and leaves in the canopies of hundreds of marked trees. </p>
<p>Field researchers at the site still continue to record these <a href="https://doi.org/10.1111/btp.12543">observations</a> each month. This effort has resulted in the longest unbroken record of individual tree reproduction in the tropics, representing a priceless resource for monitoring environmental change.</p>
<p>Our analysis found that there was an 81% decline in the probability of encountering ripe fruit. This means that, on average, elephants and other animals would have found ripe fruit on one in every 10 trees in the 1980s, but need to search more than 50 trees today. We found matching declines in flowering too, indicating that the problem is not pollination or fruit maturation but something earlier on in the chain of fruit production.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=928&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=928&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=928&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1166&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1166&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379908/original/file-20210121-23-1w1vwdf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1166&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Omphalocarpum procerum with large fruits held directly on the stem at Lopé NP. Elephants are the only animal that can break open the fruit and disperse the seeds.</span>
<span class="attribution"><span class="source">© Nils Bunnefeld</span></span>
</figcaption>
</figure>
<p>Once we knew about this we had two questions: What is causing this decline? And what impact is this decline having on the many wildlife species that depend on fruit?</p>
<h2>Drop in physical condition</h2>
<p>Elephants are <a href="https://www.jstor.org/stable/5217">the largest</a> fruit-eating animals in the Central African forest ecosystem. They have an average biomass of over 3.5 tonnes at our site, meaning they require large amounts of food to satisfy their nutritional needs. They have a broad diet that includes fruit, grass, other vegetation and even tree bark, but previous <a href="https://doi.org/10.1111/j.1365-2028.1993.tb00532.x">research</a> at Lopé showed that fruit is dominant in their diet.</p>
<p>We collated a large photographic database of elephants dating back to 1997 (80,000 images) and invited experts in forest elephant ecology to assess the body condition of elephants in these images using a systematic scoring system. Using these newly-derived data we found an average 5% drop in physical condition of forest elephants at Lopé since the beginning of the photographic record in 1997, and a more concerning 11% decline since 2008. </p>
<p>We don’t yet know the consequences of this decline in body condition for elephant populations, but the effects are unlikely to be benign, especially when coupled with other <a href="https://doi.org/10.1111/cobi.12679">pressures</a> such as illegal hunting in the wider region.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379909/original/file-20210121-17-fkibal.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Elephants searching for food at the forest edge in Lopé National Park.</span>
<span class="attribution"><span class="source">© Anabelle Cardosso</span></span>
</figcaption>
</figure>
<h2>Is this climate change?</h2>
<p>Incredibly, before the climate crisis had become widely accepted as a threat to species and ecosystems, the changes illustrated in our paper were predicted by Caroline Tutin. In 1993 she <a href="https://www.jstor.org/stable/2559296#metadata_info_tab_contents">discovered</a> that some Lopé tree species depend on a critical drop in night-time temperatures during the long dry season to trigger flowering. In years when temperatures in the dry season did not dip below 19ºC these species produced no fruit and in an unusual year when this same drop in temperature occurred outside the dry season, some of these species produced fruit out of season. </p>
<p>Tutin suggested that as temperatures continued to increase – due to climate change – species such as these would be likely to reproduce less often if they missed out on this critical temperature to trigger flowering. </p>
<p>We don’t yet know for sure if this decline in fruiting is caused by climate change. However, <a href="https://peerj.com/articles/8732/">our previous work</a> shows that global warming has resulted in an increase of almost 1ºC in average night-time temperatures in Lopé during the study period.</p>
<h2>What now?</h2>
<p>The fruit famine witnessed at Lopé National Park could be happening across the African tropics but we have no concrete evidence because unfortunately long-term ecological data like these are very rare. </p>
<p>Maintaining support for consistent long-term monitoring is challenging and severely underfunded, <a href="https://www.nature.com/news/stormy-outlook-for-long-term-ecology-studies-1.16185">even in</a> richer parts of the world, despite the fact that this information is desperately needed to allow countries to prepare for and respond to environmental changes. </p>
<p>The year 2020 was supposed to be a turning point for the climate and biodiversity crises with both the <a href="https://www.cbd.int/article/Summit-on-Biodiversity-2020">UN Summit on Biodiversity</a> and <a href="https://www.unep.org/news-and-stories/video/climate-ambition-summit-2020">UN Climate Ambition Summit</a> scheduled to take place at the end of the year, but COVID-19 rightly took over the international agenda. However, with ever-increasing global temperatures and the approach of a <a href="https://ukcop26.org/">key UN Climate Change Conference</a> (COP26) in 2021, it’s vital that the world takes stock of the environmental situation. </p>
<p>We must make a concerted plan to transform the way we manage forests, food, fisheries and climate if we are to move towards a healthier and more sustainable world.</p><img src="https://counter.theconversation.com/content/152757/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Bush receives funding from Total Gabon (programmes on Green Gabon and Climate Change via the National Parks Agency) and the University of Stirling.</span></em></p><p class="fine-print"><em><span>Katharine Abernethy received funding that contributed to this research from Total Gabon (programmes on Green Gabon and Climate Change), the International Medical Centre in Franceville (CIRMF) and the University of Stirling. She is affiliated with the Gabon National Parks Agency and the National Centre for Scientific Research in Gabon. </span></em></p><p class="fine-print"><em><span>Robin Whytock was funded by the European Union's 11th FED ECOFAC6 program grant to the National Parks Agency of Gabon. He is currently employed by the University of Stirling.</span></em></p>
In Gabon’s Lopé National Park, between 1986 and 2018, there’s been a massive collapse in tree fruiting events.
Emma Bush, Scientist, Royal Botanic Garden Edinburgh
Katharine Abernethy, Professor, University of Stirling
Robin Whytock, Post Doctoral Research Fellow, University of Stirling
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/153094
2021-02-04T04:01:13Z
2021-02-04T04:01:13Z
This unique ancient megabeast had perpetually ‘bent’ elbows
<p>Imagine going through life with your arms permanently bent and locked at the elbows. Awkward, right? </p>
<p>Until recently we thought the mega-marsupial <a href="https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/600-million-years/timeline/quaternary/palorchestes/index.html"><em>Palorchestes azael</em></a> lived exactly like this. This rare, distant relative of the wombat became extinct (along with much of Australia’s megafauna) about 40,000 years ago.</p>
<p>But our research, published <a href="https://onlinelibrary.wiley.com/share/author/8GU9UT45FRETQ33CMXHV?target=10.1111/joa.13389">today in the Journal of Anatomy</a>, shows <em>Palorchestes</em> could in fact move its elbows — but only a very tiny amount compared to other mammals. </p>
<p>Thus, we think this enigmatic creature would have had a highly unusual gait, which may provide a clue to why it went extinct. </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>A strange setup</h2>
<p>The humble elbow has been around since the ancestors of all <a href="https://youtu.be/LcQdWIInnk8">four-limbed animals first hauled</a> themselves out of the water and onto land. </p>
<p>For most mammals, the elbow is a hinge-like joint that connects the humerus (which runs from shoulder to elbow) with the ulna and radius (which run from elbow to wrist). </p>
<p>The elbow allows the bending and straightening of the arm and is essential for four-legged walking. In the wild it’s also useful for tasks such as feeding, fighting, climbing and grooming. </p>
<p>But <em>Palorchestes</em> seemingly gave much of that up. Unlike other large mammals alive or extinct, it kept its arms in a perpetual “push-up” position.</p>
<p>So what would moving around have looked like for <em>Palorchestes</em>? And why might it have evolved such a narrow range of elbow motion in the first place? </p>
<h2>Peculiar <em>Palorchestes</em></h2>
<p><em>Palorchestes</em> was an unusual-looking marsupial. With a slender jaw indicating a long tongue and tiny nasal bones retracted high up in a narrow skull, some palaeontologists have suggested it had a tapir-like trunk (<a href="https://doi.org/10.1111/joa.13389">although others think this is unlikely</a>). </p>
<p>Fossils of <em>Palorchestes’s</em> robust bones show evidence of heavily muscled forelimbs with huge, sharp claws suited for clinging and tearing. And we recently found it may have grown to <a href="https://doi.org/10.1371/journal.pone.0221824">weigh more than a tonne</a>. </p>
<figure class="align-center ">
<img alt="Large fossil claw on a human palm." src="https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=520&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=520&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=520&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=653&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=653&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?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">
<figcaption>
<span class="caption">The massive claw bone of <em>Palorchestes azael</em> is equivalent to the bone we have in our fingertip. When <em>Palorchestes</em> was alive, this claw bone would have been covered by a keratin sheath that extended its length up to 50%.</span>
<span class="attribution"><span class="source">Hazel Richards</span></span>
</figcaption>
</figure>
<p>Still, for us the most interesting aspect of <em>Palorchestes</em> is its flattened elbow joint surfaces, which seem to indicate its elbows stayed bent at around a 100° angle.</p>
<p>We scanned the fossilised arm bones of <em>Palorchestes</em> and created computer simulations to model the full range of movements possible at its arm joint. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photographs of pangolin, sloth bear, anteater, wombat, koala, aardvark." src="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=655&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=655&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=655&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=823&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=823&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=823&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Palorchestes</em> had drastically less elbow mobility than the living mammals we compared it to. Clockwise from the top left: pangolin, sloth bear, anteater, wombat, koala and aardvark.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Our results indicate <em>Palorchestes</em> could move its elbows, but only in an off-axis motion that was tiny compared to other clawed mammals with chunky limbs such as wombats, pangolins, aardvarks and bears. Even its <a href="https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/600-million-years/timeline/quaternary/zygomaturus/index.html">closest extinct megafaunal relatives</a> had vastly more elbow function. </p>
<p>This suggests none of these creatures are good templates for understanding how <em>Palorchestes</em> moved.</p>
<p>By adding sliding movement as well as rotations, we used our 3D simulations to calculate the “average” motion in <em>Palorchestes</em>, from fully flexed to fully extended elbow poses. We found the axis of this small movement was skewed, like a “wonky” hinge. </p>
<p>The interactive below shows the maximum elbow motion that would have been theoretically possible for <em>Palorchestes azael</em>.</p>
<div class="sketchfab-embed-wrapper">
<iframe title="A 3D model" width="100%" height="480" src="https://sketchfab.com/models/fbf63a5f7b9b4011be63990cf4b2a242/embed?autostart=0&ui_controls=1&ui_infos=1&ui_inspector=1&ui_stop=1&ui_watermark=1&ui_watermark_link=1" frameborder="0" allow="autoplay; fullscreen; vr" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>
<p>
<a href="https://sketchfab.com/3d-models/maximum-elbow-motion-in-palorchestes-azael-fbf63a5f7b9b4011be63990cf4b2a242?utm_medium=embed&utm_source=website&utm_campaign=share-popup" target="_blank"></a>
</p>
</div>
<p>This skew means <em>Palorchestes</em> probably held its arms sprawled out from its body, allowing what little elbow mobility was possible to contribute to each stride while walking.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two possible forelimb postures for Palorchestes" src="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We modelled the whole range of motion possible at Palorchestes’s elbow to calculate its ‘average’ movement. If placed in a ‘normal’ mammal forelimb posture, <em>Palorchestes’s</em> hands would splay out to the sides as the elbows moved (left image). Instead, having forelimbs in a sprawled posture would have let its minute elbow movements contribute to each stride (right image)</span>
</figcaption>
</figure>
<h2>Arms akimbo make for awkward walking</h2>
<p>Our findings suggest <em>Palorchestes</em> would have trundled along on crouched forelimbs, with its elbows sprawled out to the sides — a highly inefficient gait compared with <a href="https://doi.org/10.1126/science.2740914">the pillar-like limbs</a> and tucked-in elbows of its relatives and large mammals alive today.</p>
<p>We think this posture was a compromise which let it use its strong arms and giant claws to access food in a specialised way, which was probably unique even back then.</p>
<p>While exact details remain a mystery, it could be that <em>Palorchestes</em> clung to tree trunks and hauled itself up onto its back legs to reach higher foliage with its long tongue. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Painting of Palorchestes rearing up against a tree" src="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=932&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=932&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=932&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1171&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1171&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1171&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 reconstruction of <em>Palorchestes azael</em> is from the 1980s. Although we now know the forelimb position shown here was highly unlikely, Palorchestes may have still used its strong arms and bent elbows to haul itself up against trees like this for better access to foliage.</span>
<span class="attribution"><span class="source">Peter Schouten</span></span>
</figcaption>
</figure>
<p>Or it might have used its huge, bulky body to push over tree ferns to access the young nutritious fronds higher up. </p>
<p>Whatever it did, <em>Palorchestes</em> was evidently pretty successful. While its fossils are rare, they’re widely distributed right across eastern Australia. </p>
<h2>The specialisation trap</h2>
<p>The fossils of <em>Palorchestes</em> tell us it was a specialist, highly adapted to a forest landscape. </p>
<p>Large animals have large appetites to match, but <em>Palorchestes’s</em> inefficient walk probably limited its ability to roam widely in search of food. </p>
<p>This would be no problem in times of plenty. But when shifts in Australia’s climate caused sweeping environmental changes across <a href="https://doi.org/10.1038/s41467-020-15785-w">the eastern half of the continent</a>, large specialised megafauna such as <em>Palorchestes</em> were especially vulnerable. </p>
<p>Even small changes in the vegetation mix would have made it difficult to find enough food.</p>
<figure class="align-center ">
<img alt="Lush Tasmanian forest with a Dicksonia tree fern and mossy logs" src="https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Palorchestes</em> probably lived in forests such as this one in Tasmania and may have used its specialised forelimbs to tear apart ferns and logs.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>So an adaptation that can be a recipe for success in one environment can lead to a <a href="https://doi.org/10.1093/icb/42.2.265">species’ demise in a changing world</a>. </p>
<p>And while there’s nothing like <em>Palorchestes</em> alive today, many unique species now face the same fate due to drastic changes in their habitats. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">Did people or climate kill off the megafauna? Actually, it was both</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/153094/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hazel L Richards is supported by an Australian Government Research Training Program scholarship and a Monash-Museums Victoria PhD top-up scholarship. </span></em></p><p class="fine-print"><em><span>Alistair Evans receives funding from Australian Research Council, and is an Honorary Research Affiliate at Museums Victoria.</span></em></p><p class="fine-print"><em><span>Justin W. Adams receives funding from the Australian Research Council and is a Research Associate with the Palaeo-Research Institute at the University of Johannesburg, South Africa.</span></em></p><p class="fine-print"><em><span>Peter Bishop receives funding from Harvard University and is an Honorary Researcher in the Geosciences Program of the Queensland Museum.</span></em></p><p class="fine-print"><em><span>David Hocking 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>
A new study shows Palorchestes had unique elbows unlike any other mammal, which may have contributed to its extinction.
Hazel L. Richards, PhD candidate, Monash University
Alistair Evans, Associate Professor, Monash University
David Hocking, Adjunct Research Associate, Monash University
Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University
Peter Bishop, Postdoctoral research fellow, Harvard Kennedy School
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/149746
2020-11-11T01:06:08Z
2020-11-11T01:06:08Z
Scientists thought these seals evolved in the north. 3-million-year-old fossils from New Zealand suggest otherwise
<p>A fossil discovery in New Zealand has revealed a new species of monk seal that once called Australasia home. We introduce the three million-year-old seal, <em>Eomonachus belegaerensis</em>, in a paper published today in the <a href="http://dx.doi.org/10.1098/rspb.2020.2318">Proceedings of the Royal Society B</a>. </p>
<p><em>Eomonachus</em> is the first monk seal species, living or extinct, ever found in the southern hemisphere — and the oldest found anywhere. </p>
<p>It’s rewriting everything experts thought they knew about the evolution of “monachines”, a group of seal relatives comprising the two living species of monk seal, the elephant seals, as well as certain species of Antarctic seals.</p>
<h2>On the brink of vanishing</h2>
<p>Monk seals are some of the world’s rarest and most endangered marine mammals. There are fewer than 2,100 <a href="https://www.mmc.gov/priority-topics/species-of-concern/mediterranean-monk-seal/">Mediterranean</a> and <a href="https://www.staradvertiser.com/2020/03/27/breaking-news/noaa-hawaiian-monk-seal-population-remained-steady-at-just-above-1400-in-2019/">Hawaiian</a> monk seals alive today. The Caribbean monk seal was <a href="https://www.sciencedaily.com/releases/2008/06/080608074828.htm">hunted to extinction</a> by the 1950s.</p>
<p>Conservationists are now scrambling to save what’s left of Earth’s last exclusively tropical seals from disappearing.</p>
<figure class="align-center ">
<img alt="A Hawaiian monk seal, and its pup, on a beach." src="https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368246/original/file-20201109-18-qvoamc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Hawaiian monk seal emerges from the surf. This is an endangered species of earless seal (Phocidae family) that’s endemic to the Hawaiian Islands.</span>
<span class="attribution"><span class="source">Robert Harcourt (Macquarie University)</span></span>
</figcaption>
</figure>
<p>That said, we would be wrong to assume monk seals were doing just fine before humans began exploiting them. How they fared over the past few million years remains unclear. We also don’t know where they originated, as fossils are few and far between.</p>
<p>Scientists traditionally thought all monk seals evolved in the North Atlantic Ocean. Before the discovery of <em>Eomonachus</em>, monk seals had only been found in the Northern Hemisphere. </p>
<p>In fact, most monachine fossils are found in the north, even though several living monachines (Antarctic seals and elephant seals) live <a href="https://www.publish.csiro.au/am/am11036">almost exclusively</a> in the Southern Ocean.</p>
<p>The unexpected discovery of <em>Eomonachus</em> has completely flipped the evolutionary history not only of monk seals, but of all monachines — by placing all three in the Southern Hemisphere for the first time. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/marine-species-are-more-threatened-than-we-thought-and-weve-only-looked-at-3-36914">Marine species are more threatened than we thought – and we've only looked at 3%</a>
</strong>
</em>
</p>
<hr>
<h2>A monk seal from New Zealand</h2>
<p>The recovery of the first known <em>Eomonachus</em> fossils came in the form of seven skulls uncovered along the coast of Taranaki, on New Zealand’s North Island. The fossils were retrieved by local collectors and donated to the <a href="https://www.tepapa.govt.nz/">Te Papa Tongarewa</a> and <a href="https://www.canterburymuseum.com/">Canterbury</a> museums. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=313&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=313&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=313&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=394&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=394&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368486/original/file-20201110-22-zc7lxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=394&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The seven fossilised skulls of the extinct monk seal species <em>Eomonachus</em>.</span>
<span class="attribution"><span class="source">Erich Fitzgerald (Museums Victoria)</span></span>
</figcaption>
</figure>
<p>Our team eventually named the species <em>Eomonachus belegaerensis</em>. This translates to “dawn monk seal from Belegaer”. Belegaer is the fictional sea that lies west of “Middle Earth”, the land from J. R. R. Tolkein’s Lord of The Rings trilogy which is often associated with New Zealand.</p>
<p>But what were monk seals doing in New Zealand three million years ago? </p>
<p>Well, in the past, southern oceans were a lot warmer than they are today. And ancient monk seals, much like their modern relatives, lived in subtropical waters. </p>
<p>But until <a href="https://theconversation.com/in-a-land-of-ancient-giants-these-small-oddball-seals-once-called-australia-home-144574">this year</a>, few scientific studies on extinct monachines had been conducted in the southern hemisphere. This is likely why <em>Eomonachus</em> eluded scientists for so long.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-a-land-of-ancient-giants-these-small-oddball-seals-once-called-australia-home-144574">In a land of ancient giants, these small oddball seals once called Australia home</a>
</strong>
</em>
</p>
<hr>
<h2>The evolution of monachines</h2>
<p>Following the unveiling of <em>Eomonachus</em>, we decided to re-investigate the evolution of the monachines. </p>
<p>Our research indicates this group of seals evolved in the Southern Hemisphere after all. This is in contrast with every theory previously put forward by scientists.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A picture of James Rule holding one of the monk seal fossils." src="https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368243/original/file-20201109-21-c1qo1p.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">Monash University palaeontologist James Rule with one of the <em>Eomonachus</em> skull fossils found in New Zealand.</span>
<span class="attribution"><span class="source">Erich Fitzgerald/Museums Victoria</span></span>
</figcaption>
</figure>
<p>If there is indeed a southern origin for monachines, this would mean the group crossed the equator at least eight times throughout its evolutionary history.</p>
<p>However, the warm waters at the equator are widely accepted to be a thermal barrier which is difficult for <a href="https://theconversation.com/northern-exposure-fossils-of-a-southern-whale-found-for-the-first-time-in-the-north-85254">marine mammals to cross</a>. </p>
<p>If past monachines did jump between both hemispheres, they would have had broad environmental tolerances that let them do this. And this would have enabled their dispersal around the world. </p>
<p>It’s difficult to say conclusively whether modern seals share this trait, but we do know it’s rare for them to cross the equator during their lifetime.</p>
<h2>Climate change and seal extinction</h2>
<p>So why aren’t monk seals living around New Zealand now?</p>
<p>About 2.5 million years ago, marine megafauna experienced an <a href="https://www.popsci.com/marine-megafauna-mass-extinction/">extinction event</a>, thought to have been caused by a drop in sea levels as a result of falling global temperature.</p>
<p>Previous research has theorised this change in climate spurred the extinction of many <a href="https://lens.monash.edu/@science/2020/04/04/1379872/rare-fossil-tooth-discovery-reveals-extinct-group-of-seals">ancient seals</a> in the Southern Hemisphere. This would have included <em>Eomonachus</em>, as well as other extinct monachines.</p>
<p>This suggests the world’s last two species of monk seal, vestiges of what was once likely a widespread group, are also at risk from climate change. </p>
<p>If sea levels continue to rise, the beaches monk <a href="https://theconversation.com/unlocking-the-mystery-of-how-true-seals-disappeared-from-the-cape-44344">seals rely on</a> for resting and breeding may disappear. Rising temperatures could also <a href="https://theconversation.com/climate-change-could-drive-coastal-food-webs-to-collapse-76798">disrupt food webs</a>, making it difficult for them to find food. </p>
<p>While the discovery of <em>Eomonachus</em> is exciting, it can also be considered a cautionary tale.</p><img src="https://counter.theconversation.com/content/149746/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>Felix Georg Marx received funding from Australian Research Council DECRA fellowship (DE190101052).</span></em></p><p class="fine-print"><em><span>Erich Fitzgerald and Justin W. Adams 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>
This newly discovered ancient monk seal is challenging previous theories about how and where monachine seals evolved. It’s the biggest breakthrough in seal evolution research in about 70 years.
James Patrick Rule, Palaeontology PhD Candidate, Monash University
Erich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria Research Institute
Felix Georg Marx, Curator Vertebrates, Te Papa Tongarewa
Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/148541
2020-10-29T07:44:54Z
2020-10-29T07:44:54Z
Colourful opal fossils point to a diverse group of giant dinosaurs that shared Australia’s terrain
<p>North-central New South Wales today is known for its arid, drought-prone climate. During the <a href="https://www.livescience.com/29231-cretaceous-period.html">Cretaceous period</a>, however, it was a lush coastal floodplain with a <a href="https://www.sciencedirect.com/science/article/pii/S0031018218305960">high diversity of vertebrates</a> including dinosaurs, crocodiles, turtles and soaring <a href="https://theconversation.com/4-metre-flying-reptile-unearthed-in-queensland-is-our-best-pterosaur-fossil-yet-124581">pterosaurs</a>.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A typical landscape of the late Cretaceous Period." src="https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366080/original/file-20201028-15-1svjbzb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australian landscapes during the Cretaceous Period would have been much unlike today’s.</span>
<span class="attribution"><a class="source" href="https://australian.museum/learn/australia-over-time/evolving-landscape/the-cretaceous-period/">Karen Carr/Australian Museum</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>New insights gleaned from opalised teeth, found near the town of Lightning Ridge, are now helping paint a picture of the most enormous dinosaurs to ever roam the planet: <a href="https://www.britannica.com/animal/sauropod">sauropods</a>.</p>
<p>Our work, published today in the journal <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/let.12407">Lethaia</a>, reveals up to three different sauropod species once lived in the region, feeding at different heights within the forest canopy. </p>
<h2>Scintillating and sizeable specimens</h2>
<p>Opalised fossils are natural casts made entirely out of opal. While they generally don’t preserve the original organism, they do preserve its shape.</p>
<p>In Lightning Ridge, opalised fossils are a <a href="https://www.smithsonianmag.com/science-nature/scientists-and-miners-team-up-preserve-opalized-fossils-180972734/">rich source of palaeontological information</a>. For decades, miners have excavated these fossils — including the sauropod teeth we studied — from deep underground its opal fields.</p>
<p>The sauropods were a group of dinosaur species with markedly long necks, long tails and a herbivorous diet. Potentially weighing up to <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001853">90,000 kg</a>, they were the largest animals to have ever walked the Earth. </p>
<p>Sauropods were an extremely important component of the known vertebrate fauna in northern Australia. Until recently, we knew of four named species from Queensland: <a href="https://www.nature.com/articles/srep34467"><em>Savannasaurus elliotorum</em></a>, <a href="https://www.sciencedirect.com/science/article/pii/S1342937X14001051"><em>Diamtinasaurus matildae</em></a>, <a href="https://www.tandfonline.com/doi/pdf/10.1080/03115518.2017.1334826?casa_token=jOI9RnOWrDsAAAAA:Ns8YeY-zyG8wJfGkIlRw1vq-M2Y3pk-z-COe0_37cg3diw3mgNlUY0gG8RvF2dO-adYyLfA8_AhboA"><em>Austrasaurus mckillopi</em></a> and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006190"><em>Wintonotitan wattsi</em></a>. </p>
<p>However, whether this diversity was unique to Queensland, or extended into more southern regions, remained unknown.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-savannasaurus-australias-newest-titanosaur-67383">Meet Savannasaurus, Australia's newest titanosaur</a>
</strong>
</em>
</p>
<hr>
<h2>The wisdom in studying teeth</h2>
<p>For our study, we examined 25 sauropod tooth fossils aged between <a href="https://www.sciencedirect.com/science/article/abs/pii/S0031018218305960?casa_token=p-U_WSyb38QAAAAA:zcAHyLOdhgD83lvJdbVb3kPdRseXxp533FVxbqVwhm4txCkrBTtajl7f1-SdrrXf-4RsB9Q7dII">95-100 million years old</a>. From these, we identified five “morphotypes”, or tooth-shape categories. Several features of a tooth can define its morphotype, including its symmetry, the presence or absence of grooves and wear patterns. </p>
<p>Humans have multiple morphotypes within their mouths, such as molars for grinding, incisors for nipping and canines for grasping. But unlike humans, we know all the teeth of sauropod species would have served similar functions and would have thus had little variation.</p>
<p>This is good news for us, because it means we can be pretty confident sauropod tooth fossils with different shapes came from different species.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=265&fit=crop&dpr=1 600w, https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=265&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=265&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=333&fit=crop&dpr=1 754w, https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=333&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/365481/original/file-20201026-23-8ull5o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=333&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Five sauropod teeth fossils (not to scale) showing the diversity of tooth shapes found at Lightning Ridge. The fossils have different colours since they’re all made out of opal.</span>
<span class="attribution"><span class="source">Timothy Frauenfelder</span></span>
</figcaption>
</figure>
<p>We interpreted three of the five morphotypes in our fossil collection as coming from the upper jaw and the other two from the lower jaw. By comparing our fossils with those from more completely studied sauropods, we were able to link them with at least three distinct species that would have cohabited the area around what is now Lightning Ridge. </p>
<p>While we couldn’t assign the 25 tooth fossils to specific species (as we’d need more than just teeth to identify a dinosaur species), we do know all the teeth belonged to a large group of sauropods known as Titanosauriformes. </p>
<p>This group included the late Jurassic <em>Brachiosaurus</em>, which famously reared-up on its hind legs in the 1993 movie Jurassic Park. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/WROrnCt8NF4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">You may remember this iconic <em>Brachiosaurus</em> scene from Jurassic Park.</span></figcaption>
</figure>
<p>Also, one of the morphotypes likely came from a later subgroup of Titanosauriformes, called Titanosauria. This group contained species such as the truly gigantic dinosaurs <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001853"><em>Argentinosaurus</em></a> and <a href="https://www.theatlantic.com/science/archive/2017/08/is-this-really-the-biggest-dinosaur-ever-discovered/536187/"><em>Patagotitan</em></a>.</p>
<h2>A tooth tells the truth</h2>
<p>Tooth fossils aren’t only useful to gauge past diversity, but also to infer diets of long-extinct animals. The dietary link is evident since teeth are the primary tool for obtaining and processing food.</p>
<p>When studying teeth, one way we can interpret diets is through looking for “microwear”. This refers to an assortment of small features found on teeth from tooth-to-food or tooth-to-tooth contact. </p>
<p>These features can be preserved in tooth fossils as scratches or pits visible on worn surfaces. Specifically, the ratio of scratches to pits can indicate the grittiness, or smoothness, of a dinosaur’s diet. </p>
<p>More pits means more grit (dust minerals) in the diet. This shows feeding took place closer to the ground. Conversely, more scratches indicates a diet of smoother food, such as foliage, found higher in the forest canopy.</p>
<p>While microwear patterns of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0018304">North American sauropods</a> have been extensively researched, this is the first time they’ve been observed in sauropods from Australia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Rendering of two Savannasauruses." src="https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366320/original/file-20201029-23-1ixqmg4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Savannasaurus elliottorum</em> (nicknamed ‘Wade’) — the only species in the Savannasaurus genus — was one of several long-necked sauropods that existed in Queensland during the mid-Cretaceous period.</span>
<span class="attribution"><a class="source" href="https://www.australianageofdinosaurs.com/page/2/australian-age-of-dinosaurs-terms-conditions">Travis Tischler/Australian Age of Dinosaurs Museum of Natural History</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Zooming in on pits and scratches</h2>
<p>From our collection, two tooth fossils had preserved microwear features. The others were either not worn or had their microwear features obliterated during the opalisation process.</p>
<p>Interestingly, the fossils that did preserve microwear also had different morphotypes. This suggests at least two of the three sauropod species that once roamed NSW were able to coexist by consuming different food within the forest canopy.</p>
<p>One species had a higher proportion of scratches than pits, so it likely fed on soft vegetation between 1-10m above the ground. The other had a higher proportion of pits, which suggests it ate harder vegetation less than 1m above the ground.</p>
<p>Our research may have been limited to teeth, but it demonstrates even incomplete fossils can provide key insights into the lives of long-extinct creatures. </p>
<p>Importantly, it discloses the fascinating sauropod diversity that once inhabited New South Wales, previously identified only in Queensland.</p>
<p>Much like animals today, we believe their coexistence would have depended on them eating different foods in the same area. This would have led to a colourful, cosmopolitan dinosaur landscape in a past, much different, Australia. </p>
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Read more:
<a href="https://theconversation.com/has-dinosaur-dna-been-found-an-expert-explains-what-we-really-know-133017">Has dinosaur DNA been found? An expert explains what we really know</a>
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<p><em>Acknowledgements: we’d like to thank the Australian Opal Centre and the Australian Museum for supplying the fossils for our research.</em></p><img src="https://counter.theconversation.com/content/148541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy Frauenfelder received funding from Dr Phil Bell's Australian Research Council grant. </span></em></p><p class="fine-print"><em><span>Nicolas Campione receives funding from the Australian Research Council. </span></em></p>
Tooth fossils from NSW have confirmed sauropods weren’t exclusive to Queensland. They’re also providing a first look at how these colossal dinosaurs fed from Australia’s land.
Timothy Frauenfelder, PhD Candidate in Palaeontology, University of New England
Nicolas Campione, Research Fellow/Lecturer, University of New England
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/147656
2020-10-07T19:10:21Z
2020-10-07T19:10:21Z
It was growing rainforests, not humans, that killed off Southeast Asia’s giant hyenas and other megafauna
<figure><img src="https://images.theconversation.com/files/362096/original/file-20201007-14-1ciu27.jpeg?ixlib=rb-1.1.0&rect=56%2C56%2C4159%2C3148&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Peter Schouten</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Thinking of Southeast Asia today may conjure up images of dense tropical rainforests teeming with iconic jungle animals such as orangutans, tigers and monkeys.</p>
<p>Perhaps less well known, but just as important to these ecosystems, are a host of other large-bodied creatures: the goat-like <a href="https://en.wikipedia.org/wiki/Serow">serows</a> and <a href="https://en.wikipedia.org/wiki/Goral">gorals</a>, <a href="https://www.wwf.org.uk/learn/wildlife/asian-rhinos">three species of Asian rhino</a> and the only species of <a href="https://en.wikipedia.org/wiki/Malayan_tapir">tapir</a> still living in the “Old World”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tapir sitting in a green forest." src="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.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>
<figcaption>
<span class="caption">The endangered Malayan tapir is the largest of four widely-recognized tapir species and the only one native to Asia.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Together, these creatures comprise Southeast Asia’s megafauna, second only to Africa’s in diversity. These two continental ecosystems are the last vestiges of a world largely lost – one where giants roamed the Earth. But what caused so many megafauna species to go extinct?</p>
<p>Several theories have suggested either humans, climate change, or both drove Southeast Asia’s megafauna to extinction. However, our newest research published today in <a href="https://www.nature.com/articles/s41586-020-2810-y">Nature</a> indicates it was actually the rise and fall of savannah environments that drove this extinction event.</p>
<h2>Southeast Asia’s megafauna extinctions</h2>
<p>Southeast Asia has lost many large mammal species over the Quaternary period, the past 2.6 million years. They included the world’s largest ever ape, <em><a href="https://en.wikipedia.org/wiki/Gigantopithecus">Gigantopithecus</a></em>, elephant-like creatures known as <a href="https://en.wikipedia.org/wiki/Stegodon">stegodons</a> and large water buffaloes.</p>
<p>These extinctions also include one of our closest relatives, <em>Homo erectus</em>, and two island offshoots of the human family tree – <em>Homo floresiensis</em> (the “Hobbit”) and <em>Homo luzonensis</em>. One final human species is also recorded in the genes of Southeast Asians today: the Denisovans, who were once <a href="https://cosmosmagazine.com/palaeontology/southeast-asia-was-crowded-long-before-we-turned-up/">likely widespread throughout the region</a>.</p>
<p>According to <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">previous research</a>, the lead antagonist in the megafauna extinction story is humans. Some have suggested the arrival of people to new lands over the past 60,000 years or more – who then overhunted and altered this new habitat – is what led to the loss of giant mammals. </p>
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Read more:
<a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">New analysis finds no evidence that climate wiped out Australia's megafauna</a>
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<p>Others researchers have contended <a href="https://theconversation.com/humans-coexisted-with-three-tonne-marsupials-and-lizards-as-long-as-cars-in-ancient-australia-138534">changes in climate</a> resulted in the extinction of the megafauna. While others suggest a <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">combination</a> of both human and climate influences. </p>
<h2>Toothy insights into past environments</h2>
<p>For our research, we examined environmental changes in Southeast Asia over the <a href="https://www.nationalgeographic.com/science/prehistoric-world/quaternary/">past 2.6 million years</a>, to determine how they may have impacted extinctions. </p>
<p>We analysed the <a href="https://www.futurelearn.com/courses/archaeology/0/steps/15267">stable isotopes</a> of the teeth of mammals found in the region today, as well as those from available published fossil records.</p>
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<p>
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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>
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<p>Stable isotopes are the non-radioactive forms of many elements. Stable isotopes of carbon and oxygen preserved in mammal teeth record important information on what kinds of plants those animals ate, and how wet their environments were, respectively. </p>
<p>Stable carbon isotopes are particularly helpful in recording whether animals predominantly ate leaves and fruits in shaded forests, or grasses in more open settings. This insight lets us identify shifts in environments over time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ancient tooth fossils." src="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These fossil teeth from extinct Southeast Asian elephants are one example of the various teeth available in the fossil record.</span>
<span class="attribution"><span class="source">Julien Louys</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The fluctuating presence of forests</h2>
<p>During the first 1.5 million years or so of the Pleistocene (the geological epoch that lasted from about 2,580,000 to 11,700 years ago), the northern parts of Southeast Asia were largely forest, while the southern parts were woodlands or grasslands. </p>
<p>Later, from about one million years ago, forests retreated everywhere in the region and grasslands dominated. Coincident with these changes, large forest-adapted animals including <em>Gigantopithecus</em> and a giant panda relative disappeared from Southeast Asia’s northern parts.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Model recreation of Gigantopithecus blacki." src="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Gigantopithecus blacki</em> was a large extinct ape that lived during the Pleistocene in what is now Southern China. It’s believed to have gone extinct about 300,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/22077805@N07/5484933159/in/photostream/">Greg Williams/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Later still, around 400,000 years ago, the Southeast Asian Sunda Shelf began to submerge and climate cycles changed. Because of this, forest conditions returned.</p>
<p>At the same time, grassland-adapted creatures that had filled the region, including giant hyenas, <a href="http://www.eartharchives.org/articles/stegodon-the-elephant-with-sideways-trunk/">stegodons</a>, <a href="https://www.britannica.com/animal/bovid">bovids</a> and <em>Homo erectus</em> began to disappear – and largely went extinct by the end of the Pleistocene. The remainder were driven into the rainforests. </p>
<p>By the last few tens of thousands of years, we see the first evidence of <a href="https://en.wikipedia.org/wiki/Stratification_(vegetation)">stratified</a>, closed-canopy rainforests in Southeast Asia. These have dominated the region for the past 20,000 years or so.</p>
<p>Rainforest-adapted species should have been advantaged by the return of the rainforests, but one interloper changed that. <em>Homo sapiens</em> appears to be the only species in our family tree that was able to successfully adapt to and exploit rainforest environments. </p>
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Read more:
<a href="https://theconversation.com/old-teeth-from-a-rediscovered-cave-show-humans-were-in-indonesia-more-than-63-000-years-ago-82075">Old teeth from a rediscovered cave show humans were in Indonesia more than 63,000 years ago</a>
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<p>And although humans lived in Southeast Asian rainforests as early as 73,000 years ago, it was probably only <a href="https://advances.sciencemag.org/content/4/6/e1701422">in the last 10,000 years</a> that <em>Homo sapiens</em> began to fundamentally alter these habitats and exploit the mammals within. </p>
<h2>A vanishing world</h2>
<p>Southeast Asia continues to preserve some of the most critically endangered megafauna on the planet. </p>
<p>Megafauna grassland specialists were the greatest loss as a result of disappearing savannahs 400,000 years ago. Today, rainforest megafauna are also at great risk of extinction. </p>
<p>Luckily for us, our own species’ fortunes changed for the better with the emergence of typical Southeast Asian rainforests. But we’re now the very thing threatening to <a href="https://theconversation.com/guns-snares-and-bulldozers-new-map-reveals-hotspots-for-harm-to-wildlife-113361">destroy them forever</a>.</p><img src="https://counter.theconversation.com/content/147656/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Patrick Roberts receives funding from the Max Planck Society and the European Research Council.</span></em></p>
Several theories have suggested either humans, climate change or both drove megafauna extinctions in Southeast Asia. Our newest work suggests otherwise.
Julien Louys, ARC Future Fellow, Griffith University
Patrick Roberts, Research Group Leader, Max Planck Institute of Geoanthropology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/141296
2020-06-25T20:14:17Z
2020-06-25T20:14:17Z
Meet 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>
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<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 Salford
Julien Louys, ARC Future Fellow, Griffith University
Mike Archer, Professor, Pangea Research Centre, UNSW Sydney
Philippa Brewer, Senior Curator, Natural History Museum
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/138534
2020-05-18T02:44:29Z
2020-05-18T02:44:29Z
Humans coexisted with three-tonne marsupials and lizards as long as cars in ancient Australia
<figure><img src="https://images.theconversation.com/files/335484/original/file-20200516-138620-otfni1.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C2400%2C1353&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Life and death in tropical Australia, 40,000 years ago. Giant reptiles ruled northern Australia during the Pleistocene with mega-marsupials as their prey.
Image Credit: R. Bargiel, V. Konstantinov, A. Atuchin & S. Hocknull (2020). Queensland Museum</span> </figcaption></figure><p>When people first arrived in what is now Queensland, they would have found the land inhabited by massive animals including goannas six metres long and kangaroos twice as tall as a human.</p>
<p>We have studied fossil bones of these animals for the past decade. Our findings, <a href="https://dx.doi.org/10.1038/s41467-020-15785-w">published today in Nature Communications</a>, shed new light on the mystery of what drove these ancient megafauna to extinction. </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>
<p>The first bones were found by the Barada Barna people during cultural heritage surveys on their traditional lands about 100 kilometres west of Mackay, at South Walker Creek Mine. Our study shares the first reliable glimpse of the giants that roamed the Australian tropics between 40,000 and 60,000 years ago. </p>
<p>These megafauna were the largest land animals to live in Australia since the time of the dinosaurs. Understanding the ecological role they played and the environmental impact of their loss remains their most valuable untold story.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335497/original/file-20200516-138624-1q7tpxq.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">Fossils are found eroding out of the ancient flood plains of South Walker Creek.</span>
<span class="attribution"><span class="source">Rochelle Lawrence, Queensland Museum.</span></span>
</figcaption>
</figure>
<p>While megafauna lived at South Walker Creek, people had arrived on the continent and were spreading across it. Our study adds new evidence to the ongoing megafauna extinction debate, but importantly underscores how much is left to learn from the fossil record. </p>
<h2>The megafauna welcoming party</h2>
<p>We excavated fossils from four sites and made detailed studies of the sites themselves to find the age of the fossils and understand what the environment was like in the past. </p>
<p>Our findings give us an idea of what megafaunal life was like in the tropical Australian savanna over a period of about 20,000 years, from around 60,000 to 40,000 years ago. During this time, the northern megafauna were different to those from the south. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=131&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=131&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=131&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=165&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=165&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335494/original/file-20200516-138629-13zmtq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=165&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mega-reptiles of Pleistocene tropical Australia.</span>
<span class="attribution"><span class="source">V. Konstantinov, A. Atuchin, R. Allen, S. Hocknull. Queensland Museum.</span></span>
</figcaption>
</figure>
<p>We have found at least 13 extinct species so far at <a href="https://sketchfab.com/queenslandmuseum/collections/tropical-megafauna-of-south-walker-creek">South Walker Creek</a>, with mega-reptiles as apex predators, and mega-mammals their prey. Many of the species discovered are likely new species or northern variations of their southern counterparts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=148&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=148&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=148&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=186&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=186&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335495/original/file-20200516-138654-1yvfrsl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=186&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mega-mammals from Pleistocene tropical Australia.</span>
<span class="attribution"><span class="source">V. Konstantinov, A. Atuchin, S. Hocknull. Queensland Museum.</span></span>
</figcaption>
</figure>
<p>Some, like the extinct crocodiles, were thought to have gone extinct long before people were on the scene. However, we now know they survived in at least one place 60,000-40,000 years ago.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=761&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=761&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=761&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=957&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=957&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335496/original/file-20200516-138639-10nzxey.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=957&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 giant kangaroo of South Walker Creek may be the largest kangaroo ever found. Pictured here next to the previous titleholder, <em>Procoptodon goliah</em>. Scale bar equals 1 m.</span>
<span class="attribution"><span class="source">V. Konstantinov, A. Atuchin, R. Allen, S. Hocknull. Queensland Museum.</span></span>
</figcaption>
</figure>
<p>Imagine first sighting a six-metre goanna and its Komodo Dragon-sized relative, or bumping into a land-dwelling crocodile and its plate-mail armoured aquatic cousin. The mammals were equally bizarre, including a giant bucktoothed wombat, a strange “bear-sloth” marsupial, and enormous kangaroos and wallabies. </p>
<p>A yet-to-be named giant <a href="https://sketchfab.com/queenslandmuseum/collections/giant-kangaroos-from-south-walker-creek">kangaroo</a> is the largest ever found. With an estimated mass of 274 kg, it beats the previous contender, the goliath short-faced kangaroo, <em>Procoptodon goliah</em>. </p>
<p>The biggest of all the mammals was the three-tonne marsupial <em><a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">Diprotodon</a></em>, and the deadliest was the pouched predator <em>Thylacoleo</em>. Living alongside these giants were other megafauna species that still survive today: the emu, the red kangaroo and the saltwater crocodile. </p>
<h2>Whodunnit? The evidence points to environmental change</h2>
<p>Why did these megafauna become extinct? It has been argued that the extinctions were due to <a href="https://science.sciencemag.org/content/292/5523/1888">over-hunting</a> by humans, and occurred shortly after people arrived in Australia. </p>
<p>However, this theory is not supported by our finding that a diverse collection of these ancient giants still survived 40,000 years ago, after humans had spread around the continent.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=496&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=496&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=496&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=623&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=623&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335506/original/file-20200516-138649-1eiche.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=623&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossil seeds, leaves and insects help palaeontologists reconstruct the megafauna’s environment. Scale bar equals 1 mm.</span>
<span class="attribution"><span class="source">Paul Tierney, Queensland Museum.</span></span>
</figcaption>
</figure>
<p>The extinctions of these tropical megafauna occurred sometime after our youngest fossil site formed, around 40,000 years ago. The timeframe of their disappearance coincided with sustained regional changes in available water and vegetation, as well as increased fire frequency. This combination of factors may have proven fatal to the giant land and aquatic species. </p>
<p>The megafauna extinction debate will no doubt continue for years to come. New discoveries will plug up the key <a href="https://www.nature.com/articles/d41586-018-05330-7">gaps</a> in the record. With the gaps in the north of the continent the greatest yet to fill. </p>
<p>With an overlap between people and megafauna of some 15,000–20,000 years, new questions arise about co-habitation. How did people live with these giants during a period of such drastic environmental change?</p>
<h2>How much more change can Australia bear?</h2>
<p>Major environmental change and extinctions are not an unusual part of our geological past, but this time it’s personal; it involves us. Throughout the Pleistocene (the time that ended with the most recent ice age), Australia has undergone major climatic and environmental change. </p>
<p>Within the same catchment of these new megafauna sites, one <a href="https://doi.org/10.1016/j.epsl.2007.10.004">study</a> shows how major climatic upheaval beginning around 280,000 years ago caused the disappearance of a diverse rainforest fauna. This set in motion a sequence of changes to the ecosystem that culminated in the loss of the megafauna at South Walker Creek around 40,000 years ago.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">Did people or climate kill off the megafauna? Actually, it was both</a>
</strong>
</em>
</p>
<hr>
<p>It’s still unclear what impact these long-term environmental changes and the loss of the megafauna had on the species that survived. </p>
<p>This long-term trend of extinctions has now been given a kick along by the major changes to the environment created by humans which continue today. In the early 21st century in Australia we have seen increases in floods, droughts and bushfires, and we expect these increases to continue. </p>
<p>The fossil record provides us with a window into our past that can help us understand our <a href="https://www.frontiersin.org/articles/10.3389/fevo.2017.00011/full">present</a>. As our study shows, dramatic environmental change takes a heavy toll on species survival especially for those at the top of the food chain. Will we heed the warnings from the past or suffer the consequences?</p><img src="https://counter.theconversation.com/content/138534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scott Hocknull receives funding from Queensland Museum and Queensland Museum Foundation.</span></em></p><p class="fine-print"><em><span>Anthony Dosseto receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Gilbert Price receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Lee Arnold receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Patrick Moss receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Renaud Joannes-Boyau receives funding from the Australian Research Council</span></em></p>
These megafauna were the largest land animals to live in Australia since the time of the dinosaurs.
Scott Hocknull, Senior Curator of Geosciences, Queensland Museum, and Honorary Research Fellow, The University of Melbourne
Anthony Dosseto, Professor, University of Wollongong
Gilbert Price, Lecturer in Palaeontology, The University of Queensland
Lee Arnold, Associate Professor in Earth Sciences, University of Adelaide
Patrick Moss, Professor, The University of Queensland
Renaud Joannes-Boyau, Senior research fellow, Southern Cross University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/132627
2020-04-29T15:48:10Z
2020-04-29T15:48:10Z
How bison, moose and caribou stepped in to do the cleaning work of extinct mammoths
<figure><img src="https://images.theconversation.com/files/330714/original/file-20200427-145560-nibdjc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3777%2C2050&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Unlike mammoths, bison survived in Alaska at the end of the last ice age.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/QvCcqTHlLCE">Hans Veth/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The extinction of one species can create ripples that transform an ecosystem. That’s particularly true for so-called “ecosystem engineer” species. Beavers are one example – they dam rivers, creating ponds and channels that <a href="https://theconversation.com/beavers-are-set-to-recolonise-the-uk-heres-how-people-and-the-environment-could-benefit-132116">offer refuge for spawning fish and small mammals</a>.</p>
<p>Large herbivores such as <a href="http://thinkelephants.blogspot.com/2012/10/elephants-ecosystems-engineers.html">elephants, horses and reindeer</a> are engineers too – they break down shrubs and trees to create open grasslands, habitats that benefit a wealth of species.</p>
<p>We know that their ancestors – such as the woolly mammoth – shaped the world around them in a similar way, but what happened to those ancient ecosystems when they died out?</p>
<p>Our <a href="https://www.cambridge.org/core/journals/quaternary-research/article/tracking-latequaternary-extinctions-in-interior-alaska-using-megaherbivore-bone-remains-and-dung-fungal-spores/BD3C13789FBB262EDCA8432CBB47067E">new research published in the journal Quaternary Research</a> studied the extinction of mammoth, wild horse and saiga antelope towards the end of the last ice age in interior Alaska, analysing fossilised <a href="https://methodsblog.com/2016/07/19/european-bison/">dung fungal spores</a> recovered from the bottom of lakes and <a href="https://www.nps.gov/articles/aps-17-1-4.htm">ancient bones recovered from buried</a> sediments.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-effect-did-the-asteroid-that-wiped-out-the-dinosaurs-have-on-plants-and-trees-132386">Curious Kids: What effect did the asteroid that wiped out the dinosaurs have on plants and trees?</a>
</strong>
</em>
</p>
<hr>
<p>We wanted to know how ancient ecosystems responded to these species dying out so that it might teach us more about mass extinctions today. What we discovered could offer hope for modern ecosystems facing biodiversity loss.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=435&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=435&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=435&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A museum replica of a woolly mammoth. Mammoths helped maintain open habitats by grazing herbs, trees and bushes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dvur-kralove-czech-republic-08132013-big-1024532596">Noska Photo/Shutterstock</a></span>
</figcaption>
</figure>
<h2>How ancient ecosystems coped with extinctions</h2>
<p>The late-Quaternary extinctions occurred towards the end of the last ice age. In North America, they saw the loss of large herbivores and carnivores, whose relatives still roam other continents as elephants, wild horses and tigers. This was a period of rapid climate change and growing pressure from humans.</p>
<p><a href="https://www.researchgate.net/publication/269820457_Late_Quaternary_megafaunal_extinctions_on_the_continents_A_short_review">Previous research showed that 69% of large mammals</a> were lost from North America around this time. Similar losses were seen on other continents, <a href="https://www.discovermagazine.com/planet-earth/dung-fungus-reveal-that-humans-not-climate-change-killed-australias-giant-beasts">including Australia</a>. The diversity of mammal species shrank, but more significant was the <a href="https://doc.rero.ch/record/210391/files/PAL_E4398.pdf">crash in numbers of all mammals</a>, including species that survived the extinction event.</p>
<p><a href="https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.12576">Previous research</a> showed that elsewhere in the Americas, the loss of ecosystem engineers like the woolly mammoth led to an explosion in plant growth, as trees and shrubs were no longer grazed and browsed so intensively. In turn, there were larger and more frequent wildfires.</p>
<p>But in Alaska, our results revealed that other species of wild herbivores, including bison, moose, caribou and musk ox, increased in abundance, making up for the loss of mammoths, saiga antelopes and wild horses.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=509&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=509&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=509&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=639&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=639&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=639&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Saiga antelopes used to roam North America, but they are now only found in scattered pockets of Asia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Saiga_antelope#/media/File:Saiga_antelope_at_the_Stepnoi_Sanctuary.jpg">Andrey Giljov/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This suggests that as extinctions occurred, other large herbivores were able to fill the gap, partially taking over the lost role of ecosystem engineer. This insight from 13,000 years ago could offer hope for modern conservationists. Substituting an extinct ecosystem engineer with a similar species still living today may work to revive lost ecological processes.</p>
<p>Reintroducing large herbivores in this way is often referred to as “<a href="https://www.esf.edu/efb/parry/Invert_Cons_14_Readings/Seddon_etal_2014.pdf">rewilding</a>”. Today’s landscapes on most continents are <a href="https://www.chrispackham.co.uk/news/what-is-rewilding">empty of large vertebrate animals</a>, largely because of the late Quaternary extinctions we studied. <a href="https://www.researchgate.net/publication/257973653_Rewilding_North_America">One of the key arguments</a> behind rewilding is that bringing some of those species back to landscapes could boost biodiversity more broadly and create more diverse, resilient ecosystems.</p>
<p>But without resurrecting the woolly mammoth, our research indicates it may be possible to bring back some of the ecosystem engineering benefits of extinct species by reintroducing their living relatives or substitute species, ultimately helping surviving plants and animals to thrive.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/could-resurrecting-mammoths-help-stop-arctic-emissions-95956">Could resurrecting mammoths help stop Arctic emissions?</a>
</strong>
</em>
</p>
<hr>
<p>Our work in Alaska shows that the consequences of engineer extinctions are not always overwhelmingly negative. Studying this rare instance when ecosystems coped better with extinctions can help us design more effective conservation measures for megaherbivores today. </p>
<p>A good example of creative thinking in conservation can be found in Columbia. Here, pet hippos that escaped from Pablo Escobar’s private collection have multiplied in the wild and now appear to be recreating processes that were <a href="https://www.theguardian.com/environment/2020/mar/24/pablo-escobars-cocaine-hippos-show-how-invasive-species-can-restore-a-lost-world-aoe">lost thousands of years ago</a> when native megaherbivores died out. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.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">These hippos are technically invasive species in Colombia and are wild descendants of Pablo Escobar’s pets.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hippopotamus-colombia-1351698167">Perla Sofia/Shutterstock</a></span>
</figcaption>
</figure>
<p>This includes the creation of well trodden hippo paths between wetlands and feeding areas on firmer ground, which help deepen water channels, disperse seeds and fertilise wetlands. Over 13,000 years ago, these processes would have been carried out by the now extinct <a href="https://prehistoric-fauna.com/Macrauchenia-patagonica">giant llama</a>, and semi-aquatic <a href="https://dcpaleo.org/notoungulata/">notoungulata</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Notoungulata were hoofed, sometimes heavy-bodied grazing mammals that inhabited South America from 57 million years to 11,000 years ago.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Notoungulata#/media/File:Toxodon.jpg">ArthurWeasley/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Although it may seem an eternity since mammoths walked the Earth, our research suggests that some of the effects they had on the world around them can be resurrected without a Jurassic Park-style breakthrough in <a href="https://www.thoughtco.com/the-resurrection-of-extinct-animals-1091999">de-extinction</a>.</p><img src="https://counter.theconversation.com/content/132627/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maarten van Hardenbroek van Ammerstol receives funding from UKRI/NERC. </span></em></p><p class="fine-print"><em><span>Ambroise Baker 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>
The historical record is full of surprises – and it could encourage conservationists to think more creatively.
Ambroise Baker, Lecturer in Biology, Teesside University
Maarten van Hardenbroek van Ammerstol, Lecturer in Physical Geography, Newcastle University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/128799
2020-01-03T09:36:46Z
2020-01-03T09:36:46Z
How the extinction of ice age mammals may have forced us to invent civilisation
<figure><img src="https://images.theconversation.com/files/307690/original/file-20191218-11900-s0uqmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Hunting_Woolly_Mammoth.jpg">Wikimedia Commons/Cloudordinary</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Why did we take so long to invent civilisation? Modern <em>Homo sapiens</em> first evolved roughly <a href="https://theconversation.com/modern-humans-evolved-100-000-years-earlier-than-we-thought-and-not-just-in-east-africa-78875">250,000 to 350,000</a> years ago. But initial steps towards civilisation – harvesting, then domestication of crop plants – began only <a href="https://science.sciencemag.org/content/288/5471/1602?ijkey=3c1b653d8a610f044ce71bd2e41594fe7be12060&keytype2=tf_ipsecsha">around 10,000 years ago</a>, with the first civilisations appearing <a href="https://link.springer.com/article/10.1007/s10814-010-9041-y">6,400 years ago</a>.</p>
<p>For 95% of our species’ history, we didn’t farm, create large settlements or complex political hierarchies. We lived in small, nomadic bands, hunting and gathering. Then, something changed. </p>
<p>We transitioned from hunter-gatherer life to plant harvesting, then cultivation and, finally, cities. Strikingly, this transition happened only after the ice age megafauna – mammoths, giant ground sloths, giant deer and horses – disappeared. The reasons humans began farming still <a href="https://phys.org/news/2019-04-food-thought-farming.html">remain unclear</a>, but the disappearance of the animals we depended on for food may have forced our culture to evolve. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=494&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=494&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=494&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Humans hunted wild cattle, horses, and deer in France 17,000 years ago.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
</figcaption>
</figure>
<p>Early humans were smart enough to farm. All groups of modern humans have similar levels of intelligence, suggesting our cognitive capabilities evolved before these populations separated <a href="https://science.sciencemag.org/content/358/6363/652/tab-pdf">around 300,000 years ago</a>, then changed little afterwards. If our ancestors didn’t grow plants, it’s not that they weren’t clever enough. Something in the environment prevented them – or they simply didn’t need to. </p>
<p>Global warming at the end of the last glacial period, 11,700 years ago, probably <a href="https://www.cambridge.org/core/journals/american-antiquity/article/was-agriculture-impossible-during-the-pleistocene-but-mandatory-during-the-holocene-a-climate-change-hypothesis/246B240BFFFBE904B1AC31296AD72949">made farming easier</a>. Warmer temperatures, longer growing seasons, higher rainfall and <a href="https://www.journals.uchicago.edu/doi/pdfplus/10.1086/605359">long-term climate stability</a> made more areas suitable for cultivation. But it’s unlikely farming had been impossible everywhere. And Earth saw <a href="https://science.sciencemag.org/content/292/5517/686">many such warming events</a> – 11,700, 125,000, 200,000 and 325,000 years ago – but earlier warming events didn’t spur experiments in farming. Climate change can’t have been the only driver.</p>
<p>Human migration probably contributed as well. When our species expanded from southern Africa throughout <a href="https://science.sciencemag.org/content/358/6363/652/tab-pdf">the African continent</a>, into <a href="https://www.nature.com/articles/nature22968">Asia</a>, Europe and then <a href="https://science.sciencemag.org/content/365/6456/891">the Americas</a>, we found new environments and <a href="https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2012.04253.x">new food plants</a>. But people occupied these parts of the world long before farming began. Plant domestication lagged human migration by tens of millennia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.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">Rye, one of the first crops.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
</figcaption>
</figure>
<p>If opportunities to invent farming already existed, then the delayed invention of agriculture suggests our ancestors didn’t need, or want, to farm.</p>
<p>Agriculture has significant disadvantages compared to foraging. Farming <a href="https://www.discovermagazine.com/planet-earth/the-worst-mistake-in-the-history-of-the-human-race">takes more effort and offers less leisure time and an inferior diet</a>. If hunters are hungry in the morning, they can have food on the fire at night. Farming requires hard work today to produce food months later – or not at all. It requires storage and management of temporary food surpluses to feed people year round. </p>
<p>A hunter having a bad day can hunt again tomorrow or seek richer hunting grounds elsewhere, but farmers, tied to the land, are at the mercy of nature’s unpredictability. Rains arriving too soon or too late, droughts, frosts, blights or locusts can cause crop failure – and famine. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Agriculture has many disadvantages over hunting.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Ancient_Egyptian_agriculture#/media/File:Maler_der_Grabkammer_des_Sennudem_001.jpg">Wikipedia</a></span>
</figcaption>
</figure>
<p>Agriculture has military disadvantages as well. Hunter-gatherers are mobile and can travel long distances to attack or retreat. Constant practice with spears and bows made them <a href="https://theconversation.com/were-other-humans-the-first-victims-of-the-sixth-mass-extinction-126638">deadly fighters</a>. Farmers are rooted to their fields, their schedules dictated by the seasons. They are predictable, stationary targets, whose food stockpiles tempt hungry outsiders.</p>
<p>And having evolved to the lifestyle, humans may simply have loved being nomadic hunters. The Comanche Indians <a href="https://www.amazon.com/dp/B003KN3MDG/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1">fought to the death</a> to preserve their hunting lifestyle. The Kalahari Bushmen of southern Africa <a href="https://www.bbc.co.uk/news/world-africa-24821867">continue to resist</a> being turned into farmers and herders. Strikingly, when Polynesian farmers encountered New Zealand’s abundant flightless birds, they largely abandoned agriculture, creating the Maori <a href="https://teara.govt.nz/en/1966/maori-material-culture">moa-hunter culture</a>.</p>
<h2>Hunting abandoned</h2>
<p>Yet something changed. From 10,000 years ago onward, humans repeatedly abandoned the hunter-gatherer lifestyle for farming. It may be that after the extinction of mammoths and other megafauna from the Pleistocene epoch, and the overhunting of surviving game, the hunter-gatherer lifestyle became less viable, pushing people to harvest and then cultivate plants. Perhaps civilisation wasn’t born out of a drive to progress, <a href="https://www.penguinrandomhouse.com/books/112492/plagues-and-peoples-by-william-h-mcneill/">but disaster</a>, as ecological catastrophe forced people to abandon their traditional lifestyles.</p>
<p>As humans left Africa to colonise new lands, large animals disappeared everywhere we set foot. In Europe and Asia, megafauna like wooly rhinos, mammoths, and Irish Elk vanished <a href="https://www.researchgate.net/profile/Adrian_Lister/publication/264785182_Patterns_of_Late_Quaternary_megafaunal_extinctions_in_Europe_and_northern_Asia/links/53f0e69f0cf2711e0c431517.pdf">around 40,000 to 10,000 years ago</a>. In Australia, giant kangaroos and wombats disappeared <a href="https://science.sciencemag.org/content/292/5523/1888">46,000 years ago</a>. In North America, horses, camels, giant armadillos, mammoths and ground sloths declined and disappeared from <a href="https://science.sciencemag.org/content/326/5956/1100.full">15,000 to 11,500 years ago</a>, followed by extinctions in South America <a href="https://www.sciencedirect.com/science/article/pii/S1040618209004236">14,000 to 8,000 years ago</a>. After people spread to the Caribbean Islands, <a href="https://www.pnas.org/content/100/19/10800.short">Madagascar</a>, <a href="https://www.sciencedirect.com/science/article/pii/S0277379114003734">New Zealand</a> and <a href="https://science.sciencemag.org/content/217/4560/633">Oceania</a>, their megafauna vanished as well. Megafaunal extinctions inevitably followed humans.</p>
<p>Harvesting big game like <a href="https://www.pnas.org/content/112/14/4263.short">horses, camels</a> and <a href="https://science.sciencemag.org/content/334/6054/351">elephants</a> produces <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">a better return</a> than hunting small game like rabbits. But large animals like elephants reproduce slowly, and have few offspring compared to small animals like rabbits, <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">making them vulnerable to overharvesting</a>. And so everywhere we went, our human ingenuity – hunting with spear-throwers, herding animals with fire, stampeding them over cliffs – meant we harvested large animals faster than they could replenish their numbers. It was arguably the first sustainability crisis. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.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">With our hunting prey gone, we were forced to invent civilisation.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/egypt-sakkara-step-pyramid-king-djoser-109821740">WitR/Shutterstock</a></span>
</figcaption>
</figure>
<p>With the old way of life no longer viable, humans would have been forced to innovate, increasingly focusing on <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">gathering, then cultivating plants to survive</a>. This let human populations expand. Eating plants rather than meat is <a href="https://www.google.com/search?q=jared+diamong+third+chimpanzee&rlz=1C5CHFA_enGB841GB841&oq=jared+diamong+third+chimpanzee&aqs=chrome..69i57j35i39l2j0l4j69i60.4797j0j7&sourceid=chrome&ie=UTF-8">a more efficient use of land</a>, so farming can support more people in the same area than hunting. People could settle permanently, build settlements, then civilisations. </p>
<p>The archaeological and fossil records tell us our ancestors could have pursued farming, but did only so after they had little alternative. We probably would have continued hunting horses and mammoths forever, but we were just too good at it, and likely wiped out our own food supply.</p>
<p>Agriculture and civilisation may have been invented not because they were an improvement over our ancestral lifestyle, but because we were left no choice. Agriculture was desperate attempt to fix things when we took more than the ecosystem could sustain. If so, we abandoned the life of ice age hunters to create the modern world, not with foresight and intent, but by accident, because of an ecological catastrophe we created thousands of years ago.</p><img src="https://counter.theconversation.com/content/128799/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas R. Longrich 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>
Overhunting of megafauna such as mammoths may have force us to take up farming, ultimately leading to modern society
Nicholas R. Longrich, Senior Lecturer, Paleontology and Evolutionary Biology, University of Bath
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/127803
2019-12-03T18:36:08Z
2019-12-03T18:36:08Z
Did people or climate kill off the megafauna? Actually, it was both
<figure><img src="https://images.theconversation.com/files/304383/original/file-20191129-45248-1sspxz7.jpg?ixlib=rb-1.1.0&rect=4%2C9%2C1497%2C1116&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When freshwater dried up, so did many megafauna species.</span> <span class="attribution"><a class="source" href="https://epicaustralia.org.au">Centre of Excellence for Australian Biodiversity and Heritage</a>, <span class="license">Author provided</span></span></figcaption></figure><p>Earth is now firmly in the grips of its sixth “mass extinction event”, and it’s mainly <a href="https://theconversation.com/radical-overhaul-needed-to-halt-earths-sixth-great-extinction-event-68221">our fault</a>. But the modern era is definitely not the first time humans have been implicated in the extinction of a wide range of species.</p>
<p>In fact, starting about 60,000 years ago, many of the world’s largest animals disappeared forever. These “<a href="https://australianmuseum.net.au/learn/australia-over-time/megafauna/">megafauna</a>” were first lost in <a href="http://sahultime.monash.edu.au/explore.html">Sahul</a>, the supercontinent formed by Australia and New Guinea during periods of low sea level. </p>
<p>The causes of these extinctions have been debated for decades. Possible culprits include <a href="https://theconversation.com/climate-change-wiped-out-australias-megafauna-13966">climate change</a>, <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">hunting or habitat modification by the ancestors of Aboriginal people</a>, or a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2015.2399">combination of the two</a>.</p>
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<p>
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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>The main way to investigate this question is to build timelines of major events: when species went extinct, when people arrived, and when the climate changed. This approach relies on using <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">dated fossils from extinct species</a> to estimate when they went extinct, and archaeological evidence to determine <a href="https://theconversation.com/an-incredible-journey-the-first-people-to-arrive-in-australia-came-in-large-numbers-and-on-purpose-114074">when people arrived</a>. </p>
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<p>
<em>
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Read more:
<a href="https://theconversation.com/an-incredible-journey-the-first-people-to-arrive-in-australia-came-in-large-numbers-and-on-purpose-114074">An incredible journey: the first people to arrive in Australia came in large numbers, and on purpose</a>
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<p>Comparing these timelines allows us to deduce the likely windows of coexistence between megafauna and people.</p>
<p>We can also compare this window of coexistence to long-term models of climate variation, to see whether the extinctions coincided with or shortly followed abrupt climate shifts.</p>
<h2>Data drought</h2>
<p>One problem with this approach is the scarcity of reliable data due to the extreme rarity of a dead animal being fossilised, and the low probability of archaeological evidence being preserved in Australia’s harsh conditions.</p>
<p>This means many studies are restricted to making conclusions regarding drivers of extinction at the scale of single palaeontological sites or of specific archaeological sites. </p>
<p>Alternatively, timelines can be constructed by including evidence across large spatial scales, such as over the <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">entire continent of Australia</a>. </p>
<p>Unfortunately, this “lumping” of the available evidence across many different sites disregards the variation in the relative contribution of different extinction drivers across the landscape.</p>
<h2>Mapping extinction</h2>
<p>In our <a href="https://www.nature.com/articles/s41467-019-13277-0">research published in Nature Communications</a>, we developed advanced mathematical tools to map the regional patterns of the timing of megafauna disappearances and the arrival of Aboriginal ancestors across south-eastern Australia. </p>
<p>Based on these new maps, we can now work out where humans and megafauna coexisted, and where they did not. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=653&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=653&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=653&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=821&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=821&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304225/original/file-20191128-178078-mo80fk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=821&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Areas of coexistence and non-coexistence between humans and megafauna.</span>
<span class="attribution"><span class="source">F. Saltré</span></span>
</figcaption>
</figure>
<p>It turns out humans coexisted with the megafauna over about 80% of south-eastern Sahul for up to 15,000 years, depending on the region in question. </p>
<p>In other regions such as Tasmania, there was no such coexistence. This rules out humans as a likely driver of megafauna extinction in those areas. </p>
<p>We then aligned these windows of coexistence and non-coexistence in each part of the landscape with several environmental measures derived from climate simulations over the past 120,000 years. This gave us an idea about which factors best explained the timing of megafauna extinction in each part of the landscape. </p>
<p>Despite a major effect on extinctions in areas where megafauna and people did not coexist, there was nothing at all to explain the timing of megafauna extinctions in places where megafauna and people coexisted. </p>
<p>This surprising result suggested that we had missed something important in our analyses.</p>
<h2>Connecting the dots</h2>
<p>The major flaw in our approach was to analyse each location independently of its surroundings. Our initial model had failed to take account of the fact that an extinction in one place can affect an extinction in another location nearby. </p>
<p>Once we changed our model to incorporate these effects, the real picture finally emerged. We found that megafauna extinctions in areas were they coexisted with humans were most likely caused by a combination of human pressure and access to water.</p>
<p>In the other 20% of the landscape, where humans and megafauna did not coexist, we found that extinctions likely occurred because of a lack of plants, driven by increasingly dry conditions. This doomed many plant-eating megafauna species to extinction. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304380/original/file-20191129-45296-yb8dhl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Relative importance (in %) of variables best describing the timing (first row) and the directional gradient (second row) of megafauna extinction in areas of non-coexistence (first column) and coexistence (second column) of people and megafauna.</span>
<span class="attribution"><span class="source">F. Saltré</span></span>
</figcaption>
</figure>
<h2>Space is key</h2>
<p>This is the first evidence that tens of thousands of years ago, the combination of humans and climate change was already making species more likely to disappear. Yet this pattern was invisible if we ignored the interconnectedness of the various regions involved. </p>
<p>This might be just the beginning we need for a new, more nuanced treatment of environmental change in the deep past in other regions of the world.</p>
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Read more:
<a href="https://theconversation.com/11-000-scientists-warn-climate-change-isnt-just-about-temperature-126261">11,000 scientists warn: climate change isn't just about temperature</a>
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<p>More importantly, our results reinforce <a href="https://theconversation.com/11-000-scientists-warn-climate-change-isnt-just-about-temperature-126261">scientists’ stark warning</a> about the immediate future of our planet’s plants and wildlife. Given rising human pressures on the natural world, coupled with an unprecedented pace of global warming, modern species are facing similar ravages.</p><img src="https://counter.theconversation.com/content/127803/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Corey J. A. Bradshaw receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Frédérik Saltré and Katharina J. Peters 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>
A drying climate and the arrival of people together finished off Australia’s megafauna.
Frédérik Saltré, Research Fellow in Ecology & Associate Investigator for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University
Corey J. A. Bradshaw, Matthew Flinders Fellow in Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University
Katharina J. Peters, Postdoctoral Fellow, Flinders University
Licensed as Creative Commons – attribution, no derivatives.