tag:theconversation.com,2011:/global/topics/gondwana-1965/articles
Gondwana – The Conversation
2024-01-28T19:03:27Z
tag:theconversation.com,2011:article/221589
2024-01-28T19:03:27Z
2024-01-28T19:03:27Z
Banksias are iconic Australian plants, but their ancestors actually came from North Africa
<figure><img src="https://images.theconversation.com/files/571053/original/file-20240124-19-b1td3b.jpg?ixlib=rb-1.1.0&rect=41%2C57%2C5416%2C3608&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/a-yellow-flower-with-green-leaves-on-a-branch-wmy7IFiAQZQ">Sandie Peters/Unsplash</a></span></figcaption></figure><p>Few plants conjure up the Australian bush better than banksias, whose beautiful flowers are irresistible to honeyeater birds, small marsupials and nature lovers.</p>
<p>But our research, published in <a href="https://doi.org/10.1016/j.ppees.2024.125778">Perspectives in Plant Ecology, Evolution and Systematics</a>, shows that the ancestors of banksias actually migrated here from North Africa. </p>
<p>From <a href="https://doi.org/10.1093/aob/mcad055">early fossil pollen studies</a>, we already knew that the protea family (Proteaceae), which includes banksias, grevilleas, waratahs and macadamias in Australia, originated in northwest Africa 130 million years ago. </p>
<p>Our task was to track their migration to Australia, where they became the unique symbols of the Australian bush that we admire today. To give credit where it’s due, we need to know where our natural heritage originated. So, how did this iconic group of plants get here?</p>
<h2>Looking at the entire family</h2>
<p>Our study relied on two approaches. We used a DNA assessment of the entire protea family to create an evolutionary tree. Then we inserted key fossil pollen records of a known age into the tree, to serve as a “molecular clock”. This helped us work out the time of origin of all genera in this family.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An orange-pink flower resembling a bottle brush" src="https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=748&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=748&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=748&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=940&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=940&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571077/original/file-20240124-27-trdrd4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=940&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>Banksia hookeriana</em>, the most important species used in the wildflower trade in Western Australia and now widely planted. This is the most studied of all members of the protea family.</span>
<span class="attribution"><span class="source">Byron Lamont</span></span>
</figcaption>
</figure>
<p>We then searched the literature for records of ancient sedimentary deposits that contain fossil pollen with affinities to banksias in Africa, South America, Antarctica (which was covered in forest until 40 million years ago) and Australia. </p>
<p>This was made possible by the fact the <a href="https://www.britannica.com/science/pollen">hard walls of pollen grains</a> allow them to be preserved for millions of years. Also, the pollen grains of plants in the protea family are <a href="https://doi.org/10.1071/SB97022">quite distinctive</a> from those of other families. We then compared the dates and locations of the fossil pollen against our family tree.</p>
<p>This showed that by 120 million years ago, the ancestors of banksias had begun crossing into northeast South America. The two continents remained joined at their tips until 100 million years ago.</p>
<p>The plants then migrated down the east side of South America – first reaching the Scotia Isthmus about 110 million years ago – and crossed onto the Antarctic Peninsula. </p>
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Read more:
<a href="https://theconversation.com/the-coastal-banksia-has-its-roots-in-ancient-gondwana-138434">The coastal banksia has its roots in ancient Gondwana</a>
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</em>
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<h2>Two routes into Australia</h2>
<p>Here, the ancestors separated into two groups. One, the soft-leaved group, followed a cool-temperate rainforest pathway (dark for up to four months of the year) along the south side of Antarctica. They entered Australia via Tasmania from 105 million years ago. </p>
<p>The rainforest elements continued up the east coast, with some eventually reaching New Guinea; <a href="https://doi.org/10.1126/sciadv.1501648">others entered New Caledonian rainforests</a> directly from southern Antarctica. This route remained open until 45 million years ago, when Australia and Antarctica finally separated. </p>
<p>The other, hard-leaved group followed an open, fire-prone woodland pathway along the warmer, sunnier northern side of Antarctica. They entered Australia via the southwest tip that remained attached to Antarctica until about 70 million years ago. </p>
<p>The two points of entry were separated by a huge inland sea that occupied the Great Australian Bight during that period.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571078/original/file-20240124-25-yrlux.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">Migratory pathway taken by the ancestors of banksias beginning 132 million years ago in north Africa. Note how the ancestors split into two groups on entering Antarctica from South America, banksia itself entering via southwest Australia and the rainforest species via Tasmania.</span>
<span class="attribution"><span class="source">Modified from Lamont et al. (2024) Perspectives in Plant Ecology Evolution and Systematics</span></span>
</figcaption>
</figure>
<h2>A proliferation of banksias</h2>
<p>Since banksia itself appears to have arisen 100 million years ago, the genus either evolved in northeast Antarctica or at the extreme corner of southwestern Australia. From there, they spread to the rest of Australia over the next 50 million years.</p>
<p>Banksias now consist of <a href="https://anpsa.org.au/genera/banksia/">around 200 species</a>, 90% of which are endemic to southwestern Australia. Ancestors of the bulk of the hard-leaved genera, such as grevilleas, hakeas, macadamias and waratahs, also entered Australia via the southwestern tip. They then migrated east along the margins of the Nullarbor Plain – thickly vegetated back then – to southeast Australia.</p>
<p>Until the results of our new study, it was believed the protea family arose in Australia and spread from here to Africa, South America, New Caledonia and Asia. Almost all migration would have needed to be over the oceans, as it was thought to have happened after the breakup of the Gondwanan supercontinent. </p>
<p>In fact, the journey was entirely overland as it occurred when Gondwana was largely intact, except for the early departure of Greater India.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=523&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=523&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571079/original/file-20240124-15-c2155i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=523&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Banksia shrubland 300km north of Perth, Western Australia. Three species of banksia, about 1.5 metres tall, are present in this image as well as several other members of the protea family, such as <em>Adenanthos</em> and <em>Xylomelum</em>.</span>
<span class="attribution"><span class="source">Byron Lamont</span></span>
</figcaption>
</figure>
<h2>Plants out of Africa</h2>
<p>Anthropologists are keen to point to the “<a href="https://australian.museum/learn/science/human-evolution/the-first-migrations-out-of-africa/">out of Africa</a>” hypothesis for the origin and <a href="https://theconversation.com/new-path-for-early-human-migrations-through-a-once-lush-arabia-contradicts-a-single-out-of-africa-origin-214719">migratory history of humans</a>. It now appears such a hypothesis is equally applicable to some important groups of plants.</p>
<p>This is the first time the southwest corner of Australia has been recognised as a major migratory route for the protea family.</p>
<p>We now need to take seriously the Antarctic–southwest Australian link as a likely major entry route for many other hard-leaved plant groups into Australia. They could have originated in Antarctica and South America, and possibly even Africa.</p>
<p>This north Antarctic pathway might well also apply to eucalypts, whose oldest records are for southern South America, as well as currently endemic animals and microbes.</p><img src="https://counter.theconversation.com/content/221589/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Byron Lamont receives funding from the Australian Research Council </span></em></p><p class="fine-print"><em><span>Lynne Milne is a member of the Australian and New Zealand Forensic Society and the American Association of Stratigraphic Palynologists. She is currently the Treasurer of the Royal Societies of Australia. </span></em></p><p class="fine-print"><em><span>Tianhua He received funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Richard Cowling 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>
Today, these plants are iconic to the Australian bush. But banksias and their many relatives originated in far-away shores 130 million years ago.
Byron Lamont, Distinguished Professor Emeritus in Plant Ecology, Curtin University
Lynne Milne, Curtin University
Richard Cowling, Professor, Nelson Mandela University
Tianhua He, Senior lecturer, Murdoch University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/215809
2023-11-12T19:15:42Z
2023-11-12T19:15:42Z
Australia has more native bird species than almost anywhere else. What led to this explosion of diversity?
<figure><img src="https://images.theconversation.com/files/554661/original/file-20231019-17-zkff5l.jpg?ixlib=rb-1.1.0&rect=26%2C62%2C3465%2C2727&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An Opalton grasswren.</span> <span class="attribution"><span class="source">Barry Baker</span></span></figcaption></figure><p>When you went out today, did you see any birds? A galah perhaps, or a crow?</p>
<p>If you did, there’s a decent chance the bird you saw lives nowhere but Australia. Out of about <a href="https://www.dcceew.gov.au/sites/default/files/env/pages/2ee3f4a1-f130-465b-9c7a-79373680a067/files/nlsaw-2nd-complete.pdf">850 species</a> found in Australia, 45% are “endemic”, which means they’re unique to Australia. The only other country with <a href="https://iopscience.iop.org/article/10.1088/1755-1315/473/1/012064">more endemic species</a> is Indonesia.</p>
<p>Thanks to their wings, birds are the world’s greatest travellers. So why is it that such a high proportion of Australian birds aren’t found anywhere else?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=692&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=692&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=692&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=869&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=869&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554664/original/file-20231019-21-r60wx5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=869&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A little raven (<em>Corvus mellori</em>) in the Nullarbor. These birds are native to South-East Australia and are related to Australia’s crows.</span>
<span class="attribution"><span class="source">Barry Baker</span></span>
</figcaption>
</figure>
<h2>Climate rules</h2>
<p>The story starts <a href="https://www.antarctica.gov.au/about-antarctica/geography-and-geology/geology/">more than 45 million</a> years ago, when Australia first split from Antarctica and started to head north. It was the events that occurred during this trip – particularly in relation to our climate – that led to the diversity in Australia’s birds today. </p>
<p>When it first set out, Australia was covered in lush rainforest. As it drifted, however, the climate became much drier. Our distinctive flora of grasslands and eucalypt woodlands started to spread across the continent. </p>
<p>But this drying trend wasn’t consistent. Particularly in the last million years, dry periods associated with the ice ages alternated with wetter times, such as the <a href="https://www.smithsonianmag.com/science-nature/what-is-the-anthropocene-and-are-we-in-it-164801414/">Holocene epoch</a> – which is what we’ve had for the past 10,000 or so years.</p>
<p>But the climate didn’t just vary over thousands of years. It also varied, as we know too well, from year to year. Australia has long been the land of long droughts, sometimes lasting decades, interspersed with flooding rains.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554662/original/file-20231019-23-dlbl1a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Opalton grasswrens (<em>Amytornis rowleyi</em>) can be found in the Forsyth Range in Queensland.</span>
<span class="attribution"><span class="source">Barry Baker</span></span>
</figcaption>
</figure>
<h2>What’s climate got to do with birds?</h2>
<p>The diversity in Australia’s birds arose partly because of the list of passengers aboard the good ship of Australia. This included ancient parrots and the ancestors of what were to become the world’s first songbirds: the <a href="https://www.unediscoveryvoyager.org.au/2022/05/30/lyrebirds-really-are-superb/">lyrebirds and scrub-birds</a>. Both groups are highly adaptable and have <a href="https://www.tandfonline.com/doi/abs/10.1071/MU13034">bigger brains</a> than other birds relative to their size.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=857&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=857&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=857&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1076&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1076&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554673/original/file-20231019-17-pyeh6o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1076&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lyrebirds are known for their incredible mimicry.</span>
<span class="attribution"><span class="source">Barry Baker</span></span>
</figcaption>
</figure>
<p>However, it was ultimately the climate that gave us so many endemic species. Every time the climate dried, birds that preferred forests were pushed to the damper margins of the continent, where they evolved into separate species. In wetter times, some forests spread and reconnected – but now there were two or more species, not just one. </p>
<p>The same was true for the arid land birds, which got divided when it became extra dry. One ancient group called grasswrens <a href="https://www.bushheritage.org.au/species/grass-wrens">has different species</a> in almost all the isolated blocks of arid habitat across the country.</p>
<p>The parrots and cockatoos also diversified into a huge range of species, from tiny budgerigars to <a href="https://www.australiangeographic.com.au/topics/wildlife/2019/03/australias-five-black-cockatoos/">huge black cockatoos</a>.</p>
<h2>One-way traffic</h2>
<p>But that’s only part of the story. You might have heard of the original supercontinent, Pangaea, which <a href="http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/p_pangaea2.html">split into Gondwana and Laurasia</a> about 200 million years ago. When <a href="https://nre.tas.gov.au/Documents/Gondwana.pdf">Gondwana eventually split</a>, some of the continents moved north and shared their faunas with the regions they ran into in the Northern Hemisphere.</p>
<p>As Africa and India collided with Asia and Europe, the species from the old supercontinents of Gondwana and Laurasia mixed. <a href="https://www.livescience.com/planet-earth/when-did-the-isthmus-of-panama-form-between-north-and-south-america">North and South America</a> also exchanged plants and animals when their land masses joined. Australia was different. And once again, it came down to the climate. </p>
<p>As Australia pushed north, the shifting tectonic plates threw up islands that acted as stepping stones to Asia. These allowed Australian songbirds to <a href="https://theconversation.com/how-songbirds-island-hopped-their-way-from-australia-to-colonise-the-world-64616">head out into</a> the wider world, where they did exceptionally well. In fact, <a href="https://www.pnas.org/doi/10.1073/pnas.1813206116">researchers think</a> all the world’s 5,000 or songbird species came from Australia.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OGdPqpzYD4o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This animation shows the continent of Pangaea breaking into the land masses we have today.</span></figcaption>
</figure>
<p>The question is, why was this traffic one way? Why didn’t Asian and American birds such as woodpeckers hop on over to Australia? One reason could be that by that time Australia was already full of tough birds that had evolved to cope with a pretty mean climate. </p>
<p>In contrast, the birds from Asia had evolved in fertile rainforests. Any that did disperse south along the chain of islands leading to Australia would have been ill-equipped to cope with its aridity. They would also have had to compete with parrots and songbirds that already knew how to take full advantage of the resources available.</p>
<p>A few did make it, including a lovely <a href="https://www.australiaswonderfulbirds.com.au/finches">set of finches</a>, but they are an exception proving the rule. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554688/original/file-20231019-17-sm97lb.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">Zebra finches (<em>Taeniopygia castanotis</em>) are the most common of Australia’s grassfinches, found across most of the mainland.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Budgies are the best</h2>
<p>It’s probably no coincidence the world’s most popular cage birds come from Australia. Cage living isn’t for every bird; most birds are delicate creatures that need constant care if bred in captivity.</p>
<p>In contrast, budgerigars, cockatiels and zebra finches from Australia’s fickle arid zone know they must do what it takes while the going’s good, because the next El Niño may start next week. And it helps if you can cope with temperatures that vary from -10°C to more than 40°C. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=735&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=735&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=735&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=923&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=923&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554666/original/file-20231019-17-r60wx5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=923&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 budgerigar (<em>Melopsittacus undulatus</em>) is a colourful native parrot.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Australia also shares many bird species with New Guinea. This isn’t surprising, given we’re on the same continental plate. </p>
<p>The Torres Strait is so shallow that drops in sea levels during an ice age would form a land bridge that even a cassowary could walk across (which is why cassowaries are shared with New Guinea).</p>
<p>For most other Australian birds found elsewhere, such as shorebirds and seabirds, water is no barrier.</p>
<p>But most of our birds are ours alone. Ours to enjoy and ours to care for – because they have no other home.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554674/original/file-20231019-17-q5axer.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A superb lyrebird (<em>Menura novaehollandiae</em>) in the Dandenong Ranges.</span>
<span class="attribution"><span class="source">Barry Baker</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/listen-to-the-alberts-lyrebird-the-best-performer-youve-never-heard-of-177627">Listen to the Albert’s lyrebird: the best performer you’ve never heard of</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/215809/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Garnett receives funding from the Australian Research Council. I am an active member of BirdLife Australia. </span></em></p>
Our birds are tough. They went through some mean climatic conditions to make Australia home.
Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/209067
2023-07-06T20:21:18Z
2023-07-06T20:21:18Z
Why are there hopping mice in Australia but no kangaroos in Asia? It’s a long story
<figure><img src="https://images.theconversation.com/files/535717/original/file-20230705-17-ey6m80.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C4467%2C3136&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The frill-necked lizard is one of many land animals that reached Australia from Southeast Asia.</span> <span class="attribution"><span class="source">Damien Esquerré</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The animals in Australia are super-different to those in Asia. This goes without saying; we know Australia is full of weird and wonderful creatures found nowhere else on Earth, such as the platypus and the koala. </p>
<p>But it may surprise you to know that many of our most iconic critters came from Asia and arrived only recently (in geological terms, at least).</p>
<p>These most recent members of Australia’s characteristic fauna include many lizards, such as goannas and thorny devils, and other animals including hopping mice, flying foxes and the kookaburra. Yet the traffic was largely one way – there are far fewer representatives of Australian fauna in Asia than there are Asian fauna in Australia.</p>
<p>Why is the situation so asymmetrical? In a <a href="https://doi.org/10.1126/science.adf7122">study</a> published today in the journal Science, my colleagues and I analysed information about the distribution and habitat of 20,433 species of land-dwelling vertebrates – as well as climate and plate tectonics over the past 30 million years – to find out.</p>
<h2>Drifting continents on a cooling planet</h2>
<p>The story begins more than 200 million years ago. </p>
<p>Dinosaurs were still a fairly new group walking the Earth, and Australia was part of a supercontinent called Gondwana. This giant landmass included modern Antarctica, South America, Africa, Australia and India. </p>
<p>Gondwana had just broken off from another supercontinent, called Laurasia, which was smooshed together from modern North America, Europe and Asia. The separation of Gondwana and Laurasia removed the last land connection between Australia and Asia.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the globe showing the supercontinents Gondwana and Laurasia." src="https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=581&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=581&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535940/original/file-20230705-21-j53okr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=581&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 supercontinents Gondwana and Laurasia before they separated over 200 million years ago.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Gondwana#/media/File:Laurasia-Gondwana.svg">Lennart Kudling / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Now, Gondwana itself began to fall part pretty shortly after separating from Laurasia. Each piece of Gondwana gradually became isolated and began its own independent journey. Many of these journeys led them back to Laurasia. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/breaking-new-ground-the-rise-of-plate-tectonics-7514">Breaking new ground – the rise of plate tectonics</a>
</strong>
</em>
</p>
<hr>
<p>India collided with Eurasia and formed the mighty Himalaya; South America crashed into North America, forming the snaking land bridge of Panama; Africa bumped into Eurasia, forming the Mediterranean Sea; and Australia began on a collision course with Asia.</p>
<p>Australia untethered its final Gondwanan connections between 45 and 35 million years ago, when it broke off from Antarctica. </p>
<p>At that time, Australia was much further south than it is today. As it drifted northwards, the increasing space between Australia and Antarctica kick-started the <a href="https://en.wikipedia.org/wiki/Antarctic_Circumpolar_Current">Antarctic circumpolar current</a>, which cooled the planet dramatically.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-the-antarctic-circumpolar-current-helps-keep-antarctica-frozen-106164">Explainer: how the Antarctic Circumpolar Current helps keep Antarctica frozen</a>
</strong>
</em>
</p>
<hr>
<p>Australia was isolated, cooling down and drying out. A unique set of animals and plants began to evolve.</p>
<h2>Intercontinental stepping stones</h2>
<p>Meanwhile, the Australian and Eurasian tectonic plates began to collide, forming thousands of islands in the Indonesian archipelago, including today’s Lombok, Sulawesi, Timor, and Lesser Sunda Isles.</p>
<p>These islands don’t belong to either the Australian continental shelf (also known as Sahul), which includes Australia and New Guinea, or to the Asian continental shelf (known as Sunda), which includes Thailand, Malaysia, Singapore, Sumatra, Java, Borneo, and Bali. </p>
<p>This in-between zone is known as Wallacea, after the 19th century British naturalist Alfred Russell Wallace. He first observed a difference in the types of animals found on either side of what is now called Wallace’s line.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of Indonesia, New Guinea and northern Australia with lines showing regions where different fauna live and climatic zones." src="https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535721/original/file-20230705-2760-7xl4ca.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">More animal species successfully made the crossing from Sunda to Sahul than the other way around.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1126/science.adf7122">Skeels et al. / Science</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The islands became stepping stones between two continents whose groups of species hadn’t seen each other in a very, very long time. But, as our new research shows, only particular kinds of animals were able to make the crossing and establish themselves on the other side.</p>
<h2>Wet and dry</h2>
<p>The first factor determining which animals spread between continents was their ability to cross the ocean. </p>
<p>Of all the groups of animals that moved between Asia and Australia, we found the staggering majority were birds. </p>
<p>But this wasn’t the only key to success. </p>
<figure class="align-center ">
<img alt="A photo of a kookaburra sitting on a wooden post with a beach in the background." src="https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535942/original/file-20230706-27-s5muy6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The great majority of animals that spread from Asia to Australia were birds – including the ancestors of the kookaburra.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Animals also needed to be able to thrive in their new location, where the environment may have been quite different. We found animals that could tolerate a broad range of wetter and drier environments were more likely to make the move successfully.</p>
<p>This makes sense. Sunda is wet and Sahul is dry, and if you can tolerate more of that wet–dry spectrum, you are better equipped to move between these regions.</p>
<p>But we still have a big question. Why did more animals move from Sunda to Sahul than in the other direction?</p>
<h2>A lot can change in 30 million years</h2>
<p>The final piece of the puzzle is considering how these crucial factors – the ability for species to disperse and establish themselves in new environments – have changed over time. </p>
<p>We know Sunda has been dominated by lush tropical rainforest since before Australia broke away from Antarctica. Later, when the stepping-stone islands began to pop up, they also had the kind of humid equatorial climate favoured by the rainforest vegetation, and later animals, from Sunda. </p>
<p>In Australia, however, similar rainforests were shrinking and being replaced by grasslands and woodlands in most areas.</p>
<figure class="align-center ">
<img alt="A photo of a kangaroo in the bush." src="https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535944/original/file-20230706-25-hte9mu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Marsupials such as the kangaroo spread widely across Sahul, but never made the leap across Wallace’s line to Sunda.</span>
<span class="attribution"><span class="source">Octavio Jiménez Robles</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>What this means is that as animals move from Sunda, through the stepping-stone islands, to New Guinea and the northern tips of Australia in Sahul, they experience a band of similar humid tropical climate. </p>
<p>However, most animals in Sahul evolved on the Australian mainland, most of which was much drier. So moving from mainland Australia, through New Guinea and the stepping stones, to Sunda, requires adaptations to a very different environment. </p>
<p>And Australian animals that did manage to make their way onto the stepping-stone islands would have likely met competition from Sunda groups already happily existing in their preferred tropical climate.</p>
<h2>Answers are a long time in the making</h2>
<p>Climate and geography are some of the most important things that shape evolution and the distributions of different species. Taking the long view, deep into the past, helps us understand the world around us. </p>
<p>Simple questions – like “why are there no kangaroos in Asia but hopping mice in Australia?” – have answers that are hundreds of millions of years in the making.</p><img src="https://counter.theconversation.com/content/209067/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Skeels does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
There’s no single reason many Asian animals spread to Australia but few went the other way – but climate, geography and the slow drift of tectonic plates all played a role.
Alexander Skeels, Postdoctoral Researcher, Macroevolution and Macroecology Group, Australian National 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>
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<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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<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>
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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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<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>
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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/194263
2022-11-22T13:28:52Z
2022-11-22T13:28:52Z
Exquisite new fossils from South Africa offer a glimpse into a thriving ecosystem 266 million years ago
<figure><img src="https://images.theconversation.com/files/494820/original/file-20221111-12-ata08h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fossilised insect wing with some of its colouration preserved is just one tiny treasure emerging from the site.</span> <span class="attribution"><span class="source">Rose Prevec</span></span></figcaption></figure><p>South Africa is famous for its amazingly <a href="https://onlinelibrary.wiley.com/doi/10.1002/9781118584538.ieba0461">rich and diverse fossil record</a>. The country’s rocks document more than 3.5 billion years of life on Earth: ancient forms of bacterial life, the emergence of life onto land, the evolution of seed-producing plants, reptiles, dinosaurs and mammals – and humanity.</p>
<p>Many will be familiar with hominid fossils such as the <em>Australopithecus africanus</em> skull Mrs (<a href="https://theconversation.com/one-of-the-worlds-most-famous-fossil-skulls-mrs-ples-is-actually-a-mr-90964">or is it Mr?</a>) Ples and the paradigm-shifting <a href="https://www.britannica.com/topic/Taung-child">Taung child</a>. Less well known and equally important fossils such as the oldest terrestrial vertebrates in the ancient supercontinent <a href="https://www.britannica.com/place/Gondwana-supercontinent">Gondwana</a>, which document the first steps from the ocean and <a href="https://phys.org/news/2013-09-oldest-gondwana-creature.html">onto land</a>, have also emerged from South Africa. The country’s wealth of fossils is due in part to the region’s unique geology, which documents 100 million years of nearly continuous deposition in its <a href="https://theconversation.com/why-south-africas-karoo-is-a-palaeontological-wonderland-43045">Karoo Basin</a>. </p>
<p>Fossils also hold clues to climatic shifts, from the great <a href="https://www.nationalgeographic.com/science/article/carboniferous">Carboniferous ice age</a> over 300 million years ago, to the huge dunes of blazing Jurassic deserts where dinosaurs <a href="https://doi.org/10.17159/sajs.2021/9145">roamed 200 million years ago</a>. Scientists can read the devastation of the <a href="https://theconversation.com/new-analysis-sheds-important-light-on-an-ancient-mass-extinction-event-132105">mass extinction events</a> that destroyed global ecosystems and changed the course of Earth’s history.</p>
<p>But in the race to understand the “big picture” of the evolution of life and to distil its dramatic ups and downs into punchy headlines, it is easy to forget the small and quiet things. Pause, and consider what life looked like on an average day, in a world without humans, mammals, birds, butterflies, flowers, or even dinosaurs. What was it like on the shores of a rippling lake, on a drowsy summer afternoon, 266 million years ago in what’s now the Northern Cape province of South Africa?</p>
<h2>The search, and what we found</h2>
<p>In a <a href="https://www.nature.com/articles/s42003-022-04132-y">new paper</a>, my colleagues and I provide the first glimpse of such an ecosystem. We have found a profusion of fossils of tiny insects that have never been found before, as well as important plant specimens that are changing our understanding of how they evolved. </p>
<p>Our findings give fresh insights into the effects of extinction events on ecosystems. The subject has taken on great urgency in the face of what scientists are calling the <a href="https://www.theguardian.com/environment/2017/jul/10/earths-sixth-mass-extinction-event-already-underway-scientists-warn">sixth great extinction event</a>, which is being driven by the current trend of global warming.</p>
<p>For the past few years we have been excavating a small, nondescript rock outcrop near Sutherland in the Northern Cape. </p>
<p>This outcrop is yielding untold fossil treasures of plants, insects and other invertebrates that are new to science. These unique fossils, some only a few millimetres long, are telling us about what lived in and around a calm pool on a delta plain during the middle Permian period between 266 million and 268 million years ago. Rocks of this age contain fossils of the oldest therapsids, a group of reptiles that eventually gave rise to the mammals. </p>
<p>Other life of this time included the lizard-like ancestors of tortoises, large amphibians that lurked like crocodiles just below the water surface, and forests dominated by a tree called <em>Glossopteris</em> with an understorey of spore-producing plants such as mosses, ferns and horsetails.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plant-fossils-have-a-lot-to-teach-us-about-earths-history-91014">Plant fossils have a lot to teach us about Earth's history</a>
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<p>Teams of palaeontologists have discovered and excavated many hundreds of vertebrate fossils in the western and southern Karoo of South Africa that date back to the Permian, including the <a href="https://www.frontiersin.org/articles/10.3389/feart.2021.631198/full">Sutherland District and surrounding areas</a>. But the kinds of rocks that are rich in vertebrate fossil bones tend not to preserve plants and invertebrates. These seem to require the more anoxic, acidic conditions present in calm lakes and pools for high fidelity preservation, whereas bones preserve well in more oxygen-rich settings. </p>
<p>This makes it difficult to understand the ecosystems of this time – and means our discoveries are especially astonishing. These include the oldest freshwater leech, a record that pushes back the known range of this group by 40 million years, and the oldest water mites by 166 million years.</p>
<p>Other exciting finds include the oldest damsel-fly and oldest stoneflies from Gondwana, as well as a profusion of the tiny, aquatic, immature stages (nymphs) of an extinct group called the <a href="http://palaeos.com/metazoa/arthropoda/palaeodictyopteroida/palaeodictyopteroida.html"><em>Palaeodictyoptera</em></a>. Many of the insect wings we have found have yet to be identified.</p>
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<img alt="" src="https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=571&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=571&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494821/original/file-20221111-14-ata08h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=571&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">A fossil of an insect nymph - so tiny that it is dwarfed by a human hand - and, on the right, seen under a microscope.</span>
<span class="attribution"><span class="source">Rose Prevec</span></span>
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<p>There are also mosses and liverworts, tiny soft plants that were among the first to colonise land. They too, have a very poor fossil record, and we have found both at our site. The liverwort is the oldest in Africa and one of only a few records for the Permian period globally. </p>
<p>One of the most exciting finds is the dense accumulations of the male and female cones of the <em>Glossopteris</em> plant, an unbelievably rare occurrence that is shedding light on the evolution and classification of this important coal-forming plant. </p>
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<img alt="" src="https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494825/original/file-20221111-23-yptw2n.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">Male and female cones of the Glossopteris plant.</span>
<span class="attribution"><span class="source">Rose Prevec</span></span>
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<h2>Great potential</h2>
<p>Our work has been slow. Excavations have involved a lot of sitting on spiky rocks in the sun for weeks on end, extracting tiny pieces of mudrock and then examining them with a magnifying hand lens. </p>
<p>The fossil site is still producing new weird and wonderful plants and invertebrates, and will keep us busy for a while. There is also great potential for finding other sites in the region. The thousands of plants and insects we have collected so far are being carefully curated and studied at the Albany Museum in Makhanda. We are keenly aware of the need to conserve this precious part of South Africa’s protected natural heritage. </p>
<p>Our work to better understand the organisms we’re finding provides knowledge about how and when they evolved and interacted as well as about local climate, how their distributions changed through time, how the positions of the continents changed, and the effects of deserts, mountain ranges and seas on the movement and evolution of life.</p>
<p>This is very important when trying to understand extinction events such as the <a href="https://www.nationalgeographic.com/science/article/permian-extinction">Great Dying</a>, which marked the end of the Permian 252 million years ago. It destroyed most life in the oceans and on land and – in a chilling echo of the <a href="https://theconversation.com/africa/topics/cop27-113638">current global climate crisis</a> – was driven by hundreds of thousands of years of volcanic activity that produced huge amounts of greenhouse gases, leading to an increase in global temperatures.</p><img src="https://counter.theconversation.com/content/194263/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rosemary Prevec receives funding from the National Research Foundation (NRF), and GENUS (DST-NRF Centre of Excellence in Palaeosciences).</span></em></p>
Tiny plant and insect fossils provide unique insight into an ancient ecosystem that would, later, be altered by climatic shifts.
Rosemary Prevec, Palaeontologist, Rhodes University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/191080
2022-09-29T20:04:30Z
2022-09-29T20:04:30Z
Let’s show a bit of love for the lillipilly. This humble plant forms the world’s largest genus of trees – and should be an Australian icon
<figure><img src="https://images.theconversation.com/files/487088/original/file-20220928-17-90tsrf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5991%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock </span></span></figcaption></figure><p>You’re probably familiar with the sight of a lillipilly bush. This hardy Australian staple – a glossy evergreen bearing powder-puff flowers and clusters of bright berries – features in many a garden hedge. </p>
<p>But you may not know this humble native has spread across the globe in waves of emigration, adaptation and evolution. Almost 1,200 species of lillipilly are now found in rainforests across the tropics and subtropics of Africa, Asia and the Pacific. </p>
<p>Our <a href="https://www.nature.com/articles/s41467-022-32637-x">research</a> helped reconstruct the evolutionary history of lillipillies in unprecedented detail. We show how lillipillies evolved in Australia and now form the largest genus of trees in the world. </p>
<p>Lillipillies are one of Australia’s great gifts to the natural world. But the story of these homegrown heroes may be taking a grim turn.</p>
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<img alt="bright magenta berries on green bush" src="https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487089/original/file-20220928-24-1o1saa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&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">Show off: the lillipilly is a glossy evergreen bearing clusters of bright berries.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>A plant on the move</h2>
<p>Lillipillies began their international adventures about 17 million years ago. At that time, the Australian continent (which together with New Guinea is known as the Sahul Shelf) was colliding with Southeast Asia (known as the Sunda Shelf) following its breakup with Antarctica. This breakup was the final dramatic act of the fragmentation of Gondwana. </p>
<p>The collision provided opportunity for biotic exchange between the northern and southern hemispheres. Many plants and animals moved south to the Sahul Shelf and prospered in the new lands. Lillipillies are one of the few lineages that moved in the other direction.</p>
<p>Along with our <a href="https://theconversation.com/how-songbirds-island-hopped-their-way-from-australia-to-colonise-the-world-64616">songbirds</a>, lillipillies stand as a rare example of an Australian group that set out from these shores and achieved major evolutionary success abroad. </p>
<figure class="align-right ">
<img alt="buttefly sits on flower" src="https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=479&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=479&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=479&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=602&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=602&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487090/original/file-20220928-22-29ync8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=602&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lillipillies are a magnet for pollinators.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Lillipillies light up our lives when they flower and fruit. Their showy white, cream or red flowers are followed by succulent red or purple berries. They’re a magnet for pollinators, helping fill our gardens with the songs of insects and birds. </p>
<p>The riberry, <em>Syzygium luehmannii</em>, is one of the most commonly grown and stunning garden species. It produces heavy crops of delicious fruit <a href="https://doi.org/10.1016/j.ifset.2007.03.007">rich in antioxidants</a> and prized by chefs. </p>
<p>Many species in the genus are used as food and medicine by Indigenous people, and <a href="https://phcogcommn.org/article/873">potent antibacterials</a> have been identified in the leaves of some species. Cloves, a favourite spice of home bakers, are the dried flower buds of an Indonesian lillipilly – the aptly named <em>Syzygium aromaticum</em>. </p>
<p>About <a href="https://biodiversity.org.au/nsl/services/search/taxonomy?product=APC&tree.id=51209179&name=Syzygium&inc._scientific=&inc.scientific=on&inc._cultivar=&max=100&display=apc&search=true">75 species</a> of lillipilly are native to all Australian states and territories except South Australia and Tasmania. </p>
<p>The greatest concentration of species is in the Wet Tropics World Heritage Area of northeast Queensland. <a href="https://apps.lucidcentral.org/rainforest/text/entities/search.htm?zoom_query=Syzygium">About 50</a> species are found there, half of which occur nowhere else on Earth. </p>
<p>And almost 1,200 species of lillipilly are now found in rainforests across the tropics and subtropics of Africa, Asia and the Pacific, including Australia.</p>
<p>As is common in the tropics, species new to science are regularly discovered and named. For example, <a href="https://www.ingentaconnect.com/content/nhn/blumea/2021/00000066/00000001/art00003">almost 30 new species</a> of lillipilly have been named from New Guinea in the last two years – and many more are likely awaiting scientific discovery.</p>
<p>But how did lillipillies achieve such international success? Our research team decided to find out. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-noisy-miners-to-be-less-despotic-think-twice-before-filling-your-garden-with-nectar-rich-flowers-190226">Want noisy miners to be less despotic? Think twice before filling your garden with nectar-rich flowers</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="yellow flowers on green bush" src="https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487092/original/file-20220928-12-h323i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The powder-puff flowers of lillipillies light up our lives when they flower.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Peering into the past</h2>
<p>The <a href="https://www.nature.com/articles/s41467-022-32637-x">research</a>, led by colleagues in Singapore, involved analysing the genomes of hundreds of living species of lillipillies.</p>
<p>Similarities and differences in the structure of genomes can reveal how closely related the species are. Using that knowledge, we can build up a picture of their genealogy - the “family tree” that connects ancestral species and their descendants. </p>
<p>These techniques also allow us to estimate the amount of genetic change that has occurred along the branches of the genealogy. And, if we’re lucky enough to have an accurately dated fossil of an ancestral species – as we do for lillipillies – we can calculate the rate of genetic change even more accurately.</p>
<p>All this allowed us to peer deeply into the past and reveal the events that set the lillipillies on their global journey.</p>
<p>We already knew lillipillies <a href="http://www.sciencedirect.com/science/article/pii/S1055790315002110">evolved</a> in Australia and emigrated into the rainforests of Africa, Asia and the Pacific. Our research showed this dispersion occurred in at least a dozen distinct waves. </p>
<p>Each emigrant lineage diversified rapidly and successfully in its new environment. This resulted in the nearly 1,200 lillipilly species found worldwide today – more than any other tree genus. In contrast, their relatives the eucalypts have largely remained only a local success story. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-50-beautiful-australian-plants-at-greatest-risk-of-extinction-and-how-to-save-them-160362">The 50 beautiful Australian plants at greatest risk of extinction — and how to save them</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="dirt road winds through stand of eucalypts" src="https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487095/original/file-20220928-6110-ku3e59.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">Australia’s eucalypts haven’t conquered the world as lillipillies have.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>A sad twist?</h2>
<p>Lillipillies may be one of Australia’s most successful botanical exports, but their future, like that of many rainforest plants globally, is threatened by habitat degradation and climate change.</p>
<p>The Magenta Cherry (<em>Syzygium paniculatum</em>), for example, is <a href="https://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10794">endangered</a> by coastal development in New South Wales. And the Brotherly Love Lillipilly (<em>Syzygium fratris</em>), found only on Queensland’s highest mountain, is <a href="https://www.sciencedirect.com/science/article/abs/pii/S000632071530029X">highly vulnerable</a> to climate change.</p>
<figure class="align-right ">
<img alt="yellow fungus on green leaves" src="https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487099/original/file-20220928-16-qwyz7.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">Myrtle rust – seen here on lillypilly leaves – may be the most potent threat of all.</span>
<span class="attribution"><span class="source">Wikimedia</span></span>
</figcaption>
</figure>
<p>But a devastating disease – myrtle rust - may be the most potent threat of all. It’s caused by an introduced fungal pathogen and kills new foliage, flowers and fruits of plants in the family Myrtaceae, to which lillipillies belong.</p>
<p>Myrtle rust arrived in Australia in 2010 and spread rapidly in the wind and via human activity. Already, it threatens <a href="https://www.apbsf.org.au/wp-content/uploads/2020/07/PBSF-Myrtle-Rust-National-Action-Plan-2020.pdf">some plant species</a> with extinction. Lillipilly species have been damaged by this serious disease, though none are under immediate extinction threat yet. </p>
<p>Lillipillies are an Australian origin story. They’re a major contributor to rainforest biodiversity and important to Indigenous cultures. And they’ve endeared themselves to generations of gardeners and cooks. </p>
<p>Given all this, lillipillies deserve to be recognised – and protected – as Aussie icons.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-threatens-up-to-100-of-trees-in-australian-cities-and-most-urban-species-worldwide-188807">Climate change threatens up to 100% of trees in Australian cities, and most urban species worldwide</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/191080/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Darren Crayn receives funding from the Australian Government and the Queensland Government. </span></em></p><p class="fine-print"><em><span>Stuart Worboys receives funding from the Ian Potter Foundation. This grant sponsored the collecting field work which contributed to this paper.</span></em></p>
Lillipillies are one of Australia’s great gifts to the natural world. But the story of these homegrown heroes may be taking a grim turn.
Darren Crayn, Professor and Director, Australian Tropical Herbarium, James Cook University
Stuart Worboys, Laboratory and Technical Support Officer, Australian Tropical Herbarium, James Cook University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/182600
2022-08-10T01:39:36Z
2022-08-10T01:39:36Z
Southern conifers: meet this vast group of ancient trees with mysteries still unsolved
<figure><img src="https://images.theconversation.com/files/477591/original/file-20220804-11072-3lt2g7.jpg?ixlib=rb-1.1.0&rect=0%2C20%2C3450%2C2276&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Huon pine in Tasmania</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>When you think of “conifers”, tall, conical shaped trees often found in public parks or front yards may spring to mind. But these impressive trees are far more fascinating than you may have realised, as they represent just one piece of an unsolved botanical puzzle.</p>
<p>These popular garden trees are from the northern hemisphere. But we also have conifers in the southern hemisphere, called “southern conifers”, found largely in Australia, South America, New Zealand and New Caledonia. </p>
<p>A little detective work reveals that southern conifers <a href="https://www.jstor.org/stable/2678646">evolved in Gondwana</a>, and long ago separated from coniferous relatives in the northern hemisphere. </p>
<p>They appeared around 200 million years ago, before the first flowering plants evolved, sharing land with the dinosaurs. One example is the Wollemi pine, which was famously saved in a <a href="https://www.abc.net.au/news/2020-05-27/bushfire-royal-commission-summer-ecological-disaster-wildlife/12290454">secret firefighting operation</a> during the 2019-2020 bushfires.</p>
<p>Unlike the introduced conifer garden trees, southern conifers are neither as well-known nor as popular with Australians as they should be. So let me help you get to know them a little better.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477587/original/file-20220804-25-1l2iml.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">These conical trees may be what spring to mind when you think of ‘conifer’</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Famous ‘living fossils’</h2>
<p>Northern conifers are mostly evergreen, woody trees with needle-like leaves, while southern conifers tend to have broad leaves like flowering trees. </p>
<p>Trees in the genus <em>Araucaria</em>, including the monkey puzzle, bunya bunya, hoop pine and Norfolk Island pine, are southern conifers. As are most members of the Podocarp family (Huon pine, celery top pine and plum pine) and 22 species of <em>Agathis</em> (including the majestic Queensland and New Zealand Kauri trees).</p>
<p>Southern conifers often possess cones, such as the <em>Araucaria</em> and <em>Agathis</em> species. Sometimes, these cones are very large and heavy that can cause serious injury if they fall from high in the tree onto an unsuspecting passerby. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/backyard-gardeners-around-the-world-are-helping-to-save-australias-deeply-ancient-wollemi-pine-138797">Backyard gardeners around the world are helping to save Australia's deeply ancient Wollemi pine</a>
</strong>
</em>
</p>
<hr>
<p>Some southern conifers can be over 30 metres high. Others, such as the Kauri and Huon pine, are renowned for <a href="https://www.publish.csiro.au/bt/bt98093">their longevity</a>. They can live for centuries or, for the Huon pine, perhaps over an astonishing <a href="https://theconversation.com/where-the-old-things-are-australias-most-ancient-trees-65893">ten millennia</a>. </p>
<p>While all species of southern conifers are of ancient origin, the <a href="http://www.wollemipine.com/">Wollemi pine</a> is famous for its status as a “living fossil”. Of course, this is a contradiction in terms – a fossil is any evidence of past life. </p>
<p>But in this context, the term refers to organisms that appeared in the fossil record long ago, were then thought to be extinct, before a living version was discovered. We are curious as to how they successfully hid for so long and may imagine a link with a distant, different past. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&rect=0%2C18%2C2048%2C1342&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&rect=0%2C18%2C2048%2C1342&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477584/original/file-20220804-18-rwmbrn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Monkey Puzzle tree, <em>Araucaria Araucana</em></span>
<span class="attribution"><span class="source">Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>So, the question botanists have yet to answer is: how distant are the north and south relatives?</p>
<h2>When flowering plants evolved</h2>
<p>Many southern conifers show little resemblance to the “true conifers” of the northern hemisphere, such as pine, cedar, spruce and juniper. </p>
<p>All conifers are gymnosperms, which means they have naked seeds and cones. They evolved from an ancient group of seed ferns, before the fragmentation of the super continent Pangaea. </p>
<p>These seed ferns were a diverse group. As Pangaea divided into Gondwana in the south and Laurasia in the north, the seed ferns began to diversify, giving rise to northern and southern seed ferns. </p>
<p>Botanists have long known that northern conifers and other gymnosperms <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/araucariaceae">evolved</a> from these northern seed ferns. But what of the southern seed ferns? They remained a bit of a mystery until the 1970s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477593/original/file-20220804-16-bleryo.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">Cones of a spruce tree.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>One group of southern seed ferns constituted what’s <a href="https://www.sciencedirect.com/science/article/abs/pii/S1342937X15000490">now called</a> the Glossopteris flora, which was of Gondwanan origin. From this diverse group of Glossopterids, flowering plants in all their variety evolved. </p>
<p>This solved one of the great riddles of botany – the origin of the flowering plants which had puzzled scientists, particularly in the northern hemisphere until the early 1980s.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/where-the-old-things-are-australias-most-ancient-trees-65893">Where the old things are: Australia's most ancient trees</a>
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</em>
</p>
<hr>
<p>It’s likely southern conifers also evolved from these southern seed ferns. Some may have arisen from other members of the Glossopteris group, too, or perhaps their relatives. </p>
<p>If this was the case, then the southern conifers would be more closely related to flowering plants than to the true conifers of the north. </p>
<h2>When the trees were in fashion</h2>
<p>After millions of years of evolution, southern conifers became fashionable with gardeners <a href="https://www.theguardian.com/lifeandstyle/gardening-blog/2015/may/07/monkey-puzzles-araucaria">in the 1800s</a>.</p>
<p>Their novelty and striking form captured the interest of the educated and wealthy landowners of Europe and they were planted as status symbols on estates and in public gardens. </p>
<p>In Australia they were planted in large private gardens and in many public parks from the mid 1800s to World War 1, after which their popularity waned.</p>
<p>You can see many of these fine trees growing still in large gardens and public parks across Australia, such as botanic gardens in most Australian states, as well as in smaller public parks and gardens of older suburbs and inland towns. Their striking, almost geometrical, form catches the eye. </p>
<p>Southern conifers are known for their resilience, are rarely affected by pests or disease and, despite their large size, cause few problems with paths, roads, buildings and other urban infrastructure. Probably because they were given plenty of space to grow when first planted.</p>
<h2>We still have much to learn</h2>
<p>It takes time to solve some of these botanical puzzles. Evolution is a sophisticated process that has led to very complex relationships between plant groups. </p>
<p>In future we may well recognise that southern conifers are not really conifers at all. Perhaps, the links between the two groups go so far back in time, the relationship is too distant for both southern and true conifers to be called conifers at all.</p>
<p>In any case, these mysterious trees have persisted through <a href="https://www.jstor.org/stable/2678646">vast periods of time</a> and changing environments – they have much to teach us about plant responses to climate change.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dinosaur-food-and-hiroshima-bomb-survivors-maidenhair-trees-are-living-fossils-and-your-new-favourite-plant-164630">Dinosaur food and Hiroshima bomb survivors: maidenhair trees are 'living fossils' and your new favourite plant</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/182600/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Moore 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>
Some of these trees can be over 30 metres high. Others, can live for centuries or, for the Huon pine, up to an astonishing ten millennia.
Gregory Moore, Senior Research Associate, School of Ecosystem and Forest Sciences, The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/175317
2022-03-28T05:44:25Z
2022-03-28T05:44:25Z
Hidden away in a museum, we found the skull of a rare armoured dinosaur that roamed Queensland 105 million years ago
<figure><img src="https://images.theconversation.com/files/450544/original/file-20220307-126102-1xbnuoz.jpg?ixlib=rb-1.1.0&rect=21%2C21%2C3591%2C2465&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>You might think all important dinosaur “discoveries” are made as soon as fossils are collected in the field – that palaeontologists instantly know the significance of what they’ve found.</p>
<p>This is often true. But sometimes, and maybe more often than you’d think, fossils will be stored in museum collections for years before the right researchers come along to “rediscover” them. This was the case for one Australian ankylosaur skull, which we’ve <a href="https://www.frontiersin.org/articles/10.3389/feart.2022.803505/full">published about</a> today in the journal Frontiers in Earth Sciences.</p>
<p>Originally discovered in 2005 near the regional Queensland town of Boulia, the specimen remained at the South Australian Museum until we enquired about the museum’s dinosaur collection.</p>
<p>Ankylosaurs, the so-called “armoured” dinosaurs, are a group of dinosaurs that lived from the Early Jurassic to the Late Cretaceous – roughly 196 to 66 million years ago.</p>
<p>Compared to other dinosaurs, such as the <a href="https://theconversation.com/introducing-australotitan-australias-largest-dinosaur-yet-spanned-the-length-of-2-buses-162177">long-necked sauropods</a> and smaller herbivorous <a href="https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1564757">ornithopods</a>, ankylosaur remains are rarely found in Australia and the broader southern hemisphere. So you can imagine our excitement when we “rediscovered” Australia’s second ankylosaur skull. </p>
<p>An analysis of the skull bones and teeth suggests it belongs to the genus <a href="https://peerj.com/articles/1475/"><em>Kunbarrasaurus</em></a>, which also contains the first Australian ankylosaur skull.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/introducing-australotitan-australias-largest-dinosaur-yet-spanned-the-length-of-2-buses-162177">Introducing Australotitan: Australia's largest dinosaur yet spanned the length of 2 buses</a>
</strong>
</em>
</p>
<hr>
<h2>What were ankylosaurs like?</h2>
<p>Ankylosaurs were medium-to-giant herbivorous dinosaurs (anywhere between 200-5,000kg) that walked on four legs and were covered in armoured plates or spikes. Some are recognisable by tail clubs, such as the five-tonne <em>Ankylosaurus magniventris</em> from North America.</p>
<p>Of the 75 <a href="https://paleobiodb.org/">recognised</a> ankylosaur species, only five are from the southern hemisphere. Several small and incomplete fossils are spattered across the ancient Gondwana supercontinent – which is now dispersed and broken up into Australia, India (which back then was in the southern hemisphere), Africa, Antarctica and South America. </p>
<p>These fossils offer tantalising hints of what was once a widespread ankylosaur presence in these regions. The five Gondwanan ankylosaur species are <em>Kunbarrasaurus ieversi</em> and <em>Minmi paravertebra</em> from Australia, <em>Antarctopelta oliveroi</em> from Antarctica, <em>Spicomellus afer</em> from Africa, and <em>Stegorous elengassen</em> from Chile. </p>
<h2>A dinosaur from Boulia</h2>
<p>The bones of the ankylosaur from Boulia were found encased in a large, hard rock called a <a href="https://geokansas.ku.edu/concretion">concretion</a>. Concretions often form around organic matter, and likely helped the initial preservation of the fossil. When it was discovered, all that was visible was a series of rock chunks that could have easily been overlooked. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/448774/original/file-20220228-95421-1w371cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Boulia ankylosaur was excavated from the Warra station in 2005. (Block in the bottom left contains ankylosaur limb bones)</span>
<span class="attribution"><span class="source">Benjamin Kear (Uppsala University)</span></span>
</figcaption>
</figure>
<p>The collected fossils include limbs, vertebrae, many armoured plates and, excitingly, a partial skull. Along with several skull bones, the skull also includes the impressions of many teeth from the upper jaw. </p>
<p>The entire skull block was scanned at the Australian Synchrotron in Melbourne. The synchrotron shoots x-rays at the specimen, generating a series of images that can be processed to reveal the bones in 3D (as seen below). </p>
<iframe src="https://une.pedestal3d.com/r/K-iBggKkmP?sidebar=closed" width="100%" height="600px"></iframe>
<p>This technique is often used for fossils that may otherwise get damaged or lose important information if physically removed from the rock.</p>
<p>We analysed the scans and discovered the bones are those of the roof of the mouth (or the palate). We also found several teeth “floating” within the block.</p>
<h2>Placing southern ankylosaurs in the family tree</h2>
<p>Identifying this new ankylosaur as <em>Kunbarrasaurus</em> suggests this particular dinosaur was potentially more widespread in Queensland than previously thought, and may have existed for more than five million years. But what do ankylosaurs from Australia, and Gondwana more generally, tell us about the group’s evolution as a whole?</p>
<p>As it stands, the vast majority of ankylosaurs are from either North America, Europe, or Asia. And most are from the late Cretaceous (100 to 66 million years ago). However our study suggests a separate and possibly earlier diversity of ankylosaurs in the south, a theory which is supported by recent discoveries from <a href="https://www.abc.net.au/news/2021-12-02/dinosaur-has-resemblance-to-aztec-weapon/100667992">South America</a> and <a href="https://www.nhm.ac.uk/discover/news/2021/september/new-species-of-dinosaur-had-armour-unlike-anything-seen-before.html">Africa</a>.</p>
<p>The southern radiation of ankylosaurs includes the species from Australia, Chile and Antarctica, all of which together form the group called <a href="https://www.nature.com/articles/d41586-021-03572-6">Parankylosauria</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/448777/original/file-20220228-95421-1p3j8px.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A reconstruction of <em>Kunbarrrasaurus ieversi</em> from Richmond, Queensland.</span>
<span class="attribution"><span class="source">Australian Geographic</span></span>
</figcaption>
</figure>
<h2>The importance of the Boulia ankylosaur</h2>
<p>Because the fossil block was scanned with x-rays and reconstructed in 3D, we were able to explore aspects of the ankylosaur’s airways, or “choanae”. These were not well preserved in the first and only other known <em>Kunbarrasaurus</em> skull.</p>
<p>Typically ankylosaur choanae are long, located close to the front of the snout and can have multiple openings within the palate. Coupled with complex nasal passages, these features point to the group generally having a keen sense of smell.</p>
<p>However, in the Boulia ankylosaur there is only one opening on each side, and they are located towards the back of the palate. This suggests <em>Kunbarrasaurus</em> did not have the complex nasal system seen in ankylosaurs such as <em><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0150845">Pawpawsaurus campbelli</a></em> and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207381"><em>Euplocephalus tutus</em></a>. As such, it may have had a reduced sense of smell compared to most of its northern counterparts. </p>
<p>There is still a lot we don’t know about ankylosaur evolution, especially the Gondwanan species. Perhaps more of these discoveries await us in museum troves.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dinosaurs-were-already-in-decline-before-the-asteroid-wiped-them-out-new-research-163624">Dinosaurs were already in decline before the asteroid wiped them out – new research</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/175317/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicolas Campione receives funding from Australian Research Council. </span></em></p><p class="fine-print"><em><span>Phil Bell received funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Timothy Frauenfelder 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>
An analysis of the skull suggests the ankylosaur may have had a poorer sense of smell than its counterparts in the northern hemisphere.
Timothy Frauenfelder, PhD Candidate in Palaeontology, University of New England
Nicolas Campione, Senior lecturer, University of New England
Phil Bell, Palaeontologist, Earth Science Faculty, University of New England
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/164630
2022-01-20T19:04:45Z
2022-01-20T19:04:45Z
Dinosaur food and Hiroshima bomb survivors: maidenhair trees are ‘living fossils’ and your new favourite plant
<figure><img src="https://images.theconversation.com/files/440755/original/file-20220113-27-1n973ig.jpg?ixlib=rb-1.1.0&rect=0%2C16%2C5416%2C3583&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Zhang Kaiyv/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Most of us are captivated by the thought of a “living fossil”, which is any organism that appeared millions of years ago in the fossil record and survives today, relatively unchanged.</p>
<p>The maidenhair tree, <em>Ginkgo biloba</em>, ticks all the boxes of this definition. The genus <em>Ginkgo</em> is well known in China and Japan where it has special significance in Buddhism and Confucianism, and first became known to European botanists in the <a href="https://e360.yale.edu/features/peter_crane_history_of_ginkgo_earths_oldest_tree">late 1600s</a>. </p>
<p>Today, ancient ginkgo fossils can be found all over the world, some of which are almost 300 million years old – a time when dinosaurs roamed the planet. Let’s delve further into what makes this species so remarkable: from its ability to survive nuclear bombs, to its vomit-smelling seeds, to it’s beautiful autumn display.</p>
<h2>Hardy survivors</h2>
<p>The ancestral ginkgo evolved so long ago it spread across the super continent Pangaea and was present in both the northern component (Laurasia) and the southern part (Gondwana, which included Australia) when the continents fragmented. </p>
<p><a href="http://www.fossilmuseum.net/plantfossils/Ginkgoites/Ginkgoites.htm">As a result</a> there are fossils, <em>Ginkgo australis</em>, from the cretaceous period about 65-140 million years ago in the Koonwarra Fish Fossil beds near Leongatha, Victoria. There are also much more recent (about 20 million years old) fossils from Tasmania.</p>
<p><em>Ginkgo biloba</em> has an intriguing appearance. It can grow up to 35 metres tall with a spreading canopy, and its leaves are a wonderful fan shape, often with a little cleft or notch. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440760/original/file-20220113-1519-1mak6c5.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">The wonderful fan shape of their leaves.</span>
<span class="attribution"><span class="source">Photoholgic/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>As you might imagine for a genus dating back almost 300 million years, the maidenhair tree is both hardy and resilient, tolerating a wide range of soil and climatic conditions. </p>
<p>The tree is known to be very long-lived and some specimens at temple sites are thought to be over 1,000 years old which, in part, explains <a href="https://www.abc.net.au/gardening/factsheets/maidenhair-tree/9436966">the mystique</a> associated with the species.</p>
<p>They have a lignotuber – a modified stem at the base of the trunk containing lots of buds – which allows for sprouting at ground level and multiple stems. The lignotuber allows for rapid recovery from serious environmental stresses such as fire and defoliation. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tree-ferns-are-older-than-dinosaurs-and-thats-not-even-the-most-interesting-thing-about-them-138435">Tree ferns are older than dinosaurs. And that's not even the most interesting thing about them</a>
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</em>
</p>
<hr>
<p>In fact, six trees <a href="https://www.academia.edu/1135523/Ginkgo_in_Australia">not only survived</a> the bombing of Hiroshima, but recovered quickly, are healthy and <a href="https://www.vox.com/the-highlight/2019/10/29/20932379/ginkgo-tree-atomic-bomb-hiroshima-bombing">growing still</a>. Their survival showed the resilience of the ginkgo and the trees became an <a href="https://www.bbc.com/news/uk-england-manchester-29920359">important symbol</a> that recovery from disaster was, indeed, possible. </p>
<p>Australians can empathise with this as the vibrant re-sprouting of trees after bushfires often plays a similar symbolic role.</p>
<h2>Stinky seeds and dinosaur food</h2>
<p>Things continue to get interesting when you consider there are separate male and female trees; a relatively rare feature in modern trees. The male reproductive structures have mobile sperm that swim to the ovule for fertilisation, which is considered a primitive or ancient characteristic.</p>
<p>If fertilisation occurs, the female tree produces a seed that resembles a fruit. The seed’s soft fleshy layer is malodorous, with people often describing it as being revolting or smelling of human vomit. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440761/original/file-20220113-21-1qb28wj.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">The seeds, resembling fruits, are known for its repulsive smell.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>A pair of female maidenhair trees was planted outside the entrance to the Old Geology building at the University of Melbourne in the 1920s. Since then, staff and students have had to use the side entrance when trees held seeds. This will probably continue for decades to come.</p>
<p>Likewise, I know of a couple of female trees that were planted outside the entrance to a major bank branch in Hawthorn, Victoria. It was considered karma by disgruntled customers, until their sudden removal by a desperate manager.</p>
<p>The male tree doesn’t smell but produces pollen, which has been known to cause allergies, so be wary of which sex you plant <a href="https://bie.ala.org.au/species/NZOR-6-74385">and where</a> you plant them. </p>
<p>The seed’s strong scent has been linked to its dispersal, as many animals are drawn to strong, even rancid smelling fruits. There’s little evidence as to which animals or birds eat ginkgo seeds today, but there has been speculation the seeds may have been eaten by dinosaurs. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/friday-essay-trees-have-many-stories-to-tell-is-this-our-last-chance-to-read-them-161428">Friday essay: trees have many stories to tell. Is this our last chance to read them?</a>
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</p>
<hr>
<p>Ginkgos <a href="http://blogs.nature.com/soapboxscience/2011/11/02/the-living-dinosaur">coexisted with dinosaurs</a> for millions of years. It’s easy to imagine a huge herbivorous dinosaur munching on tall maidenhair trees. Sadly, there’s no evidence of gingko seeds in fossilised dinosaur droppings. But for those who are captivated by the connection of a living fossil and dinosaurs, perhaps that fossil is still to be found. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440754/original/file-20220113-15-6llrxg.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"><em>Ginkgo biloba</em> in Huishan Temple of Huishan Ancient Town, China.</span>
<span class="attribution"><span class="source">Jerry Wang/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Ginkgo for gardeners</h2>
<p><em>Ginkgo biloba</em> has been cultivated for more than 3,000 years, and so whether it grows naturally in the wild is uncertain. Even in China, it grows most often in homes and temples, and there’s very little genetic diversity within the plants suggesting they’ve been grown from cuttings. </p>
<p>The tree has been so widely planted it now occurs in major cities and botanic gardens around the world. <a href="https://www.academia.edu/1135523/Ginkgo_in_Australia">In Australia</a>, many of us live within a few kilometres of a recent planting.</p>
<p>Many of the ginkgo trees planted in urban landscapes are males grown from cuttings. But there are different cultivars available from nurseries, with some being all female varieties that are highly prized for their brilliant yellow autumnal colour. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bright yellow Ginkgo tree" src="https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440751/original/file-20220113-1697-q978np.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female trees have a stunning autumn display.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Apart from allergenic pollen and vile smelling seeds, <em>Ginkgo biloba</em> can have another very annoying or perhaps frustrating habit for gardeners. Young plants can grow very tall before their side branches begin to grow and develop. This form of growth, called bolting, is considered an adaptation to stressed environments, but it’s little consolation when you’ve been growing a gingko for 20 years, it’s over 6m tall and still looks like a bean pole.</p>
<p>You have to be patient with slow-growing, long-lived trees, but they’re worth the wait! They rarely, if ever, have pest or disease problems, they are hardy and, despite being cultivated in Europe and North America for centuries, have never become weedy. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/running-out-of-things-to-do-in-isolation-get-back-in-the-garden-with-these-ideas-from-4-experts-134229">Running out of things to do in isolation? Get back in the garden with these ideas from 4 experts</a>
</strong>
</em>
</p>
<hr>
<p>They may well be described as living fossils, but they are in fact a resilient genus of modern plants that can cope with whatever the environment has thrown at them for over 300 million years. </p>
<p>They are the epitome of great survivors and I would not be betting against their chances of surviving for millennia to come.</p><img src="https://counter.theconversation.com/content/164630/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Moore 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>
Maidenhair trees, Ginkgo biloba, can live for over 1,000 years and grow 35m tall. While they’re beautiful to look at, they’re also notorious for their vomit-smelling seeds.
Gregory Moore, Doctor of Botany, The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/147576
2021-01-05T19:01:51Z
2021-01-05T19:01:51Z
Photos from the field: zooming in on Australia’s hidden world of exquisite mites, snails and beetles
<figure><img src="https://images.theconversation.com/files/377109/original/file-20210105-17-1wgn84n.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C1997%2C1320&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dragon springtails (pictured) are widely distributed in forests of eastern Australia — yet they're still largely unknown to science. </span> <span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span></figcaption></figure><p><em>Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this series, we’ve invited them to share their unique <a href="https://theconversation.com/au/topics/photos-from-the-field-92499">photos from the field</a>.</em></p>
<hr>
<p>Which animals are quintessentially Australian? Koalas and kangaroos, emus, tiger snakes and green tree frogs, echidnas and eastern rosellas, perhaps. And let’s not forget common wombats.</p>
<p>Inevitably, most lists will be biased to the more conspicuous mammals and birds, hold fewer reptiles and frogs, and likely lack invertebrates — animals without a backbone or bony skeleton — altogether. </p>
<p>I’m an <a href="https://twitter.com/InvertoPhiles">invertophile</a>, fascinated by our rich terrestrial invertebrate fauna, so my list will be different. I’m enchanted by stunning dragon springtails, by cryptic little <em>Tasmanitachoides</em> beetles, and by the poorly known allothyrid mites, among thousands of others.</p>
<p>Australia’s terrestrial invertebrate multitude contains several hundred thousand uniquely Australian organisms. Most remain poorly known. </p>
<p>To preserve our biodiversity, we first must ask: “which species live where?”. For our invertebrates, we are a long way from knowing even this.</p>
<h2>The Black Summer toll</h2>
<p>Last year, a team of scientists estimated that the Australian 2019-2020 bushfires killed, injured or displaced <a href="https://www.wwf.org.au/news/news/2020/3-billion-animals-impacted-by-australia-bushfire-crisis#gs.kcnvaj%22%22">three billion animals</a>. That was a lot. But it was also a woefully inadequate estimate, because it only accounted for mammals, reptiles, birds and frogs.</p>
<p>Hidden from view, many trillions more invertebrates burned or were displaced by the fires. And yes, invertebrates are animals too.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377110/original/file-20210105-13-9gzwrp.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">A mite from the family Bdellidae (on the right) has captured a springtail, and is using its piercing mouthparts to suck it dry. Mites and springtails are among the most abundant animals on the planet.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Admittedly, it’s <a href="https://theconversation.com/after-the-bushfires-we-helped-choose-the-animals-and-plants-in-most-need-heres-how-we-did-it-138736">hard to come to terms with invertebrates</a> because they’re often hard to find and difficult to identify. Most species are inconspicuous, even if they belong to incredibly abundant groups, such as mites and springtails, which can occur in numbers exceeding 10,000 per square metre.</p>
<p>Most invertebrates are poorly known because there are so many species and so few people working on them. In fact, it’s likely only a <a href="https://www.environment.gov.au/system/files/pages/2ee3f4a1-f130-465b-9c7a-79373680a067/files/nlsaw-2nd-complete.pdf">quarter to one-third</a> of Australia’s terrestrial invertebrate fauna is formally described (have a recognised scientific name). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A translucent land snail" src="https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377111/original/file-20210105-23-62kgis.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"><em>Meredithina dandenongensis</em>, a species from the wet forests of Victoria. It can be found during the day under rotting logs. The land snail family Charopidae contains hundreds of species across wetter parts of southern and eastern Australia.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>One of the problems invertebrates have, in terms of attracting attention, is that many are not easily seen with the naked eye. </p>
<p>Macrophotography can magnify these wonders for a view into a world most of us are completely unfamiliar with. Even then, it often will be hard to know what we see. Everyone will recognise a kangaroo, but who can identify an allothyrid mite?</p>
<p>The photo below shows an undescribed species of mite from the family <a href="https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:790b85ba-7f3c-41f3-b117-c5379c7fa4e5">Allothyridae</a>, from Mount Donna Buang in Victoria. The mite family Allothyridae has three described Australian species, and dozens more awaiting description.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377108/original/file-20210105-13-d0oe6d.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">An undescribed Allothyridae species. Just one of the many species in this group waiting to be studied.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This collage shows a selection of mites found in the forests of southeastern Australia. It’s likely many of the species shown here are unknown to science. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377107/original/file-20210105-19-yujey4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mites are a very ancient and diverse group. They can be found abundantly in most terrestrial habitats but are rarely seen because most are several millimetres long or smaller.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A deeply ancient lineage</h2>
<p>Animal ecologists, most of whom work on vertebrates, often joke that I “study the ‘food’, haha…”. They think they’re funny, but this reflects a deep seated bias — one <a href="https://www.penguin.com.au/books/animals-make-us-human-9781760899813">extending from scientists to the wider public</a>. This limits the development of a comprehensive understanding of biodiversity that has flow-on effects for conservation more broadly.</p>
<p>It’s true: invertebrates are food for larger animals. But their vital role in maintaining Australia’s ecosystems doesn’t end there. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1333360079706353666"}"></div></p>
<p>Every species has an evolutionary history, a particular habitat, a set of behaviours reflecting that history, and a role to play in the ecosystem. And many terrestrial invertebrates belong to especially ancient lineages that record the deep history of Australia’s past.</p>
<p>The moss bug family Peloridiidae, for example, dates back <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/cla.12237">more than 150 million years</a>. For context, the kangaroo family (Macropodidae) is likely 15-25 million years old.</p>
<p>Their history is reflected in the breakup of the ancient supercontinent, Gondwana. In fact, Australian species of moss bugs are more closely related to South American species than to those from nearby New Zealand. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bronze-coloured beetle with delicate, translucent wings" src="https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=357&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=357&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=357&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=448&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=448&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377127/original/file-20210105-15-1sqpyr2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=448&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>Chasoke</em> belongs to the beetle family Staphylinidae, which is currently considered the largest family of organisms on Earth, with more than 60,000 scientifically described species. Mt. Donna Buang, Victoria.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This is a common pattern in terrestrial invertebrate groups. It reflects how the New Zealand plate separated from the remainder of <a href="https://theconversation.com/australia-moving-on-up-from-down-under-7658">Gondwana</a> about 80 million years ago, while the Australian plate remained connected to South America via Antarctica.</p>
<p>Similar stories can be told from across the invertebrate spectrum. The photo below shows a few examples of these relics from Gondwana. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377101/original/file-20210105-17-1arjp53.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Peloridiid bugs — such as <em>Hemiodoecus leai</em> China, 1924 (top left) — are restricted to the wettest forests where they feed on moss. Top right: A new species of <em>Acropsopilio</em> (Acropsopilionidae) harvestman from the Dandenong Ranges. Bottom left: a new velvet worm from the Otway Ranges. Bottom right: <em>Tasmanitachoides hobarti</em> from Lake St Clair in central Tasmania.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Their fascinating evolution</h2>
<p>Overprinting this deep history are the changes that occurred in Australia, especially the <a href="https://australian.museum/learn/australia-over-time/evolving-landscape/the-late-miocene-epoch/">drying of the continent</a> since the middle Miocene, about 12-16 million years ago. </p>
<p>This continent-wide drying fragmented wet forests that covered much of the continent, resulting in the restriction of many invertebrate groups to pockets of wetter habitat, especially along the Great Dividing Range and in southwestern Australia.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/trapdoor-spider-species-that-stay-local-put-themselves-at-risk-114588">Trapdoor spider species that stay local put themselves at risk</a>
</strong>
</em>
</p>
<hr>
<p>A consequence of this was the evolution in isolation of many “<a href="https://theconversation.com/trapdoor-spider-species-that-stay-local-put-themselves-at-risk-114588">short-range endemic</a>” species.</p>
<p>A short-range endemic species means their geographic distribution is less than 10,000 square kilometres. A short-range endemic mammal you might be familiar with is Leadbeater’s possum, restricted to the wet forests of the Victorian Central Highlands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A long, brown and orange thrips with six legs." src="https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=382&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=382&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377130/original/file-20210105-19-bkzh68.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=382&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 is <em>Idolothrips spectrum</em>, the largest thrips in the world. It’s called the giant thrips, even though it’s less than 10mm long. Dandenong Ranges, Victoria.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But short-range endemism is much more common in invertebrates than other organisms. This is because many invertebrates are poor dispersers: they don’t move between habitat patches easily. They may also maintain viable populations in small areas of suitable habitat, and are frequently adapted to very specific habitats.</p>
<p>Take <em>Tropidotrechus</em>, pictured below, a genus of beetles mostly restricted to the same region as Leadbeater’s possum. They, however, divide the landscape at a much finer scale because they’re restricted to deep leaf litter in cool, wet, forest gullies. </p>
<p>As Australia dried, populations of <em>Tropidotrechus</em> became isolated in small patches of upland habitat, evolving into at least seven species across the ranges to the east of Melbourne.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377106/original/file-20210105-15-zd7ikc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=293&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>Tropidotrechus victoriae</em>, Victoria’s unofficial beetle emblem (left). Related described and undescribed species are found in the nearby Central Highlands and South Gippsland ranges (right)</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Discoveries waiting to happen</h2>
<p>The trouble with knowing so little about Australia’s extraordinary number of tiny, often locally unique invertebrates, is that we then massively underestimate how many of them are under threat, or have been badly hit by events like the 2019-2020 fires.</p>
<p>If we wish to conserve biodiversity widely, rather than only the larger charismatic wildlife, then enhancing our knowledge of our short-range species should be a high priority. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="One shiny green beetle on top of another" src="https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377129/original/file-20210105-19-wbedgc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You don’t necessarily need specialist equipment to take pictures of our fascinating invertebrates. This is a phone picture of mating <em>Repsimus</em> scarab beetles (relatives to the Christmas beetles). It was taken at Bemboka in NSW, which burnt during the 2019-2020 fires.</span>
<span class="attribution"><span class="source">Nick Porch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We’ve only just scratched the surface of Australia’s wonderful invertebrate fauna, so there are enough discoveries for everyone. </p>
<p>You can join <a href="https://www.inaturalist.org/home">iNaturalist</a>, a citizen science initiative that lets you upload images and identify your discoveries. Perhaps you’ll <a href="https://www.abc.net.au/news/2020-09-30/new-jumping-spider-found-in-nsw-backyard/12718220">discover something new</a> — and a scientist just might name it after you.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-teach-kids-about-nature-insects-can-help-145160">Want to teach kids about nature? Insects can help</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/147576/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nick Porch receives funding from the Australian Research Council, the Australian Nuclear Science and Technology Organisation, the Plomley Foundation, the Marsden Fund, National Geographic and the Wildlife and Habitat Bushfire Recovery Program (Department of Agriculture, Water and the Environment).</span></em></p>
Australia’s invertebrates have an ancient lineage and a fascinating evolution. Get up close with macrophotography to discover tiny, unique animals you’ve probably never seen before.
Nick Porch, Senior Lecturer in Environmental Earth Science, Deakin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/138434
2020-06-12T04:47:15Z
2020-06-12T04:47:15Z
The coastal banksia has its roots in ancient Gondwana
<figure><img src="https://images.theconversation.com/files/341052/original/file-20200611-114066-10q242f.jpg?ixlib=rb-1.1.0&rect=220%2C141%2C1493%2C833&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://flic.kr/p/ecVh2F">John Tann/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If you fondly remember May Gibbs’s <a href="https://maygibbs.org/story/gumnut-babies/">Gumnut Baby</a> stories about the adventures of Snugglepot and Cuddlepie, you may also remember the villainous <a href="https://maygibbs.org/characters/big-bad-banksia-men/">Big Bad Banksia Men</a> (perhaps you’re still having nightmares about them). </p>
<p>But banksias are nothing to be afraid of. They’re a marvellous group of Australian native trees and shrubs, with an ancient heritage and a vital role in Australian plant ecology, colonial history and bushfire regeneration.</p>
<p>The <a href="https://www.anbg.gov.au/banksia/">genus Banksia</a> has about 173 native species. It takes its name from botanist <a href="https://theconversation.com/botany-and-the-colonisation-of-australia-in-1770-128469">Sir Joseph Banks</a>, who collected specimens of four species in 1770 when he arrived in Australia on board Captain Cook’s Endeavour. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/botany-and-the-colonisation-of-australia-in-1770-128469">Botany and the colonisation of Australia in 1770</a>
</strong>
</em>
</p>
<hr>
<p>One of the four species he collected was <em>B. integrifolia</em>, the coastal banksia. This can be a small to medium tree about 5m to 15m tall. In the right conditions, it can be quite impressive and grow up to 35m. </p>
<p>It’s found naturally in coastal regions, growing on sand dunes or around coastal marshes from Queensland to Victoria. These can be quite tough environments and, while <em>B. integrifolia</em> tends to grow in slightly protected sites, it still copes well with sandy soils, poor soil nutrition, salt and wind.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341066/original/file-20200611-114066-11d96vm.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">In the right conditions, coastal banksia can grow to 35m tall.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>From ancient origins</h2>
<p>Coastal banksia – like all banksias – belong to <a href="https://trove.nla.gov.au/work/14599266?q&versionId=45817129">the protea family</a> (Proteaceae). But given the spectacular flowering proteas are of African origin, how did our Australian genera get here?</p>
<p>The members of the Proteaceae belong to an ancient group of flowering plants that evolved almost 100 million years ago on the southern supercontinent Gondwana. When Gondwana fragmented more than 80 million years ago, the proteas remained on the African plate, while the Australian genera remained here.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-firewood-banksia-is-bursting-with-beauty-112696">The firewood banksia is bursting with beauty</a>
</strong>
</em>
</p>
<hr>
<p>The spikes of woody fruits on the Australian banksia, sometimes called cones, are made up of several hundred flowers. The flower spikes are beautiful structures, soft and brush-like. But with <em>B. integrifolia</em>, they are pale green, similar to the foliage, and can be hard to see within the canopy at a distance.</p>
<p>Up close, these fruit spikes can look quite spooky, almost sinister, especially when wasps have caused <a href="https://www.sgaonline.org.au/gall-of-australian-native-trees/">extensive gall formation</a>. Galls are swellings that develop on plant tissues as a result of fungal and insect damage, a bit like a benign tumour. </p>
<p>Maybe this is what led May Gibbs to cast them as <a href="https://www.maygibbs.org/characters/big-bad-banksia-men/">the baddies</a> in her Gumnut Baby stories. While the galls may look unsightly, they rarely do serious harm to banksias.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=723&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=723&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=723&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=908&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=908&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341056/original/file-20200611-114066-i21m2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=908&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Banksias were depicted as the Big Bad Banksia Men in May Gibbs’s Gumnut stories.</span>
<span class="attribution"><a class="source" href="https://maygibbs.org/characters/big-bad-banksia-men/">May Gibbs/The Northcott Society and Cerebral Palsy Alliance</a></span>
</figcaption>
</figure>
<h2>Indigenous use</h2>
<p>Given the fruit spikes of coastal banksia look like brushes, it’s not surprising Indigenous people once used them as <a href="https://www.monash.edu/__data/assets/pdf_file/0004/542119/Guide-to-the-Aboriginal-Garden-Clayton-Campus.pdf">paint brushes</a>. </p>
<p>The flowers <a href="https://www.publish.csiro.au/BT/BT9850705" title="Flowering Biology and Phenology of Banksia integrifolia and B. spinulosa (Proteaceae) in New England National Park, NSW">are very rich in nectar</a>, which attracts insects and birds. If you run your hand along the flower spike you, like generations of Aboriginal people before you, can enjoy the sweet taste if you lick the nectar off your hand. You can also soak the flowers in water and collect a sweet syrup. </p>
<p>In the garden, <em>B. integrifolia</em> is wonderfully attractive to native insects, birds and ringtail possums. It’s easy to establish and, until it grows more than a few metres high, can be successfully moved and transplanted.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341064/original/file-20200611-114124-1uflyxn.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">Coastal banksia doesn’t need fire to release its seed.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Unlike many other banksia species, coastal banksias don’t need fire to release their seed. For many Australian species, the woody fruits remain solid and sealed, and it’s only when fire comes through that they burn, dry, crack open and release their seed.</p>
<p>This can happen with <em>B. integrifolia</em> too, but in a garden setting the fruits will mature, dry and crack open and release the seeds, which germinate readily. This makes propagating coastal banksia easy work.</p>
<h2>In touch with its roots</h2>
<p>Perhaps one of the more important, but less obvious, attributes of <em>B. integrifolia</em> are its roots. These are a special type of root possessed by members of the protea family.</p>
<p>The roots form a dense, branched cluster, a bit like the head of a toothbrush, that can be 2-5cm across. They greatly increase the absorbing surface area of the roots, as each root possesses thousands of very fine root hairs.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-black-wattle-is-a-boon-for-australians-and-a-pest-everywhere-else-100529">The black wattle is a boon for Australians (and a pest everywhere else)</a>
</strong>
</em>
</p>
<hr>
<p>Proteoid roots can be very handy in sandy and other poor soils, where water drains quickly and nutrients are scarce.</p>
<p>These roots, also described as cluster roots, are often visible in a garden bed just at the interface of the soil with the humus or mulch layer above it. They’re very light brown, almost white, in colour.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341390/original/file-20200612-38702-59lnis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rainbow lorikeets love hanging around in banksias.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/salihan/5567118988/">Flickr/Salihan</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p><em>B. integrifolia</em>, like other banksias, also has the ability to take in nitrogen and enrich the soil, which can be very handy in soils low in nitrogen. It’s like a natural living and decorative fertiliser.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/after-the-bushfires-we-helped-choose-the-animals-and-plants-in-most-need-heres-how-we-did-it-138736">After the bushfires, we helped choose the animals and plants in most need. Here's how we did it</a>
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</em>
</p>
<hr>
<p>Proteoid roots are unfortunately very well suited to the presence of <em>Phytophthora cinnamomii</em> (the cinnamon fungus). It causes dieback in many native plant species, but can be particularly virulent for banksias.</p>
<p>But <em>B. Integrifolia</em> is one of the more <a href="https://www.google.com/books/edition/Native_Australian_Plants/1G4lAQAAMAAJ?hl=en" title="Native Australian Plants">resistant species</a> to the fungus. Promising experiments have been done on grafting susceptible species onto the roots of <em>B. integrifolia</em> to improve their rates of survival.</p>
<p>This could be important, as banksias have a role in bushfire regeneration in many parts of Australia, so the occurrence of the fungus can compromise fire recovery.</p><img src="https://counter.theconversation.com/content/138434/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Moore 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 plant takes its name from the colonial botanist Joseph Banks, but the coastal banksia’s history goes way back to ancient times.
Gregory Moore, Doctor of Botany, The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/137380
2020-04-29T20:04:00Z
2020-04-29T20:04:00Z
Say hello to the ‘crazy beast’ mammal who lived among the dinosaurs
<figure><img src="https://images.theconversation.com/files/330918/original/file-20200428-76576-1m8yy1m.jpg?ixlib=rb-1.1.0&rect=0%2C37%2C2500%2C1362&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Scott Hartman (skeletaldrawing@gmail.com)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A species of mammal that lived in what is now Madagascar when dinosaurs roamed the island has finally been <a href="https://www.nature.com/articles/s41586-020-2234-8" title="Skeleton of a Cretaceous mammal from Madagascar reflects long-term insularity">described today in Nature</a>. </p>
<p>The work is based on a complete skeleton of the animal found more than two decades ago.</p>
<p>The cat-sized animal, known as <em>Adalatherium hui</em> or “crazy beast”, has features not found in today’s mammals, so it could be one of evolution’s abandoned experiments in developing new life.</p>
<h2>The origin of mammals</h2>
<p>Almost all the mammals today fall into two groups: the placentals (which includes dogs, mice, whales, cows and us) and marsupials (kangaroos, the koala and the Tasmanian devil). While very distinctive today, both these groups were mostly small and mouse-like in the time of the dinosaurs. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-we-know-if-a-dinosaur-skeleton-is-from-a-child-dinosaur-or-an-adult-dinosaur-125562">Curious Kids: how do we know if a dinosaur skeleton is from a child dinosaur or an adult dinosaur?</a>
</strong>
</em>
</p>
<hr>
<p>During this time, several other types of mammals roamed the Earth. Some were the ancestors of modern mammals, but many others are long extinct. We see glimpses into these little known and extinct mammal groups but they are a mystery to us.</p>
<p>Since the 1980s strange fossil teeth have been found in places such as <a href="https://link.springer.com/article/10.1007/s00114-012-0919-z" title="Persistence of a Mesozoic, non-therian mammalian lineage (Gondwanatheria) in the mid-Paleogene of Patagonia">South America</a>, <a href="https://www.tandfonline.com/doi/abs/10.1671/0272-4634%282007%2927%5B521%3ALCSGFI%5D2.0.CO%3B2" title="Late Cretaceous sudamericid gondwanatherians from India with paleobiogeographic considerations of Gondwanan mammals">India</a> and <a href="https://www.researchgate.net/publication/242879814_Cosmopolitanism_among_Gondwanan_Late_Cretaceous_mammals" title="Cosmopolitanism among Gondwanan Late Cretaceous mammals">Madagascar</a>. These modern landmasses were once joined as part of the southern supercontinent known as <a href="https://www.britannica.com/place/Gondwana-supercontinent">Gondwana</a>. The strange fossil mammals found there are named the Gondwanatheria.</p>
<p>When all that is known of an animal is its teeth, it is a challenge to distinguish what exactly it is and how it relates to the fossil remains of better understood groups of early mammals.</p>
<h2>We needed a skeleton</h2>
<p>The breakthrough came when a team of palaeontologists (led by Dave Krause) discovered the first intact skeleton during excavations in Madagascar in 1999.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331233/original/file-20200429-110770-1h5hm87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A plaster jacket containing the skeleton of <em>Adalatherium hui</em> is carried from the excavation site. (David Krause, front left).</span>
<span class="attribution"><span class="source">Photo courtesy of National Geographic Society/Maria Stenzel.</span></span>
</figcaption>
</figure>
<p>This remarkable find, dated to near the end of the <a href="https://www.britannica.com/science/Cretaceous-Period">Cretaceous period</a> (66 million years ago), showed gondwanatherians were different from all other mammals known.</p>
<p>There were so many mysteries surrounding how this animal looked that it remained a challenge to relate this species back to other mammals. As a result, the process of scientific description was long and complicated.</p>
<h2>Introducing the ‘crazy beast’</h2>
<p>We gave the full skeleton the name <em>Adalatherium hui</em>. It’s a combination of a Malagasy word “Adàla” meaning “crazy” and Greek word “therium” for “beast”, in reference to the many strange features found in this unusual mammal.</p>
<p>The skeleton was encased in a block of sandstone, which was delicately sculpted away to reveal the bones in almost life position.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=407&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=407&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330919/original/file-20200428-76598-1hd2eh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=407&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Skeleton of <em>Adalatherium hui</em> in sandstone.</span>
<span class="attribution"><span class="source">Marylou Stewart</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Because it was so fragile, we relied on X-ray <a href="https://www.microphotonics.com/what-is-micro-ct-an-introduction/">microCT</a> scanning through the rock to digitally map the bones and teeth. Some of the fossil parts were shattered, the back teeth and the braincase in particular.</p>
<p>Over hundreds of hours, the minute fragments of teeth were painstakingly put back together in a 3D jigsaw puzzle in the computer.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/s5wNuqkaIlQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption"><em>Adalatherium</em> tooth being reconstructed.</span></figcaption>
</figure>
<p>Each component could then be 3D-printed at real size, or enlarged to see the features better.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331228/original/file-20200429-110757-ml4n1x.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">Alistair Evans with 3D-printed <em>Adalatherium</em> teeth at four times real size.</span>
<span class="attribution"><span class="source">Gudrun Evans</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A most bizarre mammal</h2>
<p>There is much about this animal that was so unusual. Features of the skull (the largest number of small holes for nerves and blood vessels in any mammal) and ear bones (small ridges inside the cochlea) have never been found in other mammals. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/cY8jVAsjdrM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption"><em>Adalatherium</em> skeleton and 3D reconstruction.</span></figcaption>
</figure>
<p>Among the most bizarre features in <em>Adalatherium</em> are its teeth. Not only did this species have mouse-like ever-growing front teeth, but the rear teeth are completely unlike those of any other mammal that has ever been described. </p>
<p>The ridges and bumps on teeth are generally very consistent within each group of mammals, so they can act like a fingerprint to tell us who they are. <em>Adalatherium</em> has a new fingerprint, with a diamond-shaped ridge running around the outside of each tooth that interlocks with its opposing tooth in the other jaw.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331231/original/file-20200429-110775-1nezuc4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mounted cast skeleton of <em>Adalatherium hui</em>.</span>
<span class="attribution"><span class="source">Courtesy of Triebold Paleontology.</span></span>
</figcaption>
</figure>
<p>From examining its unusually bowed leg bones, strong back muscles and big claws on the back feet, we suggest <em>Adalatherium</em> was a robust animal, perhaps capable of digging for food or shelter. Its unusual teeth may indicate a plant diet.</p>
<p>The dramatic differences between <em>Adalatherium</em> and all other mammals known, past and present, shows there is more than one way to be a mammal.</p>
<p>The Gondwanatherians therefore represent an experiment in evolution, one of a number of early mammal groups where different body shapes and ways of life were still being tinkered with, before most died out, leaving the familiar mammals of today.</p>
<h2>Island life for dinosaur-age mammals</h2>
<p>One reason this group became so different likely relates back to where it was living: on an island.</p>
<p><em>Adalatherium</em> lived in what is now Madagascar, which at that time had already been set adrift, separated from what became mainland Africa and the other major landmasses for tens of millions of years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-smart-were-our-ancestors-turns-out-the-answer-isnt-in-brain-size-but-blood-flow-130387">How smart were our ancestors? Turns out the answer isn't in brain size, but blood flow</a>
</strong>
</em>
</p>
<hr>
<p>Strange things can happen on islands. Very large animals evolve to become smaller, perhaps because there is not enough food on the island to feed a population of giants.</p>
<p>Conversely, very small animals sometimes evolve to become larger, especially if there are no large predators on the island with them. Such was the case with the <a href="https://www.nationalgeographic.com/news/2015/2/150217-lemur-cave-madagascar-graveyard/">gorilla-sized lemurs</a> that lived on Madagascar only a few thousand years ago, before humans arrived.</p>
<p>This is known as the <a href="https://www.pbs.org/wgbh/nova/article/gigantism-and-dwarfism-islands/">island effect</a> and may explain why <em>Adalatherium</em> is one of the largest mammals of its era. It was around the size of a domestic cat at about 3.1kg, possibly due to its freedom from competitors on its island home.</p><img src="https://counter.theconversation.com/content/137380/count.gif" alt="The Conversation" width="1" height="1" />
<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>David Krause receives funding from the U.S. National Science Foundation. David Krause is also the Founder and CEO of the Madagascar Ankizy Fund (<a href="http://www.ankizy.org">www.ankizy.org</a>), a not-for-profit organization whose mission it is to provide education and healthcare to children living in remote areas of Madagascar.
</span></em></p><p class="fine-print"><em><span>Simone Hoffmann receives funding from The National Science Foundation. </span></em></p>
This ancient cat-sized animal lived millions of years ago and had features not found in any of today’s mammals.
Alistair Evans, Associate Professor, Monash University
David Krause, Emeritus Distinguished Service Professor, Stony Brook University (The State University of New York)
Simone Hoffmann, Assistant professor, New York Institute of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/130215
2020-01-30T06:47:23Z
2020-01-30T06:47:23Z
Fossil footprints show how life endured amid volcanic eruptions 183 million years ago
<figure><img src="https://images.theconversation.com/files/310848/original/file-20200120-69559-9qh8iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reconstruction of the ancient environment at the Highlands trace fossil site about 183 million years ago. </span> <span class="attribution"><span class="source">Artwork by Akhil Rampersadh. Heterodontosaurid silhouette is courtesy of Viktor Radermacher.</span></span></figcaption></figure><p>Fossil footprints provide a special source of scientific evidence. They reveal how animals walked and how large they were. In some cases where there are no body fossils like bones, trace fossils such as footprints or trackways may be the only evidence that animals were present in an ancient environment. </p>
<p>In <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">our new publication</a>, using techniques that have been honed by ichnologists – those who study trace fossils – we examined the trackways of land-dwelling vertebrates in what is today a farm in the centre of South Africa. These fossil trackways are preserved in sandstones within a thick pile of basaltic lava flows. They offer rare insights about ancient life in a stressful, hostile environment some 183 million years ago in the Early Jurassic.</p>
<p>This <a href="http://stratigraphy.org/index.php/ics-chart-timescale">geological epoch</a> is probably best known in the public imagination as the dawn of the age of the dinosaurs. Towards the end of the Early Jurassic, a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">major geological event devastated life</a>, especially in the oceans.</p>
<p>This mass extinction event was caused by, among other things, the degassing of the extensive lava flows that poured out during volcanic eruptions in the southern part of the <a href="https://www.livescience.com/37285-gondwana.html">supercontinent Gondwana</a>. These volcanic eruptions changed the chemistry of the ancient atmosphere and oceans at the time.</p>
<p>But in between the voluminous volcanic eruptions, the environment and life in it occasionally recovered. It was during these intermittent periods that the movement of animals across the land surface could be captured as the fossil trackways we study today. </p>
<p>These ancient footprints are important because they tell us about the type of Early Jurassic animal life, and because the tracks bring together different earth science disciplines that can help us visualise what the ancient world looked like.</p>
<h2>Reconstructing a landscape</h2>
<p>There was more to our research than just reconstructing what individual animal species were and how they moved. We also had to reconstruct the ancient environment in which these animals lived. For this we had to incorporate existing findings from different academic disciplines.</p>
<p>Geologists, including stratigraphers, volcanologists, geochronologists and sedimentologists, as well as palaeontologists, palaeobotanists and others, were all involved in studying these rocks before us. They gathered evidence about the properties of the sedimentary rocks that host the tracks; the plant fossils associated with these rocks; and the age, composition and structure of the ancient lava flows that entombed the track-bearing sediment surface.</p>
<p>Drawing from this existing research and our own work, our collective observations show that when vast sheets of lava flowed across the landscape, the environment turned into a land of fire. But during the quieter periods life returned to normal: streams ran, the sun shone, plants grew and the animals, among them dinosaurs, grazed and hunted. </p>
<p>What emerges is a picture not just of devastation wrought by volcanic eruptions, but one of a functioning ecosystem that endured despite environmental threats.</p>
<h2>A new ichnospecies</h2>
<p>Our research also unearthed a new species of dinosaur footprint. The best-preserved trackways at the Highlands farm site were made by dinosaurs – both meat-eating ones which walked on two legs, as well as plant-eating ones which walked on four legs. Less well-preserved trackways are more difficult to interpret. But those we studied appear to have been potentially made by <a href="https://nasmus.co.za/palaeontology/">synapsids</a>, a group of reptiles that are considered to be the ancestors of mammals. The synapsids have <a href="https://theconversation.com/why-south-africas-karoo-is-a-palaeontological-wonderland-43045">a rich skeletal record</a> in South Africa. </p>
<p>To identify the trackmakers, we carefully compared the morphology of the tracks – for example the shape, size and angles between the toe impressions – to other known tracks around the world. Some had characteristics common in footprints made by theropods, a group of carnivorous dinosaurs. But some showed features known only in tracks of ornithischians, a group of herbivorous dinosaurs. </p>
<p>We then closely compared our observations to those previously reported, and were able to come up with a list of diagnostic features that define the new ichnospecies. We named it after a French priest and trace fossil expert, Dr Paul Ellenberger, who is considered <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226847">the father of vertebrate ichnology</a> in southern Africa. </p>
<h2>Significance of the South African fossil heritage</h2>
<p>South Africa is a global epicentre for palaeontology. <a href="https://theconversation.com/five-reasons-why-2018-was-a-big-year-for-palaeontology-106725">Discoveries</a> made in the country have showcased some of the first animals to walk on land, some of the first mammals, the first turtles, early dinosaurs, and hominids. </p>
<p>But the country’s famous fossils only truly help us understand the history of life on Earth if their geological and palaeoenvironmental contexts are also described. Placed in their ancient environmental setting, these Early Jurassic trackways show that some animal life was resilient even as the environment changed and was hit by catastrophic events.</p><img src="https://counter.theconversation.com/content/130215/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emese M Bordy receives funding from the Centre of Excellence in Palaeosciences (COE-PAL National Research Foundation-DST), the National Research Foundation of South Africa and the University of Cape Town.</span></em></p>
These trackways offer rare insights about ancient life in a stressful, hostile environment during the Early Jurassic.
Emese M Bordy, Associate Professor in Geological Sciences, University of Cape Town
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/105148
2018-11-20T13:19:59Z
2018-11-20T13:19:59Z
Rocks hold clues about how falling sea levels caused havoc 400 million years ago
<figure><img src="https://images.theconversation.com/files/245155/original/file-20181112-83596-og9ffx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Klipbokberg, Grootrivierhoogte, in the Cederberg. These mountains contain clues about ancient landscapes.</span> <span class="attribution"><span class="source">Cameron Penn-Clarke</span></span></figcaption></figure><p>The Earth was a very different place 400 million years ago, during what’s known as the <a href="https://www.livescience.com/43596-devonian-period.html">Devonian Period</a>. Africa, Antarctica, South America, India, Australia, Madagascar, parts of Asia and even Florida were part of the large super-continent, <a href="https://www.livescience.com/37285-gondwana.html">Gondwana</a>. It occupied a substantial area south of the equator. </p>
<p>Large parts of southernmost Gondwana (including what we know today as South Africa, Antarctica, Falkland Islands and parts of South America) were situated over the South Pole throughout this period. </p>
<p>By observing the types of rocks, minerals and sediments that form in different climates today, we are able to use this information to get a picture about what the climate was like during the Devonian Period. Similarly, we can use Devonian fossils to work out climates based on the environments and climates these organisms are found in today. </p>
<p>They’re also vital for inferring sea-level changes through time – and how both climate and sea-level affected marine creatures of the Devonian.</p>
<p>What is interesting is that there is no evidence of extensive ice sheets at the South Pole during the Devonian Period, as we have today covering Antarctica. Of course, there are polar ice caps in the region today. This suggests that climatic belts were distributed differently then, and have shifted through time.</p>
<p>During the Devonian, certain groups of animals congregated around the equator. Others were found in more temperate regions. A group known as the Malvinokaffric Fauna was located around the South Pole. The Malvinokaffric Fauna were a group of marine invertebrates only found in what we know as South Africa, Antarctica, the Falkland Islands and parts of South America. </p>
<p>We don’t know much about their ecology, where they came from or why they disappeared, nor about the environments they lived in around what was then the South Pole and is South Africa today. That’s where <a href="https://www.researchgate.net/profile/Cameron_Penn-Clarke2">my research</a> comes in. </p>
<p>My findings, drawn from the study of certain rocks and their sediment, as well as remnants of biological activity called trace fossils, suggest the Malvinokaffric Fauna in the Devonian South Pole were wiped out because of falling sea levels. </p>
<p>We don’t yet know what caused the drop in sea levels. But my research offers evidence of a previously unrecorded large extinction event during the Devonian, a period which experienced several such events.</p>
<h2>Wiped out</h2>
<p>South Africa has perhaps one of the best preserved and most complete records of Gondwana during the Devonian Period at polar latitudes. This record is preserved in the rocks of the uppermost Table Mountain, Bokkeveld and lower Witteberg Groups within the Cape Mountains along the country’s southern margin. </p>
<p>I study and interpret both the palaeontology and sedimentology of these rocks. I also look for any trace fossils such as trackways and burrows in the rocks. Trace fossils indicate a biological organism’s activity, which is directly related to its ecology and environment. </p>
<p>By examining sedimentary rocks, fossils and trace fossils, I’ve been able to form a picture of the lives and times of the Malvinokaffric Fauna in South Africa. From there, I can infer whether environmental changes were sudden and rapid or long-lived and gradual and how they affected the Malvinokaffric Fauna.</p>
<p>I’ve found that because this group of animals lived in certain environments, they were very sensitive to periods of excessive falling in sea-level, particularly sea level drops greater than 10 m. </p>
<p>Coincidently, the disappearance of the Malvinokaffric Fauna in South Africa is gradual and occurs with a gradual trend of falling sea-level that is observed in the rocks of the upper Bokkeveld Group. Evidence from the meagre fossil and trace fossil record after this event suggest that the disappearance of the Malvinokaffric Fauna resulted in a total collapse in marine ecosystems around the South Pole. </p>
<p>Even though different immigrant organisms from elsewhere moved in during a subsequent rise in sea-level, they never truly were able to reach the diversity of the Malvinokaffric Fauna, nor to form stable ecosystems. Life around the South Pole seems to have only truly recovered in South Africa in the Late Devonian, between 370 and 360 million years ago.</p>
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Read more:
<a href="https://theconversation.com/fossil-find-offers-first-evidence-of-four-legged-aquatic-ancestors-in-africa-97747">Fossil find offers first evidence of four-legged aquatic ancestors in Africa</a>
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<p>What I have found suggests that many shallow marine environments – beaches, shorefaces, deltas, barrier islands, lagoons and estuaries – dotted South Africa’s shoreline throughout the Devonian. </p>
<p>Initially, sea levels were low. Then about 400 million years ago they rose, only to gradually fall some 10-15 million years later. It was during this period of rising sea-level that the Malvinokaffric Fauna made their appearance in South Africa and are found in the rocks of the upper Table Mountain Group and the lower Bokkeveld Group. </p>
<p>My research indicates that these animals lived and thrived in deeper water conditions, preferably within the deepest portions of the shoreface and offshore environments where they formed specific ecosystems.</p>
<p>Now that we know that falling sea-levels probably caused the fauna to vanish. The hunt is now on to find what caused sea-level to drop.</p>
<h2>Tracking the extinction</h2>
<p>There are several possible answers, which I’m exploring in new, ongoing research. </p>
<p>For instance, local tectonic events may have caused the sea to change its configuration and sea-level to fall. Or, perhaps a global event like climatic shifts caused sea-level fall.</p>
<p>The Devonian, after all, is a time marred by extinction events that seem to be on a global scale, ultimately linked to changes in climate. </p>
<p>Right now, I don’t have the answers. But I’m exploring ways to precisely date these rocks, and see if they correlate with known local or global events and tease out the solutions from there. Hopefully soon we’ll know more about the event that wiped out the Malvinokaffric Fauna.</p><img src="https://counter.theconversation.com/content/105148/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Penn-Clarke receives funding from the South African Department of Science and Technology-National Research Foundation Centre of Excellence in Palaeosciences (DST-NRF CoE in Palaeosciences), the African Origins Platform (DST-NRF AoP) as well as the Palaeontological Scientific Trust (PAST).
He is a scientist at the Council for Geoscience, Bellville Office and is an honorary research associate of the Evolutionary Studies Institute, University of the Witwatersrand. He is also a stratigrapher for the South African Committee on Stratigraphy and is the South African associate member for the International Subcommission on Devonian Stratigraphy (International Commission on Stratigraphy).</span></em></p>
A record of sea-level change from 400 million years ago in South Africa, reveals how ecosystems and environments collapsed at the South Pole.
Cameron Penn-Clarke, Scientist and Honorary Research Associate, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/100824
2018-10-19T01:50:23Z
2018-10-19T01:50:23Z
When Thailand and Australia were closer neighbours, tectonically speaking
<figure><img src="https://images.theconversation.com/files/241362/original/file-20181019-67161-d7ghtq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The beaches of Koh Phangan are set within rocky crags made of granites, the type of rocks studied to piece Thailand to Australia.</span> <span class="attribution"><span class="source">Romana Dew</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Thousands of Australians travel to Thailand each year to lie on a beach at Phuket, meditate at a Buddhist temple in Ayutthaya, spot wild elephants at Khao Yai National Park, or go on some other adventure. </p>
<p>But how many realise that beneath their feet, the framework of the country once formed part of the same continent as Australia? </p>
<p>Our new research, <a href="https://doi.org/10.1016/j.lithos.2018.09.019">published in Lithos</a>, uncovered the deep links between Australia and Thailand, rebuilding the geography of this part of the ancient supersized continent <a href="https://www.britannica.com/place/Gondwana-supercontinent">Gondwana</a>.</p>
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Read more:
<a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">A map that fills a 500-million year gap in Earth's history</a>
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<p>This was a time before the dinosaurs, when the first forests turned the land green and <a href="https://news.nationalgeographic.com/news/2011/08/110808-ancient-insects-bugs-giants-oxygen-animals-science/">giant dragonflies</a> tracked airways through the vegetation.</p>
<p>Our work suggests that some fictional time-travelling Phuket beach-lover could have walked to the Pilbara in Western Australia. A pre-Jurassic culture vulture in Ayutthaya could have trekked over an ancient Indonesian-like volcanic island chain, and some Khao Yai elephant-ancestor could have rampaged through the site of the Perth CBD.</p>
<h2>On the move</h2>
<p>Tracking these bits of continents and their dance across the globe is part of a large effort to map our planet through its history. Last year we published a <a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">map of half a billion years of Earth history</a>. </p>
<p>This was one of the first forays into mapping Earth in deep time. But putting the details on these maps is far from straightforward. </p>
<p>To do this, scientists first try to find geological hints in the rocks of two regions to suggest they are related to each other and have similar histories. </p>
<p>The problem with much of Southeast Asia is that the rocks on the surface are too young – they left Gondwana between 400 million and 300 million years ago, and the rocks we need to see are now buried.</p>
<p>Our research gets around this by using some of these young rocks – granites that formed the roots of old volcanoes – as upside-down probes to fingerprint the deeper Earth.</p>
<p>The idea is that the granite magma mixed a little with the older rocks below as it worked its way up in the crust, forming a unique molten rock soup with subtle chemical differences that can help map the geological basement.</p>
<p>Our study in Thailand used granites, between 500 million and 80 million years old, to discover these characteristics of the older underlying basement rocks. These granites contained chemical markers from the magma that can date when it formed and separated from the mantle. In some cases, these date back nearly 3 billion years. </p>
<h2>The three blocks of Thailand</h2>
<p>Thailand may be one country now, but it is made up of three distinct geological regions: Sibumasu, Sukhothai, and Indochina.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1032&fit=crop&dpr=1 600w, https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1032&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1032&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1296&fit=crop&dpr=1 754w, https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1296&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/238006/original/file-20180926-149952-1pheh8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1296&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 Thailand including the three main blocks (Sibumasu, Sukhothai and Indochina), major cities and landmarks.</span>
<span class="attribution"><span class="source">Romana Dew</span></span>
</figcaption>
</figure>
<p>These three blocks all originated in different parts of Gondwana and collided about 200 million years ago. That is a long time ago, but geologically not so old when you consider that the planet is 4,650 million years old. </p>
<p>Sibumasu makes up most of the Thai peninsula and follows north into northwestern Thailand past <a href="https://www.news.com.au/travel/world-travel/asia/thai-cave-could-be-turned-into-a-tourist-attraction-and-hollywood-film/news-story/4b351c78d07a4ad66a4185efe8b60a24">Tham Luang cave</a> – where the young soccer team and coach were rescued earlier this year – and into Myanmar.</p>
<p>Sukhothai is a volcanic arc system like modern Indonesia or Japan. It cuts through the middle of Thailand past the historic city of Sukhothai, extending southeast to the ruby and sapphire market town of Chanthaburi.</p>
<p>Indochina includes everything in Thailand east of the Sukhothai block, and extends into Cambodia and Vietnam.</p>
<h2>Three blocks, three different fingerprints</h2>
<p>Although these three blocks form one country today, their telltale chemical fingerprints show a varied history. Sibumasu has very ancient isotopic markers, similar to parts of northwestern Australia. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whats-australia-made-of-geologically-it-depends-on-the-state-youre-in-83575">What's Australia made of? Geologically, it depends on the state you're in</a>
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</p>
<hr>
<p>But the granites from Indochina tell a different, shorter story. The chemical fingerprints from this block show that it formed from melting of the deep Earth much more recently than Sibumasu.</p>
<p>This eastern region formed only between 1.28 billion and 500 million years ago – still very old, granted, but not nearly as old as the Thai Peninsula and Sibumasu. Similar compositions of rocks occurred smeared along the west coast of Australia, and especially in the Margaret River wine region of Western Australia.</p>
<p>The Sukhothai block is chemically somewhere between Sibumasu and Indochina, with separation from the deep earth mantle modelled between 1.74 billion and 850 million years ago. </p>
<p>These intermediate values from the Sukhothai granites are probably a result of mixing of the more youthful Indochina with ancient recycled Sibumasu when the blocks collided and one was pushed over the other. </p>
<h2>Thai-Australian reunion?</h2>
<p><a href="https://www.sciencealert.com/australia-s-about-to-move-1-5-metres-to-the-north">Australia is currently moving north</a> by up to seven centimetres per year. As we creep towards Asia, like it or lump it, Australia’s future really is with Asia.</p>
<p>So Australians, just hang on, enjoy the ride, in a few tens of million years the southern Thai beaches will be a short drive away. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239643/original/file-20181008-72113-cunq4b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rocks of Central Thailand folded by the collisions that grew Asia.</span>
<span class="attribution"><span class="source">Alan Collins</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/100824/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alan Collins receives funding from Australian state and federal government sources, including the Australian Research Council, as well as funding from petroleum and minerals companies and charities. </span></em></p><p class="fine-print"><em><span>Romana Dew receives funding through The University of Adelaide Research Training Program Stipend and some of the fieldwork was conducted on an Endeavour Australia Cheung Kong Fellowship.</span></em></p>
Australia’s slowly heading north to one day become part of Asia, but a study of the rocks tell us that’s not the first time there’s been a connection.
Alan Collins, Professor of Geology, University of Adelaide
Romana Dew, Geology PhD Candidate, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/91014
2018-03-08T14:16:47Z
2018-03-08T14:16:47Z
Plant fossils have a lot to teach us about Earth’s history
<figure><img src="https://images.theconversation.com/files/204207/original/file-20180131-131733-fxwavj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reconstruction of a Permian swamp.</span> <span class="attribution"><span class="source">Rose Prevec</span></span></figcaption></figure><p>There’s a particular feeling of excitement that comes from receiving a gift. It’s a feeling of the unknown, of anticipation – and then you unwrap the package and find something spectacular. </p>
<p>As palaeontologists, rocks are our idea of a great gift. That’s because when you crack them open, you might well find a fossil. And we aren’t talking about dinosaurs: our area of specialisation is palaeobotany. This involves hunting for plant fossils which can tell us a great deal about the landscapes of past ages.</p>
<p>South Africa is home to a range of lesser known and neglected plant fossils, called the <a href="http://www.ucmp.berkeley.edu/seedplants/pteridosperms/glossopterids.html">glossopterids</a>. These trees once grew in vast swamps along with ancient plant groups such as ferns, horsetail ferns and clubmosses. We know from a few scattered reports that this amazingly rich fossil resource extends across much of Africa, particularly in Namibia, Zimbabwe, Mozambique and further north into Zambia, Tanzania, Kenya and even Madagascar. </p>
<p>Some may wonder why fossils matter. Plants never get as much attention as South Africa’s famous <a href="http://www.maropeng.co.za/videos/entry/south_africas_fossil_record_dates_back_more_than_300-million_years">rich and diverse fossil heritage</a> that range from some of the earliest evidence of life through to its famous hominid collections. <em>Glossopteris</em>, for instance, has not been well studied in South Africa. It’s still poorly understood. </p>
<p>There has been work done in different parts of the world. However, it is not detailed and each region uses its own system to try and understand these fossil plants. South Africa is lagging behind: there are two employed palaeobotanists in the country, while entire research teams exist in other parts of the world.</p>
<p>Yet plants can reveal a great deal about past environments and climates. If we have any hope of understanding South Africa’s ancient past, scientists need to be able to reconstruct entire ecosystems, starting at the bottom of the food chain. <em>Glossopteris</em> dotted ancient landscapes before dinosaurs ever walked the earth, and before a single flower had bloomed. As such, it should be closely studied.</p>
<h2>What we know</h2>
<p>About 300 million years ago Earth entered what’s known as the Permian period. During this time, and until about 252 million years ago, the <em>Glossopteris</em> plant became a common sight throughout <a href="https://www.sciencedirect.com/science/article/pii/S0034666709000839">Gondwana</a>. This was a super continent that included regions known today as Africa, Antarctica, Australia, India and South America. </p>
<p>The presence of <em>Glossopteris</em> was used as supporting evidence for the revolutionary theory of “<a href="https://www.researchgate.net/profile/Stephen_Mcloughlin/publication/216695699_The_breakup_history_of_Gondwana_and_its_impact_on_pre-Cenozoic_floristic_provincialism/links/0d14c3c38253652003ca038a.pdf">continental drift</a>” during the mid 20th century. They literally reveal how the world we recognise today took shape.</p>
<p><em>Glossopteris</em> was easy to recognise because of its distinctive leaves; the name means “tongue-fern”
in Greek, because of its shape. Fossil evidence suggests that the plants probably grew in diverse habitats and came in different forms. These ranged from short shrubs to trees as tall as a five-story building. </p>
<p>Scientists suggest that at least some of these plants were deciduous because their leaves are often found preserved in thick mats thought to be the result of seasonal shedding. At that point, they became not only important for understanding our history: they started contributing to fuels and materials that are still used today.</p>
<h2>Power plants</h2>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BUSNEQLgsAm/?taken-by=palaeo_botanists","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Dead material from these plants accumulated in swamp environments, was buried, and over time formed South Africa’s <a href="https://www.researchgate.net/publication/313611059_The_life_of_coal_ancient_forests_that_power_our_nation">vast coal reserves</a>.</p>
<p>Under normal conditions, when plants die or shed their leaves these fall to the ground and decompose. Under special environmental conditions – such as those that occurred in the vast Permian swamps of Gondwana (which were a bit like today’s mangrove swamps) – the process differs. Once <em>Glossopteris</em> shed their leaves, the plant material accumulated in acidic water with high levels of tannins and low oxygen concentrations. </p>
<p>This retarded the activity of the bacteria, fungi and other organisms that would otherwise lead to decomposition. Over time layers of mud, silt and sand washed into the swamp and buried the waterlogged peat layers. Millions of years passed. During this period the mud, silt, sand and the encased plant material experienced great pressure and high temperatures. It was compressed and changed into rock, and underwent various chemical changes. </p>
<p>The result? Coal seams. This is why coal is referred to as a fossil fuel. It is also a reminder that coal is finite. </p>
<p>Apart from being the major source of fuel in the production of South Africa’s electricity, <em>Glossopteris</em> influences our lives in many ways. The carbon atoms harvested from the air as carbon dioxide by these trees during the process of photosynthesis, hundreds of millions of years ago, can also be found in petrol, waxes, plastics, and a host of other products used in everyday life.</p>
<h2>New finds</h2>
<p>South Africa has a huge potential for new fossil discoveries, with vast territories still waiting to be explored, yet very few researchers are studying fossil plants and insects. </p>
<p>We are part of a small group of researchers based at the <a href="https://www.facebook.com/Department-of-Earth-Sciences-Albany-Museum-Grahamstown-126375658097835/">Albany Museum</a> in Grahamstown in the Eastern Cape province who are determined to change this by shedding more light on <em>Glossopteris</em> and fossil plants in general.</p>
<p>At the moment we’re working on a few small road cuttings near a Northern Cape town called Sutherland. This is revealing a depth of knowledge about Permian ecosystems that has not been seen before in South Africa, and is very rare on a global scale. </p>
<p>New discoveries are not only about bringing a wonderful piece of the country’s heritage to light. This work is also opening up new scientific fields and opportunities for skills development that the country desperately needs.</p><img src="https://counter.theconversation.com/content/91014/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aviwe Matiwane receives funding from the NRF African Origins Platform; and the DST-NRF Centre of Excellence in Palaeosciences.</span></em></p><p class="fine-print"><em><span>Rosemary Prevec receives funding from the DST-NRF Centre of Excellence in Palaeontology; the African Origins Platform of the NRF and the Eastern Cape Department of Sports, Recreation, Arts and Culture. </span></em></p>
Plants, in their fossil forms, can reveal a great deal about past environments and climates.
Aviwe Matiwane, PhD student, Botany, Rhodes University
Rosemary Prevec, Palaeontologist, Rhodes University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/91849
2018-02-21T15:12:47Z
2018-02-21T15:12:47Z
Africa’s rich fossil finds should get the air time they deserve
<figure><img src="https://images.theconversation.com/files/206384/original/file-20180214-174993-1rvsowu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Spinosaurus was just one example of a dinosaur that roamed Africa hundreds of millions of years ago.</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/b/b2/Spinosaurus_swimming_black_background.jpg">By Mike Bowler from Canada (Spinosaurus) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons</a></span></figcaption></figure><p>Palaeontology, like much else in the cultural landscape, has a strong western influence and bias. Students are more likely than not to be given textbooks and external readings from Europe and North America no matter where they are in the world. </p>
<p>I often think about my own experiences as a palaeontology student in France now that I’m lecturing the subject at a South African university. Back in those days, I knew more about North American and British fossils than about those from my own country. The textbooks haven’t changed much since. So, when I started as a lecturer at Wits University in 2017, I wondered if I should just be talking to my students about North America’s fossil record, or Britain’s. </p>
<p>There are, of course, some <a href="http://www.biologicalsciences.uct.ac.za/bio/staff/academic/chinsamyturan">good books</a> written on the subject from an African perspective. But these are nowhere near as ubiquitous as the works of palaeontologists from North America and Europe.</p>
<p>I decided to set the usual textbooks aside and to create my own lecture series based only on African literature about palaeontology and the continent’s fossil heritage. There were two reasons for this. The first is that while Africa is widely acknowledged as the <a href="https://books.google.co.za/books?isbn=0520257219">birthplace of humankind</a>, its incredibly varied fossil record is often overlooked.</p>
<p>And secondly, how can the continent hope to produce world-class scientists in the future if students aren’t learning about <a href="https://theconversation.com/its-time-to-celebrate-africas-forgotten-fossil-hunters-77345">their own heritage</a>. </p>
<p>Many of the planet’s most important life forms originated in Africa: <a href="https://sciencetoday.co.za/2016/11/14/ancient-sa-bacteria-hold-secret-to-early-life/">bacteria-like organisms</a>; many <a href="https://books.google.co.za/books/about/Famous_Dinosaurs_of_Africa.html?id=YR19JwAACAAJ&redir_esc=y">dinosaur species</a> and, of course primates – including humans. Even the rocks on the continent are among the oldest in the world. Some of them date back more than <a href="https://www.livescience.com/57708-ancient-lost-continent-found-under-mauritius.html">three billion years.</a></p>
<p>From single cells to complex organisms, from sea to land, from small to giant, the continent’s many and breathtakingly diverse landscapes and the soils beneath them have witnessed and recorded all the great transitions in the history of life on Earth. It is crucial to give this unique heritage the attention it deserves so that current students and future generations can better understand the evolutionary processes that have brought us to this point.</p>
<h2>Some crucial moments in time</h2>
<p>Life originated in seas, and the African fossil record documents the <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099438">origin of multicellular organisms</a> two billion years ago in what is today Franceville, a city in Gabon. Fossils in Namibia, meanwhile, represent the <a href="https://books.google.co.za/books/about/The_Fossil_Record_of_Namibia.html?id=nRooAQAAIAAJ&redir_esc=y">Ediacarian biotope</a>, the earliest discovered marine ecosystem, dating back 600 million years and made up entirely of strange, pneumatic creatures that floated.</p>
<p>The rise of fish, too, is well represented in Africa’s fossil records. <a href="http://wiredspace.wits.ac.za/handle/10539/11467">Fossils embedded</a> in South African rocks that date back 320 million years offer evidence of lobe-finned fish (the same family as coelacanths). They’re <a href="https://www.wits.ac.za/news/latest-news/general-news/2015/2015-09/ancient-coelacanth-nursery.html">the ancestors</a> of all terrestrial vertebrates – that is, amphibians and reptiles.</p>
<p>You may think that one of these fish evolved into a walking creature whose new legs took it from the water to the land. But the very first transition from sea to land wasn’t actually achieved by a vertebrate. It was a scorpion, as <a href="http://africaninvertebrates.org/ojs/index.php/AI/article/viewFile/284/252">a fossil</a> also found in South Africa has taught us.</p>
<p>Some fossils found outside modern-day Africa also hold lessons about the continent. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S1464343X05001135">Mesosaurus</a> was a small crocodile-like animal that lived 300 million years ago. <em>Mesosaurus</em> fossils have been found in both Africa – Zimbabwe, Namibia and South Africa – and in Brazil in South America. Its fossil presence in those two very different places made <em>Mesosaurus</em> very important, since this proved that what are today two separate continents were once part of a giant landmass (along with Antarctica, Madagascar and Australia). It was a “supercontinent” called <a href="https://www.sciencedirect.com/science/article/pii/S1464343X05001135">Gondwana</a>.</p>
<p>It was on Gondwana that the earliest dinosaurs were born. And they thrived across what is today Africa. For instance, fossils show that the tallest animal which ever lived – the <a href="https://www.sciencedirect.com/science/article/pii/S1464343X05001135"><em>Giraffatitan</em></a>, which stretched to a huge 12 meters – roamed modern-day Tanzania. Peeling back layers that were formed 100 million years ago in the Cretaceous in parts of North Africa yielded evidence of predatory carnivorous dinosaurs like the <a href="https://www.youtube.com/watch?v=jT8TUowrkLU"><em>Spinosaurus</em></a> (which you may recognise from the Jurassic Park films). These beasts were as big, or sometimes larger, than the famous North American <em>Tyrannosaurus rex</em>. </p>
<p>The next transition came 66 million years ago. Dinosaurs died out and <a href="https://books.google.co.za/books?isbn=0520257219">mammals diversified</a>. These mammals’ fossil records show them to be the ancestors of some of Africa’s most famous wildlife, <a href="http://www.biodiversityexplorer.org/mammals/afrotheria.htm">like elephants</a>.</p>
<p>And of course, there were humans – or there would be, eventually. The <a href="https://books.google.co.za/books?isbn=0520257219">earliest hominim fossil</a> was found in Chad; it dates back between six and seven million years. Time moved, landscapes shifted; and, 300 000 years ago, the continent’s first recorded fossil hunters emerged. Fossils and other evidence have revealed that the earliest representatives of our own species, <a href="https://www.nature.com/news/oldest-homo-sapiens-fossil-claim-rewrites-our-species-history-1.22114"><em>Homo sapiens</em></a>, collected <a href="http://www.ifrao.com/wp-content/uploads/2018/01/02Erfoud.pdf">fossil sea shells</a> in Morocco.</p>
<h2>Sharing knowledge</h2>
<p>This is but a quick glimpse into what I want my students to learn. By teaching them how amazingly rich and diverse their palaeontological heritage is, I aim to inspire this new batch of future scientists to keep studying the evolution of different species.</p>
<p>Only by educating more students about their past will academics have a chance to reach out to communities across Africa, raising awareness about the importance of the continent’s fossil heritage to us all, and ultimately give to Africa what the continent really deserves: more African palaeontologists.</p><img src="https://counter.theconversation.com/content/91849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Benoit receives funding from The Claude Leon Foundation; PAST and its Scatterlings projects; the National Research Foundation of South Africa; and the DST-NRF Centre of Excellence in Palaeosciences (CoE in Palaeosciences).</span></em></p>
You might recognise Spinosaurus, from Jurassic Park 3, but did you realise it is 100% an African dinosaur?
Julien Benoit, Postdoc in Vertebrate Palaeontology, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/72314
2017-02-16T13:43:45Z
2017-02-16T13:43:45Z
Why the discovery of a small continental fragment in the Indian Ocean matters
<figure><img src="https://images.theconversation.com/files/156935/original/image-20170215-19249-1s891ue.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mauritius beachfront view with volcanic mountains. The basaltic lavas constituting these mountains formed no older than 9 million years ago.
</span> <span class="attribution"><span class="source">Prof. Susan J. Webb, University of the Witwatersrand</span></span></figcaption></figure><p>Far beneath Mauritius’ inactive volcanoes lies an astonishing, important piece of the Earth’s history: a fragment of ancient continental crust. And no: it’s not <a href="http://www.livescience.com/23217-lost-city-of-atlantis.html">Atlantis</a>.</p>
<p>This discovery, which my colleagues and I have outlined in a newly <a href="http://rdcu.be/oVJ5">published study</a>, is extremely exciting. Discovering new pieces of continent will help geoscientists to understand the details of how continents break apart, and how the pieces can be better reconstructed to their pre-breakup configurations. This could, for example, be used as an important exploration tool for mineral deposits.</p>
<p>Our work demonstrates that continental break-up is often a complex and messy process. When continents begin to break apart, they can be stretched and fragmented, as new oceanic crust forms by continuous outpourings of magma at mid-ocean ridges. This forces the newly-formed crust to separate in opposite directions, taking the passive pieces of continent with them. Sometimes the sites of deep convection cells can suddenly shift, causing “ridge jumps”. This is how fragments of continent can become isolated, or “stranded” in many places across the ocean floor. </p>
<p>The Indian Ocean is a good place to study this, because it contains large fragments of continental crust like Madagascar, smaller ones like the Seychelles, and still smaller ones like the one now thought to underlie Mauritius.</p>
<p>Mauritius is an Indian Ocean island of volcanic origin, and lavas started forming there about 9 million years ago. Today it is dormant and most of the craters are covered with a rich variety of fauna and flora.</p>
<h2>What we found</h2>
<p>My colleagues and I suggest that during the active period, the lavas <a href="http://www.nature.com/ngeo/journal/v6/n3/abs/ngeo1736.html">erupted</a> on top of a small continental fragment that was then buried several kilometers below the new volcanic island. As the Mauritian lavas rose toward the surface, they passed through the stranded continental fragment, incorporating and dissolving some of it.</p>
<p>We were able to show that this continental fragment exists because we found tiny crystals of zircon – a mineral that can be analysed to provide age information – in a rare volcanic rock called trachyte, which is exposed at five different sites in Mauritius. We determined that the zircons were formed 2,500 to 3,000 million years ago. This is vastly older than even the earliest Mauritian volcanic rocks, which started erupting 9 million years ago. </p>
<p>The ages of the ancient zircons are also much older than the rocks present on the floor of the Indian Ocean, which all formed less than 200 million years ago. The nearest place where rocks as old as the ancient zircons can be found is in Madagascar, which is more than 700km to the west.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/o61P6ysKklM?wmode=transparent&start=94" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The ancient zircons recovered in the new research are the only accessible remnants of the old granitic rocks which are now hidden below. We cannot specify the exact size of the buried fragment of ancient continent, but we think it might be similar to the present areal extent of Mauritius, about 2000kmsq.</p>
<p>In addition to our discovery of this previously unknown continental fragment below Mauritius, my colleagues and I suggest that there may be other pieces of ancient continent scattered elsewhere on the floor of the Indian Ocean. These are now mostly submerged and covered by lavas, coral reefs or sand banks. They include the Saya de Malha Bank, the Chagos and Cargados-Carahos shoals, the Laccadive Ridge and the Nazareth Bank. They may have once been joined together 80 to 90 million years ago, in a now fragmented continent we have named “Mauritia”.</p>
<h2>Continental break up</h2>
<p>So, where did this all begin?</p>
<p>We have known for some time that the familiar continental entities of the southern hemisphere – including Africa, South America, Madagascar, India, Australia and Antarctica – were joined together about 500 million years ago. This huge landmass was called <a href="http://www.livescience.com/37285-gondwana.html">Gondwana</a>. In fact, Gondwana was once part of an even larger “super-continent” called Pangea. </p>
<p>About 185 million years ago Gondwana began to drift apart and fragment due to plate tectonic processes that take place at the Earth’s outer shell of crustal rocks. Pieces of continent, both large and small, ride as “passengers” on newly-formed plates of oceanic crust; these continuously move away from each other at speeds of several centimetres per year. </p>
<p>The familiar present-day positions of the continents will continue to change, as plate tectonic forces drive them apart. For example, continental fragmentation appears to be starting in the East African Rift of Ethiopia, Kenya and Tanzania, where a new ocean basin might form tens of millions of years in the future, splitting East and West Africa into separate continental pieces. </p>
<p>In this sense, the idea that there are only seven continents is misleading because it is arbitrarily based on size, and would exclude substantial continental entities like Greenland and Borneo, as well as smaller ones like Madagascar, New Guinea and New Zealand. Because the sizes and shapes of continents have continuously changed over time, all continental entities can therefore be considered “fragments” of variable size.</p>
<p>It isn’t every day that someone can claim to have discovered a new piece of continent, even though the one in the new work described here is buried under a volcano and cannot be seen or touched. But its presence adds to a growing understanding of how the Earth works at present, and contributes to the question of how it worked in the past. These are the primary goals of geological science.</p><img src="https://counter.theconversation.com/content/72314/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lewis Ashwal receives funding from the South African National Research Council and the University of the Witwatersrand.</span></em></p>
Researchers have found a small piece of a “lost continent” buried underneath the lava on Mauritius.
Lewis Ashwal, Professor, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/72058
2017-02-02T19:06:25Z
2017-02-02T19:06:25Z
Friday essay: the silence of Ediacara, the shadow of uranium
<figure><img src="https://images.theconversation.com/files/155075/original/image-20170131-3259-1d7av1s.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Marcoo was a 1.4 kilotonne ground-level nuclear test carried out at Maralinga in 1956. The contaminated debris was buried at this site in the 1967 clean-up known as Operation Brumby.</span> <span class="attribution"><span class="source">Author provided</span></span></figcaption></figure><p>As an archaeologist working in the remote areas around Woomera and the Nullarbor Plain, my understanding of South Australia was first informed by rocks and soil. This was a landscape of fossils and <a href="http://paleoportal.org/index.php?globalnav=fossil_gallery&sectionnav=taxon&taxon_id=109">trace fossils</a> – the preserved impressions left by the passage of a living body through sediment – jostling for attention. On this land surface, SA presents an arc extending from the “death mask” fossils of early multicellular life to the human leap into the solar system. Sure, you might say, this could be said of other locations on Earth. But here it seems laid bare for any who can read the distinctive pattern of signs.</p>
<h2>The silent shore</h2>
<p>This was once a shoreline in a silent world. Throughout some terrifying ice ages, when glaciers reached almost to the equator, microscopic single-celled creatures held on to life in the freezing oceans. As the ice sheets retreated, warmer shores opened up on the <a href="https://en.wikipedia.org/wiki/Gondwana">Gondwana supercontinent</a>, including what would later become the Flinders Ranges. Microbes swarmed together in mats to colonise the sandy sea floor. Wind and water were the only sounds, but there was nothing yet with ears to hear them.</p>
<p>The rhythm of the waves created undulations on the sea floor, to which the microbial mats cleaved. For millions of years the green ocean carpet flourished in the shallow waters. Around 635 million years ago, new forms of multicellular life appeared as additional tiers in this simple ecology. Creatures similar in appearance to fern fronds anchored themselves in the mats by a round root-like hank. Others took the form of segmented worms squashed into round pancakes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155079/original/image-20170131-3251-w7wzf7.JPG?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"></a>
<figcaption>
<span class="caption">Fossil of an Ediacaran worm.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Far from “<a href="http://www.phrases.org.uk/meanings/red-in-tooth-and-claw.html">nature red in tooth and claw</a>”, this was nature basking in the sun, in no hurry to change. Storms were the most dramatic events to occur over millions of years. The surges of water these produced would drag the button holdfast of the fronds across the sandy ocean floor, leaving a crackled trace until the wave passed and left it swaying again. In one of these storms, a sudden influx of loose sediment was dragged over some fronds, knocking them flat and covering them with silt. There was too much weight to break free and these limbless, toothless creatures had no way to burrow out.</p>
<p>Gondwana drifted, split, folded and, around 540 million years ago, uplifted, raising the ocean floor to form the slopes of a mountain range.</p>
<p>The fossilised fronds and pancake worms of the fauna from the <a href="http://www.ucmp.berkeley.edu/vendian/ediacaran.php">Ediacaran geological period</a> (635–542 million years ago) are now on display at the South Australian Museum. The ripples in the stone cast shadows that allow you to almost see the shimmering of the shallow water. The “elephant skin” texture – where the hank of a single fern frond was dragged in the storm surge – is visible in the stone, as is the wiggly path or trace fossil of a small worm that escaped burial.</p>
<p>In effect, South Australia is the trace fossil of an earlier continent, or an earlier planet – perhaps not even this one. The Ediacara fauna are vastly different to present life on Earth, and may provide an analogue for life elsewhere in the solar system.</p>
<h2>The dust giants</h2>
<p>In the <a href="http://www.livescience.com/40311-pleistocene-epoch.html">Pleistocene era</a>, starting from about 1.8 million years ago, the ice sheets advanced again. With so much water locked away in the ice, vast plains were exposed on the continental shelf. Plant communities died off and soil formation slowed as temperatures and rainfall decreased. No longer consolidated by vegetation, sediments were blown away in the cold winds. <em>Aeolian</em> is the word, like a harp with a dry rustling sound. The sand traversed huge distances and settled into waves of dunes reflecting the wind direction. The leaching of iron stained their quartz sands Martian-red.</p>
<p>Low saltbushes and bluebushes were studded across the dunes at the edge of the ranges, with occasional forests of large saltbush. Giant kangaroos, three metres high, were as tall as these forest canopies. They loped along the dunes with their smaller cousins, sometimes venturing to the open grasslands that stretched to the distant coast of Sahul.</p>
<p>The carnivore <em><a href="https://australianmuseum.net.au/thylacoleo-carnifex">Thylacoleo carnifex</a></em> roamed the plains, stalking <em><a href="https://australianmuseum.net.au/palorchestes-azeal">Palorchestes azael</a></em> and other herbivores. Waterholes were perilous places where the giant snake <em><a href="http://www.prehistoric-wildlife.com/species/w/wonambi.html">Wonambi naracoortensis</a></em> coiled in wait. Taking shelter from the cold wind in a limestone cave, Aboriginal people might have looked out to see the huge shadows of a herd of <a href="https://en.wikipedia.org/wiki/Diprotodon">diprotodons</a>, the marsupial “rhinoceros”, or <em><a href="https://theconversation.com/a-case-of-mistaken-identity-for-australias-extinct-big-bird-52856">Genyornis</a></em>, the two-metre-tall flightless bird. If these animals were reptiles, we would call them dinosaurs.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155266/original/image-20170201-29911-m4jdoj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wallaby skin water carrier.</span>
<span class="attribution"><span class="source">Stuart Humphreys © Australian Museum</span></span>
</figcaption>
</figure>
<p>At the height of this cold, dry period – 30-19,000 years ago – a person might have seen the ocean only a few times across their lifespan. A nacreous abalone shell, excavated at <a href="https://www.academia.edu/27094779/A_Technological_Analysis_of_Stone_Artefacts_from_Allens_Cave_South_Australia_Thesis_Abstract_2016">Allen’s Cave</a> on the Nullarbor Plain and dated to 18,000 years ago, speaks of a journey hundreds of kilometres overland to the shore. Specialist knowledge was needed to travel far from permanent or regular water sources: how to find water-bearing roots, rock wells, and Artesian springs. Perhaps more was needed too: <a href="https://australianmuseum.net.au/wallaby-skin-water-carrier-pre-1885">kangaroo-skin water bags</a>, the endurance to carry a coolamon of water for miles without spilling a drop. The desert sands and the porous limestones of the Nullarbor don’t hold water reservoirs, and the aridity turned the lakes to the west and north of the Flinders Ranges into salt.</p>
<p>Aboriginal people would have noted but passed over the sedimentary rocks that preserved the Ediacara fauna. Instead, they searched for <a href="https://www.mindat.org/min-960.html">chalcedony</a>, <a href="https://www.mindat.org/min-994.html">chert</a>, and <a href="https://en.wikipedia.org/wiki/Silcrete">silcrete</a>. With an understanding of how these stones fracture, you can make a cutting edge sharper and more sterile than a metal surgical blade. Glassy veins of such stone, nacreous in their own way, occur throughout the Nullarbor plain.</p>
<p>Countless scholarly papers describe the climatic conditions and biological record of the <a href="https://en.wikipedia.org/wiki/Last_Glacial_Maximum">Last Glacial Maximum</a>. Between the lines of these papers we can catch a glimpse of how Aboriginal people may have experienced these landscapes. In the field, I look for traces of their life where the red dunes are exposed – a stone tool or the ashes of a hearth, perhaps. Mining companies, however, would mostly prefer these traces vanished.</p>
<h2>A line in the sand</h2>
<p>The ice melted again, and water inundated the great coastal plains. The megafauna were long gone, leaving the regular kangaroos, emus and wombats behind to compete with new migrants: sheep, cattle, camels and rabbits. The livestock, particularly cattle, thrived on saltbush.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=866&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=866&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=866&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1089&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1089&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155082/original/image-20170131-3274-18q8gdx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1089&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">George Goyder.</span>
<span class="attribution"><span class="source">Wikimedia commons</span></span>
</figcaption>
</figure>
<p>It was still arid out in the north and centre, though droughts lasted just a few years instead of thousands. The years 1863–66 were particularly severe. The Surveyor-General of SA, <a href="http://adb.anu.edu.au/biography/goyder-george-woodroffe-3647">George Goyder</a>, was sent out in 1865 to define the area where reliable rainfall divided agricultural from grazing land. In the absence of rainfall records, he observed geology and vegetation to create a line stretching over 3000 kilometres, from Pinaroo on the Victorian border to Ceduna in the far west. South of the line was dominated by mallee scrubs, and the north by saltbush and other chenopods.</p>
<p>A few years later, seasons had improved. The bold bought land above the <a href="https://en.wikipedia.org/wiki/Goyder's_Line">Goyder Line</a> for cropping. This line was not, however, just a mark on a map; as successive drought oscillations continued, farmers were forced back south, abandoning homesteads and even whole towns, the crumbling remains of which are still visible today.</p>
<p>In the process of settlement, trees were cut down for fence posts, telegraph poles and firewood. On the treeless Nullarbor Plain, soil was stabilised by delicate <a href="http://www.soilcrust.org/crust101.htm">biological crusts</a> formed from lichens and bacteria. The hard hoofs of the livestock cracked them like the toffee shell on a crème brûlée, and the dust blew again.</p>
<p>In 1945, the CSIRO scientist RW Jessup was sent to investigate soil erosion in arid areas of South Australia. He noted the degeneration caused by the combined effect of rabbits and stock. When rabbits reached plague proportions and began to run out of food, they ate the young shoots and ringbarked trees. Fast growing species could bounce back, but slower trees like mulga and myall suffered the most, especially in the absence of Aboriginal firing regimes to germinate seeds. Jessup noticed the Precambrian rocks but did not stop to look for fossils. He was more focused on the windblown sands: evidence of how pastoralism was recreating the arid conditions of the Pleistocene.</p>
<p>The same year saw the end of the Second World War. Far away in another hemisphere, a <a href="http://www.smithsonianmag.com/arts-culture/wernher-von-brauns-v-2-rocket-12609128/">rocket capable of reaching outer space</a> had been built and <a href="http://www.atomicheritage.org/history/bombings-hiroshima-and-nagasaki-1945">two atomic bombs deployed</a>. These events would shape the world for decades to come, and leave their imprint in the outback of South Australia.</p>
<h2>Uranium and rockets</h2>
<p>In 1946, there were many people roaming the South Australian deserts. One was geologist <a href="https://en.wikipedia.org/wiki/Reg_Sprigg">Reg Sprigg</a>, searching for uranium to supply the growing demand for nuclear weapons. He started with the old <a href="https://en.wikipedia.org/wiki/Radium_Hill">Radium Hill</a> mine in the east, and surveyed Mount Painter in the Flinders Ranges, before coming to the Ediacara Hills in the north of the ranges. On the gentle slopes, he was struck by ancient sandstone slabs, generally a poor type of stone for fossil preservation. But he’d seen fossils in this sort of rock before. The round impressions that he saw looked like flattened jellyfish and large segmented worms, but the rock was clearly Precambrian – an age when only single-celled animals were supposed to exist.</p>
<p>The discovery was initially received with scepticism. Some argued that the shapes were natural phenomena. Others disputed the dates. It wasn’t until the discovery of similar fossils in Namibia, Siberia and other locations, and the support of some University of Adelaide academics, that the Ediacara fauna were acknowledged to be genuine. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=779&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=779&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=779&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=979&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=979&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155084/original/image-20170201-3265-13oq03n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=979&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Spriggina fossil.</span>
<span class="attribution"><span class="source">Wikimedia commons</span></span>
</figcaption>
</figure>
<p>The creatures then received names. <em><a href="http://paleoexhibit.blogspot.com.au/2015/02/dickinsonia-from-ediacaran-biota.html">Dickinsonia</a></em> was the flat pancake worm. The jellyfish turned out to be mostly the discoid holdfast of the frond-shaped <a href="https://museumvictoria.com.au/melbournemuseum/discoverycentre/600-million-years/timeline/ediacaran/charnia/">Charnia</a>. Reg Sprigg lent his name to the mysterious segmented <em><a href="https://en.wikipedia.org/wiki/Spriggina">Spriggina</a></em> species – maybe a worm, maybe a frond, maybe something like the later trilobites. </p>
<p>While Reg Sprigg continued his search for uranium deposits, men from the Army’s Survey Corps were on the gibber plains around Mount Eba, mapping an area the size of England to enclose a <a href="https://en.wikipedia.org/wiki/Woomera_Test_Range">rocket test range</a>. The Anglo-Australian Joint Project was established to develop weapons for Britain, and Australia hoped, through this arrangement, to gain a greater defence capacity to fend off Asia. The German V-2 rocket, which had devastated London in the last months of the war, would form the basis of this new weapon system.</p>
<p>Senior British military personnel took a flight to see the proposed area for themselves. They flew over the Central Aborigines Reserve on the borders between South and Western Australia, the direction in which the future rockets would be launched. To their eyes, the red desert recalled another: the white sands around the <a href="http://www.atlasobscura.com/places/trinity-atomic-bomb-site">Trinity site in New Mexico</a>, USA, where the first atom bomb was exploded in 1944. The Australian author <a href="https://en.wikipedia.org/wiki/Ivan_Southall">Ivan Southall</a> described this view later in 1962: </p>
<blockquote>
<p>Here it was, one of the greatest stretches of uninhabited wasteland on earth, created by God specifically for rockets.</p>
</blockquote>
<h2>Hidden in plain sight</h2>
<p>Aboriginal people became a trace fossil in the land deemed empty – hidden in plain sight. <a href="http://www.kokatha.com.au/">Kokatha</a>, <a href="https://en.wikipedia.org/wiki/Pitjantjatjara">Pitjantjatjara</a>, <a href="http://nativetitle.org.au/profiles/profile_sa_adnyamathanha.html">Adnyamathanha</a> and <a href="https://en.wikipedia.org/wiki/Barngarla_people">Barngarla</a> people lived on missions around the state, and gathered in coastal towns that offered them the employment that the rocket range had promised but didn’t deliver.</p>
<p>At this time, white Australians thought Aboriginal occupation had been a few thousand years at most, and many believed Aboriginal people were dying out – the inevitable result of the “stone age” being superseded by the “space age”.</p>
<p>Ironically, it would take American chemist <a href="https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1960/libby-bio.html">Willard Libby’s</a> invention of radiocarbon dating in the 1940s – an idea that came to him when working on the atomic bomb for the <a href="http://www.amnh.org/exhibitions/einstein/peace-and-war/the-manhattan-project/">Manhattan Project</a> – to establish the much deeper antiquity of occupation. <a href="http://www.anu.edu.au/news/all-news/vale-emeritus-professor-john-mulvaney">John Mulvaney’s</a> 1962 excavation of Kenniff Cave in Queensland used radiocarbon to obtain a date of 19,000 years ago, during the Last Glacial Maximum.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=957&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=957&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=957&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1203&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1203&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155078/original/image-20170131-3279-gjdmlr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1203&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Black Arrow rocket, Woomera.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>In 1947, on the first reconnaissance for a place to build the township that would service the rocket range, surveyors found tens of thousands of stone tools at Phillip Ponds. Recognising that evidence of Aboriginal occupation also meant the presence of water, they selected this location for the <a href="http://homepage.powerup.com.au/%7Ewoomera/town.htm">Woomera Village</a>, named after the wooden spear-thrower used by Aboriginal people in many parts of Australia. The street names in the new town were sourced from a vocabulary compiled by HM Cooper, published in 1948 as <a href="http://digital.slv.vic.gov.au/view/action/singleViewer.do?dvs=1485930873895%7E603&locale=en_US&metadata_object_ratio=10&show_metadata=true&VIEWER_URL=/view/action/singleViewer.do?&preferred_usage_type=VIEW_MAIN&DELIVERY_RULE_ID=10&frameId=1&usePid1=true&usePid2=true">Australian Aboriginal Words and Their Meanings</a>.</p>
<p>In the following decades, Australian scientists designed sounding rockets for upper atmosphere research and worked on British long-range ballistic missiles like the <a href="http://www.armaghplanet.com/blog/blue-streak-uks-cold-war-rocket.html">Blue Streak</a>. They also collaborated with the US in establishing another new technology: tracking the satellites that were planned for launch in the <a href="http://www.nas.edu/history/igy/">International Geophysical Year</a> of 1957–58. In 1957, the world’s first satellite, Sputnik 1, sent its distinctive beep into the ether. The Space Age had begun.</p>
<h2>Radioactive</h2>
<p>My trips to the <a href="http://www.defence.gov.au/woomera/about.htm">Woomera Prohibited Area</a> are sometimes to advise mining companies about heritage issues, and sometimes to do my own research on Australia’s space program. One day, I’m taken out to the derelict structures once used as launch pads for a unique hybrid rocket.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/pvcHO4WieV0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The satellite launcher <a href="https://en.wikipedia.org/wiki/Europa_(rocket)">Europa</a> was a collaboration between six European nations and Australia in the early 1960s. The two launch pads stand on the edge of a blindingly white salt lake. Rock art sites can be found on outcrops and boulders around the lower edge of the steep shores. Against the wind, I imagine the tremendous roar of the rocket’s engines and think of Ivan Southall’s description of the landscape in his 1962 book, Woomera:</p>
<blockquote>
<p>It’s almost like you are living in another world, just as though you had been shot off in a spaceship and let down on some strange planet where men had never been before.</p>
</blockquote>
<p>Writing about Woomera and Maralinga, Southall constantly emphasises the silence of a landscape where, he avers, even Aboriginal people speak in undertones. This seems supremely ironic when you think of rocket engines roaring, or the more sinister blast of an atom bomb. From 1956 to 1963, Australia supported Britain in <a href="https://en.wikipedia.org/wiki/British_nuclear_tests_at_Maralinga">a series of nuclear tests</a> at two locations outside Woomera’s perimeter, Maralinga and Emu Field. Southall visited Emu Field in 1962 where</p>
<blockquote>
<p>sprayed with yellow paint, and silent in the sand, are abandoned trucks and jeeps and weapons once too hot to handle. There, near the bomb towers that vanished, the very surface of the desert has become as glass.</p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155072/original/image-20170131-3244-j4qjj0.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">Green-tinged nuclear glass at Maralinga.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>The vitrified sand is the same iron oxide-coated sediment of the Pleistocene aeolian dunes, now with a greenish tinge like a cheap wine bottle. Such nuclear glass is highly collectible, and is sometimes called trinitite after the glass from the Trinity site in New Mexico.</p>
<p>The resonances of these tests aren’t fading any time soon. Generations of Aboriginal people and white Australians still suffer the effects of exposure to radiation. The shadows of the radioactive fallout – the “black mist”, as many Aboriginal people call it – are almost inescapable when you travel west in this state.</p>
<p>At Woomera, I go to look at the grave monuments in the cemetery on the hill outside the town. There are multiple still births and infant deaths, often in the same family. People don’t like to talk about it, but there are stories of women wailing in the streets, driven by unassuagable grief. A local urban myth held that if a pregnant woman stood on the hill facing Maralinga during a bomb test, the sex of the foetus would be revealed in x-ray silhouette.</p>
<p>On the far west coast we’re walking through the saltbush and tyre-piercing bluebush to a rock hole, where some of the traditional owners want to carry out maintenance by clearing the accumulated weeds and dirt. On our way we pass an unusual farm shed. It’s made of radiation-proof lead, scavenged from Maralinga by the landowner. I learn that such scavenging has distributed the artefacts of rockets and bombs all over the state.</p>
<p>On another day, the women are driving up the Ooldea track towards the <a href="https://en.wikipedia.org/wiki/Trans-Australian_Railway">transcontinental railway line</a>. One roasted a wombat the night before and distributes chunks to us. As we gnaw on the bones, the women point out campsites off to the side of the track. You can’t necessarily see anything from the road, but the locations are loaded with memory. These are places where they camped during the trek from the Maralinga lands down to the coast. It wasn’t safe to stay, but leaving creates its own devastation.</p>
<p>Finally, I’m here at Maralinga. Despite four phases of remediation, there is so much to catch the archaeologist’s eye. No doubt the last people in white radiation suits to leave the site after the 2000 <a href="https://industry.gov.au/resource/Documents/radioactive_waste/martac_report.pdf">clean-up</a> thought all the residues of the hot yellow machines and bomb towers were safely interred in the burial mounds. I’m used to working at the scale of stone tools, though, and find the surface is scattered with small artefacts like broken ceramics and beer cans. </p>
<p>What really sticks in my memory are ephemeral traces of human presence. Along the wire of a perimeter fence, someone has looped bits of metal and twist ties in a line. A square grid has been drawn in the gravel near a radio tower. The tyre tracks of earth-moving machinery around and over the large burial mounds make me think of rover tracks on Mars.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155071/original/image-20170131-3269-1meucf2.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">Decorated fence at Maralinga.</span>
<span class="attribution"><span class="source">author provided</span></span>
</figcaption>
</figure>
<p>This land is already a nuclear waste dump. The locations and proposals change, but the same apparent “emptiness” that brought rockets, nuclear tests and detention centres now attracts commercial interest in storing nuclear waste from other nations. It’s the end of a cycle that starts with the mining and export of Australian uranium. The redistribution of uranium is a very <a href="https://quaternary.stratigraphy.org/workinggroups/anthropocene/">Anthropocene</a> process, part of the dismantling and reassembling of the planet.</p>
<p>In the end it will all be buried, all become an archaeological site. Long after the molecular structure of the human-made materials has broken down, the uranium and plutonium will still be decaying. Future archaeologists may find it difficult to determine if these radioactive deposits are natural or cultural. Maybe the distinction will be irrelevant.</p>
<h2>Epilogue: the wind</h2>
<p>The story isn’t quite over yet, though. The Ediacara fauna gave their name to a new geological period, and while their relationship with contemporary species is still hotly debated, they have changed the way life on Earth is viewed.</p>
<p>The megafauna had largely disappeared by 10,000 years ago. The role of Aboriginal people in their extinction is also hotly debated, though archaeological evidence does not support the “overkill” hypothesis. New genetic studies are now pushing back the date of Aboriginal arrival in Australia to more than 60,000 years ago.</p>
<p>The Goyder Line is <a href="http://www.abc.net.au/news/2015-12-02/goyders-line-climate-change-wheat-wine-grapes/6919276">shifting south</a> under the impacts of climate change.</p>
<p>Reg Sprigg, who died in 2008, established the Arkaroola Sanctuary in the Flinders Ranges. The Mars Society of Australia selected it as their primary <a href="http://www.abc.net.au/science/articles/2004/03/23/1071845.htm">Mars analogue landscape</a> to pursue both planetary science and practical aspects of Mars colonisation.</p>
<p>After becoming the fourth nation in space with the launch of the <a href="http://homepage.powerup.com.au/%7Ewoomera/wresat.htm">WRESAT-1 satellite</a> in 1967, Australia’s ambitions have languished. Woomera is still a busy test range, but we are no longer at the forefront of space exploration.</p>
<p>Maralinga has been handed back to its traditional owners. You can visit as a tourist.</p>
<p>The wind has been a constant theme. Once the dominant sound in the Ediacaran world, now it drives giant wind turbines supplying power to the state.</p>
<p>One planet’s past may be another’s future. The Ediacarans have vanished from South Australia, but deep time is always waiting to burst through the crusts of the surface. In the words of Ivan Southall:</p>
<blockquote>
<p>In the most barren regions, the most lifeless regions, strange things happen after rain. Primitive crustaceans suddenly stir in the saline mud, reminding one of the dawning of time.</p>
</blockquote>
<hr>
<p><em>This essay first appeared in Griffith Review State of Hope, the 55th edition of Griffith Review.</em></p>
<p><em>The author thanks Hilda Moodoo, Wanda Miller, Eileen Wingfield, Andrew Starkey and many others who have generously shared their knowledge.</em></p><img src="https://counter.theconversation.com/content/72058/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alice Gorman is a member of the Advisory Council of the Space Industry Association of Australia and the Alternate State Delegate for the South Australian Chapter of the Australian Association of Consulting Archaeologists Inc</span></em></p>
History is writ large in the remote areas around Woomera and the Nullarbor: from the fossils of microscopic, cell-like creatures to ancient stone tools to the deitrus of rocket tests and the painful legacy of the Maralinga atomic blasts.
Alice Gorman, Associate Professor in Archaeology and Space Studies, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/67383
2016-10-20T22:17:05Z
2016-10-20T22:17:05Z
Meet Savannasaurus, Australia’s newest titanosaur
<figure><img src="https://images.theconversation.com/files/142472/original/image-20161020-8852-1gc9g2j.png?ixlib=rb-1.1.0&rect=10%2C10%2C2340%2C1651&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Savannasaurus was pretty small, by titanosaur standards</span> <span class="attribution"><span class="source">Travis Tischler/Australian Age of Dinosaurs Museum of Natural History</span></span></figcaption></figure><p>The outback region around Winton in central Queensland is arguably Australia’s ground zero for giant dinosaur fossils. Here, graziers occasionally stumble across petrified bones on their paddocks, amid the stubbly grass and cow dung. </p>
<p>These bones appear like the living dead, rising from the underworld by an unusual process whereby the wetting and drying of the clay-rich soil works like a convection current, slowing bringing rocks and sometimes fossils to the surface. In the past, these stray bones would have been picked up and slung into the back of a ute, leaving researchers wondering what became of the rest of the animal. </p>
<p>In recent years, researchers from the <a href="http://www.australianageofdinosaurs.com/">Australian Age of Dinosaurs Museum (AAOD)</a> in Winton have been returning to some of these old sites, and finding dozens of new ones with the help of bulldozers. They have been digging down through the deep soil to the bedrock below – the source of these fossil relics.</p>
<p>Their unconventional methods have proved incredibly fruitful. In 2009, palaeontologist Scott Hocknull and a team from the Queensland Museum and the AAOD <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006190">named three new species of dinosaur</a>: the long-necked sauropods Diamantinasaurus and Wintonotitan, and a huge predatory dinosaur, Australovenator. </p>
<p>Since then, another palaeontologist working with the AAOD, Steven Poropat, has been dodging the bulldozer’s blade and watching keenly during the early stages of each excavation for the telltale glint of bone among the freshly exposed rocks before it is crushed by the dozer’s tracks.</p>
<h2>Savannasaurus, the little titanosaur</h2>
<p>Enter Savannasaurus, Australia’s newest face in the world of dinosaurs, a long-necked plant-eater <a href="https://dx.doi.org/10.1038/srep34467">named by Poropat and his team today in the journal Scientific Reports</a>. The new skeleton includes most of the vertebrae from the back, parts of the hips, forelimb and a scattering of ribs, foot bones, neck and tail vertebrae. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/142474/original/image-20161020-8828-ve2qjc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stephen Poropat with some of Savannasaurus’s vertebrae.</span>
<span class="attribution"><span class="source">Judy Elliott/Australian Age of Dinosaurs Museum of Natural History</span></span>
</figcaption>
</figure>
<p>It was a fairly small animal as far as sauropods are concerned, perhaps measuring around 12-15m long based on the published drawings, but belongs to a group known ominously as the titanosaurs, which were most common in Asia and South America.</p>
<p>Poropat and his team also found further remains of Diamantinasaurus, which included part of its skull – the first sauropod skull unearthed in Australia. Together, the new fossils show that these two species were closely related within the titanosaur family. </p>
<p>Based on the timing of the <a href="http://homepages.see.leeds.ac.uk/%7Eeargah/Gond.html">breakup of the Gondwanan supercontinent</a>, Poporat and his colleagues believe that Savannasaurus’ titanosaur ancestors probably made their one-way trek to Australia from South America via Antarctia during the mid-Cretaceous, some 105–100 million years ago. </p>
<p>The similarities between South America’s and Australia’s dinosaurs have been recognised before. In fact, <a href="http://www.sciencedirect.com/science/article/pii/S1342937X15002026">my own research</a> has found evidence that Australia may have bequeathed to South America its own cohort of carnivorous dinosaurs – a group called the megaraptorids, of which Australovenator was a member. </p>
<p>Exactly how and when they arrived is somewhat contentious. Given the general paucity of Australian dinosaur fossils as a whole, the final word is still out regarding who begat whom. One of the major hindrances faced by Australian palaeontologists is the limited timeframe in which their fossils are found. The most productive dinosaur localities in Australia are clustered between 115 million and 100 million years old; spanning a mere 10% of the known time that dinosaurs ruled the Earth. </p>
<p>What happened before and after this time slice is very poorly understood. Poropat and his team, as they put it, provide a framework within which new discoveries can be assessed. We’ve got a long way to go, but then again, science can only move forward once the first step is taken.</p><img src="https://counter.theconversation.com/content/67383/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phil Bell receives funding from National Geographic. </span></em></p>
Dinosaur bones unearthed at one of Australia’s richest fossil sites have introduced us to a new species: Savannasaurus, one of a family of huge dinosaurs that trekked here more than 100 million years ago.
Phil Bell, Palaeontologist, Earth Science Faculty, University of New England
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/54885
2016-02-18T03:45:39Z
2016-02-18T03:45:39Z
Australia’s south west: a hotspot for wildlife and plants that deserves World Heritage status
<figure><img src="https://images.theconversation.com/files/111733/original/image-20160217-19239-a5j1b3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The numbat, Australia's equivalent of a meerkat, is one of the unique mammal species confined to the south west. </span> <span class="attribution"><span class="source">Sean Van Alphen</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Southwest Australia is one of 25 original <a href="http://www.nature.com/nature/journal/v403/n6772/full/403853a0.html">global hotspots for wildlife and plants</a>, and the first one identified in Australia. </p>
<p>Since the first analysis identifying biodiversity hotspots in 2000, the list has expanded, and now 35 hotspots are recognised, two in Australia: the Southwest and the <a href="http://link.springer.com/chapter/10.1007%2F978-3-642-20992-5_16">forests of east Australia</a>. </p>
<p>Biodiversity hotspots are defined as regions “where exceptional concentrations of endemic species are undergoing exceptional loss of habitat”. As many as 44% of all species of native plants and 35% of all species in four animal groups are confined to the original 25 hotspots, which comprise only 1.4% of Earth’s land surface. </p>
<p>This opens the way for a <a href="http://www.nature.com/nature/journal/v403/n6772/full/403853a0.html">conservation strategy</a>, focusing on these hotspots in proportion to their share of the world’s species at risk.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=332&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=332&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=332&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=417&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=417&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111737/original/image-20160217-19241-1ijm2fa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=417&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Kwongan with national parks, reserves and other conservation aras marked in blue.</span>
</figcaption>
</figure>
<h2>Introducing the south west</h2>
<p>Australia was once part of the <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2699.2011.02546.x/abstract">ancient continent Gondwana</a>, which began to break up more than 154 million years ago. The region that supports the Southwest’s unique wildlife formed when India broke away from the supercontinent around 120 million years ago. While there are some young sand dunes, much of the southwest has been geologically undisturbed for tens of millions of years. </p>
<p>Southwest Australia, also known as the Kwongan, is therefore an <a href="http://www.web.uwa.edu.au/__data/assets/pdf_file/0017/612161/Hopper_2009_OCBIL_theory.pdf">old landscape with a stable climate</a>. It has not seen glaciers or ice for more than 200 million years. This has allowed species to evolve without the major extinctions seen elsewhere in the world. </p>
<p>The region is about the size of England. England has about 1,500 species of vascular plants (all plants except ferns and mosses), 47 of them found nowhere else.</p>
<p>Contrast that with Southwest Australia, which harbours an astonishing <a href="http://uwap.uwa.edu.au/products/plant-life-on-the-sandplains-in-southwest-australia-a-global-biodiversity-hotspot">7,239 vascular plant species</a>, almost 80% of which are found nowhere else in the world. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111736/original/image-20160217-19269-1ue3lld.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Kingia australis</em> is completely unique to the south west.</span>
<span class="attribution"><span class="source">Graham Zemunik</span></span>
</figcaption>
</figure>
<p>Among these unique species is <em>Cephalotus follicularis</em>, the Albany pitcher plant, a carnivorous species that belongs to its own family and is not at all related to other carnivorous pitchers. </p>
<p>Another iconic endemic is <em>Kingia australis</em>, a single species in an Order found nowhere else (to put this in context, an Order is the same same level of classification as all butterflies and moths). </p>
<p>There are fewer animals in the south west than plants, but the Kwongan is home to some of Australia’s most iconic species, such as the tiny nectar and pollen-feeding Honey possum (<em>Tarsipes rostratus</em>). The Honey possum is only distantly-related to other Australian marsupials and is the only member of its Family. Some DNA studies also place it close to a small South American marsupial, the Monito del Monte (<em>Dromiciops gliroides</em>), suggesting a link between its ancestor and the time when South America was joined to Gondwana. </p>
<p>Another amazing marsupial found exclusively in the Kwongan is the termite-eating numbat (<em>Myrmecobius fasciatus</em>), the only truly diurnal marsupial with sentinel behaviour similar to that of the African meerkat. </p>
<p>The <a href="https://theconversation.com/australian-endangered-species-woylie-19448">Brush-tailed bettong or Woylie</a> (<em>Bettongia penicillata</em>) was until recently very abundant in the south west but, starting in 2006, it has suffered a <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9482446&fileId=S0030605313000677">dramatic decline</a> and is now currently listed as Critically Endangered. Nobody knows why. This underlines the critical need for protection of these unique species and their habitat in a biodiversity hotspot under increasing pressure from urbanisation.</p>
<p>Due to its ancient geology, the soils in the region are almost all <a href="http://science.sciencemag.org/content/345/6204/1602">poor in nutrients</a>, but this is likely the secret to the south west’s astonishing diversity. Like most of Australia, the region has been inhabited by humans for well over 40,000 years, so that a rich cultural heritage adds to the biological and geological value of the region.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111741/original/image-20160217-19256-1882cm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&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 honey possum’s closest relative may be in South America, indicating ancient connections.</span>
</figcaption>
</figure>
<h2>Of poison and plants</h2>
<p>What are the threats for the Southwest Australian hotspot?</p>
<p>For small animals, these threats are predominantly feral cats, foxes and other introduced mammals. The main method to control these is by using sodium fluoroacetate, commonly known as 1080. </p>
<p>Introduced animals are highly-sensitive to this poison, which blocks their metabolism. Native animals in south-western Australia have co-evolved with Gastrolobium (a type of pea flower) species, which produce and contain fluoroacetate. The native wildlife is therefore relatively <a href="http://uwap.uwa.edu.au/products/plant-life-on-the-sandplains-in-southwest-australia-a-global-biodiversity-hotspot">immune to 1080</a>. </p>
<p>Plants known to produce fluoroacetate are rare. Outside the genus <em>Gastrolobium</em>, the trait is known for one Acacia species in Australia, a single genus in Africa and three genera in Brazil. </p>
<p>Baiting with 1080 is expensive and some animal rights supporters object to it on the grounds that it is not humane. Fencing is an excellent alternative, and used by the Australian Wildlife Conservancy. It is expensive in the short term, but may actually be a better option in the long run.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=897&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=897&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=897&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1127&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1127&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111740/original/image-20160217-19232-p1epz0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1127&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 looks like a pitcher plant, but <em>Cephalotus follicularis</em> isn’t closely related at all.</span>
<span class="attribution"><span class="source">Hans Lambers</span></span>
</figcaption>
</figure>
<p><a href="https://www.researchgate.net/publication/260312133_Conservation_of_the_kwongan_flora_threats_and_challenges">Threats to plants</a> have historically been land clearing for agriculture. Not only did this remove the original vegetation, including endemic species, but it also gave rise to dryland salinity, as a result of a rising saline water table.</p>
<p>Salt that arrived from the ocean with the rain has accumulated in the landscape, but low in the soil profile. When perennial vegetation was replaced by annual crops that use far less water on an annual basis, the saline water table rose. This gave rise to expanding salt lakes, which are a natural element in south-western Australia, as well as new salt lakes and salt scars in the landscape.</p>
<p>A more recent threat to the biodiversity hotspot is the massive development for housing and recreation that has grown in the southwest region of Western Australia. This brings with it weed invasions, higher incidence of animal road deaths due to cars and trucks, and habitat destruction due to more frequent bushfires. </p>
<p>A 2011 bushfire caused by a prescribed burn in the Margaret River region resulted in the death of large numbers of now endangered Western ringtail possums and the destruction of many houses. </p>
<p>Australian vegetation has a long history of exposure to and resilience in the face of fire, but an <a href="http://www.ncbi.nlm.nih.gov/pubmed/21095155">increase in fires due to climate change</a> may overwhelm native wildlife and plants. </p>
<h2>Protecting the Southwest, forever</h2>
<p>Lack of knowledge among the local community of the amazing diversity of the southwest is one of the reasons it is not cared for as well as it should be. So we founded the <a href="http://www.plants.uwa.edu.au/alumni/kwongan">Kwongan Foundation</a> in 2006 with a view to conserving the south west and promoting research. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=733&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=733&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=733&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=922&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=922&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111739/original/image-20160217-19260-hdj3fl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=922&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Woylie have inexplicably declined since 2006.</span>
<span class="attribution"><span class="source">Mark Bundock</span></span>
</figcaption>
</figure>
<p>Our main aim is to secure UNESCO World Heritage Listing for the entire Southwest Australian Biodiversity Hotspot, focusing on national parks and existing reserves, without impinging on farming, forestry and mining activities. </p>
<p>UNESCO inscription would raise local awareness, offer better protection, and boost the tourism industry, which is worth billions to the state, with the “nature experience” one of the top drawcards for foreign visitors. </p>
<p>Tourism is not far behind the mining industry as an income-generating economic activity. Ecology and economy can therefore go hand in hand, leading to diversification of the Western Australian economy. </p>
<p>We’re hoping any WA minister for the environment or tourism will embrace the plan and wish to own it, as well as scientists. One thing is certain, without action soon, Australia’s most important biodiversity hotspot will be gone forever.</p>
<p><em>To find out more about the South West’s unique biodiversity see the <a href="http://uwap.uwa.edu.au/products/plant-life-on-the-sandplains-in-southwest-australia-a-global-biodiversity-hotspot">Plant Life on the Sandplains in Southwest Australia</a> and the Kwongan Foundation on <a href="https://www.facebook.com/kwonganfoundation/">Facebook</a>.</em></p><img src="https://counter.theconversation.com/content/54885/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hans Lambers is the founder and patron of the Kwongan Foundation. </span></em></p><p class="fine-print"><em><span>Don Bradshaw 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>
South west Australia is home to an astonishing number of plants and some of the country’s weirdest wildlife. Now we need to protect it.
Hans Lambers, Professor and Head of School, The University of Western Australia
Don Bradshaw, Emeritus professor, The University of Western Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/43926
2015-07-15T04:34:33Z
2015-07-15T04:34:33Z
Ancient plant eating cousins from Brazil and South Africa are reunited
<figure><img src="https://images.theconversation.com/files/87382/original/image-20150704-20468-dfudj7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artistic reconstruction of two Tiarajudens males during combat in the Permian of southern Brazil.</span> <span class="attribution"><span class="source">Supplied</span></span></figcaption></figure><p>New <a href="http://rsos.royalsocietypublishing.org/">evidence</a> has been provided confirming previous <a href="http://www.nature.com/news/earth-science-how-plate-tectonics-clicked-1.13655">compelling</a> geological findings that today’s continents were once linked in one giant land mass. The evidence has come through the discovery that two fossils, one from South Africa and the other from Brazil, were cousins.</p>
<p>The discovery of a Brazilian plant-eating herbivore fossil in 2008 prompted a restudy of the South African cousin of the same size and with a remarkably similar skull discovered 10 years earlier. These two species from <a href="http://www.livescience.com/37285-gondwana.html">Gondwana</a> – the ancient super continent formed by now separated southern continents such as Africa and South America – show features in their skull and teeth that indicate they were closely related.</p>
<p>Close examination of the two skulls, identified as four-legged or tetrapod animals that date back to a time before dinosaurs existed, revealed two further astonishing facts. The first is that 270 million years ago they were already capable of chewing their food like modern ruminants such as cattle, sheep, goats and deer. </p>
<p>The fossils, which date from what is known as the Middle Permian period, also show that the plant-eating tetrapods had developed two specialisations that they used in combat – a feature typical of today’s cows and deer.</p>
<p>And the most fascinating aspect of all is that these not too distant cousins were found more than 8000 kilometres apart on different modern day continents.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=297&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=297&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=297&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=373&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=373&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87380/original/image-20150704-20484-1hc0qj2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=373&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The skulls of Anomocephalus africanus (left) and Tiarajudens eccentricus (right).</span>
<span class="attribution"><span class="source">Supplied.</span></span>
</figcaption>
</figure>
<h2>The deers of yesteryear</h2>
<p>Living mammals have a rich history documented by fossils going back 300 million years. Ancestral lineages of mammals were included in a group known as <a href="http://global.britannica.com/animal/therapsid">therapsids</a> that flourished during the <a href="http://www.ucmp.berkeley.edu/permian/permian.php">Permian</a>, which predated the age of dinosaurs, and are exquisitely documented in the Karoo Basin of South Africa.</p>
<p>Plant-eating animals are now far more diverse and abundant than carnivores, a trend that began during the Permian. A particular group called anomodonts can best be described as the “Permian deers”. Besides being plant-eating and the most abundant lineage of the Permian, anomodonts were extremely variable in size. They were also very different in their shapes, particularly the earliest members of the group.</p>
<p>The Brazilian fossil had some unexpected features for a herbivore. Three stand out. The first is that it had occluding teeth that allowed them to chew, or masticate, food – a feature that is a landmark of today’s mammals.</p>
<p>The second is that it had a long outsized blade-like canine (~120 mm long). This shows, for the first time, the presence of saber-tooth in herbivores mammals around 270 million years ago. Saber teeth are found in some great carnivores from the past such as the <a href="http://www.ucmp.berkeley.edu/synapsids/gorgonopsia.html">gorgonopsians</a> or the <a href="http://www.enchantedlearning.com/subjects/mammals/smilodon/"><em>Smilodon</em></a> sabre-toothed cat, and other Ice Age cats.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87381/original/image-20150704-20453-1ay1nxr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The skull of the Asian water-deer Hydropotes inermis.</span>
<span class="attribution"><span class="source">Provided.</span></span>
</figcaption>
</figure>
<p>But carnivores do not need to chew their food, so that the Brazilian anomodont had several occluding teeth proved that it was a dedicated herbivore after all.</p>
<p>But the surprises did not end there. <em>Tiarajudens eccentricus</em>, the Brazilian species, show teeth that are commonly located at the margin of the mouth, positioned on a bone of the palate. The novelty is that no other therapsid was known to possess teeth in this bone. In fact no other therapsids are known to have complex, molar-like teeth (molariforms) in the roof of their mouths.</p>
<p>After additional cleaning of the bones of the fossil found in South Africa, called <a href="http://rspb.royalsocietypublishing.org/content/266/1417/331.short"><em>Anomocephalus africanus</em></a>, it was found it also had molariforms in the palate, identical to those of <em>Tiarajudens</em>. The South African fossil has a complete mandible and its teeth are in contact with the palate, confirming the occlusion between upper and lower teeth. The only apparent difference between the two fossils is the absence of blade-like canines in the African species.</p>
<p>The skull of these cousins are nearly the same size – between 210 and 220 mm. They show a domed profile with a very short snout, large orbits, and temporal opening for chewing muscles about the same size or slightly larger than the eye socket.</p>
<p>The long canine in the Brazilian species is represented in a few living deer such as the Asian water-deer, musk-deer, and muntjacs. In all these cases the enlarged canines are used in male-male visual displays during fighting. The long canine in <em>Tiarajudens eccentricus</em> is being interpreted as an indication of its use in a similar way, representing the oldest evidence of use of canine in a herbivore for male-male fight.</p><img src="https://counter.theconversation.com/content/43926/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fernando Abdala receives funding from the National Research Foundation of South Africa.</span></em></p><p class="fine-print"><em><span>Juan Carlos Cisneros receives funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil.</span></em></p>
New evidence shows marked similarities between two fossils – one from Brazil, the other South Africa. This confirms compelling geological findings that continents were once one giant land mass.
Fernando Abdala, Reader, Evolutionary Studies Institute, University of the Witwatersrand
Juan Carlos Cisneros, Lecturer in Palaeontology, Universidade Federal do Piauí (UFPI)
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/21857
2014-01-08T18:22:31Z
2014-01-08T18:22:31Z
We can all learn from Antarctica (when not stuck in the ice)
<figure><img src="https://images.theconversation.com/files/38678/original/bg4bq74c-1389186087.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The very opposite of two weeks in Benidorm.</span> <span class="attribution"><span class="source">Liam Quinn</span></span></figcaption></figure><p>The drama and somewhat unintentional humour of first one and eventually three ships getting caught in heavy sea ice in the Southern Ocean has been closely followed since before Christmas. The <a href="http://america.aljazeera.com/multimedia/photo-gallery/2013/12/photos-from-aboardthemvakademikshokalskiystrandedinantarcticice.html">images</a> of the ship <a href="http://www.polarcruises.com/arctic/ships/shokalskiy">Akademik Shokalskiy</a> held captive in the thick Antarctic icepack caught the attention of people around the world, if not always for the right reasons. </p>
<p>Photos of the Schokalskiy bear little resemblance to <a href="http://www.kodak.com/US/en/corp/features/endurance/">Frank Hurley’s images</a> of the Endurance – the wooden ship of Shackleton’s famous expedition of 1914-17 – that was trapped and shattered in similar pack ice. Yet they raise the same question: why would anyone willingly travel to this barren, cold and dangerous landscape?</p>
<p>For the Schokalskiy voyagers, it was an opportunity to follow the route of another historical expedition, the Australasian Antarctic Expedition led by <a href="http://www.spiritofmawson.com/">Douglas Mawson</a>. Both expeditions are examples of human courage and persistence in the face of incredible risks. Shackleton and crew travelled over 800 nautical miles of open water in a small lifeboat and then hiked another 50km over difficult terrain. Mawson completed an incredible 150km solo trek across wind-blasted <a href="http://icestories.exploratorium.edu/dispatches/antarctic-projects/wilkes-land-expedition/">Wilkes Land</a>. But these expeditions are exceptional; most scientific and tourism-based Antarctic trips are incident free.</p>
<p>In December 2012 I was fortunate enough to participate in the Geological Society of America’s <a href="http://www.geosociety.org/125/antarctica.htm">125th Anniversary Expedition</a> to Antarctica, lead by <a href="http://www.cheesemans.com/">Cheesman’s Safaris</a>. This was not a scientific expedition per se but nor was it just a cruise – more a destination field trip with an emphasis on both local and regional geology.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38676/original/37ymvnpy-1389185683.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">Ice cliffs in the Gerlache Straight, Antarctica.</span>
<span class="attribution"><span class="source">Rachel Milford</span></span>
</figcaption>
</figure>
<p>We sailed aboard the <a href="http://www.oneoceanexpeditions.com/akademik_ioffe/index.php">Akademic Ioffee</a>, the slightly younger sister ship to the Schokalskiy. We departed on December 29 from Port Stanley in the Falkland Islands, and followed sections of Shackleton’s route in a fashion similar to the Schokalskiy retracing Mawson’s path. Many Russian oceanographic vessels built during the Cold War were converted into tourist friendly ships with dorm-style cabins, cinemas, lecture rooms, libraries, dining halls and – in our case – a hot tub and sauna on the upper deck. These amenities meant we were rarely hungry, cold or uncomfortable, other than from sea sickness.</p>
<p>Luckily both our crossings of the <a href="http://www.theweekenderblog.com/2011/02/the-drake-passage-its-not-so-bad-until-it-is/">Drake Passage</a>, the notoriously rough stretch of sea between Cape Horn and the South Shetland Islands, was relatively placid. But to leave the Falklands behind us and crossing the Drake is to officially leave civilisation and enter a foreign environment – even for those of us from northern latitudes accustomed to snow and cold.</p>
<p>It wasn’t the cold that made it feel so foreign. The southern hemisphere’s summer provided comfortable walking temperatures ranging from -2°C to 6°C. Rather, it was the variability in light, the clarity of the atmosphere, and the sight of creatures seen only in the pages of National Geographic.</p>
<p>Our first landing at Peggotty Bluff on <a href="http://www.sgisland.gs/index.php/(h)South_Georgia_webcam">South Georgia Island</a>, where Shackleton also first landed, provided an abrupt introduction to what would greet us for the duration of the trip. As we stepped out of our boats, walking awkwardly wrapped in lifevests, GoreTex, and knee-high rubber boots, we found ourselves faced with territorial fur seals, huge but languid elephant seals bellowing their welcome, and <a href="http://www.bbc.co.uk/nature/life/Gentoo_Penguin">gentoo</a> and <a href="http://www.antarctica.ac.uk/about_antarctica/wildlife/birds/penguins/king.php">king penguins</a> waddling across the shingle. Behind these amazing creatures were white snowfields, sheer black cliffs, and the diffuse blue and green hues of glacial ice.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38680/original/w55kfd79-1389186607.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">“Now reach your flippers up, then down to the ground, and exhale.”</span>
<span class="attribution"><span class="source">Christopher.Michel</span></span>
</figcaption>
</figure>
<p>Moving past South Georgia and further south towards the South Shetland Islands and the Antarctic peninsula, the icebergs we encountered grew in number and size. At first appearing as small growlers showing signs of recent melting and erosion, those we passed grew steadily larger, becoming blocky, table-top icebergs that looked as if they’d recently calved from an ice shelf – although we knew that wasn’t the case. With increasing icebergs came increasing snow cover, which meant fewer opportunities to examine exposed bedrock and penguins. It was interesting to see how penguin diversity decreased as we approached the peninsula, and that the penguin chicks grew smaller and smaller, until we found on Cuverville Island Gentoo penguins still sat on eggs.</p>
<p>Geologically, the field trip focused on the interplay of tectonic plates in the region, as the rocks in this seemingly frozen landscape record an incredibly dynamic history. Dating from the ancient break of <a href="http://www.britannica.com/EBchecked/topic/238402/Gondwana">Gondwanaland</a>, we found exposures of <a href="http://www.pmel.noaa.gov/eoi/nemo/explorer/concepts/pillows.html">pillow lava</a> that represented ancient oceanic crust exposed on South Georgia, volcanic creations like Deception Island, and Jurassic fossils exposed on the Antarctic peninsula. We were kept busy reading the story of geologic time recorded in the rocks.</p>
<p>Passing through the Gerlach Strait and Neumayer Channel, where sheer ice cliffs and soupy pack ice crowded around the ship, I pondered the fate of the MS Explorer – the cruise ship <a href="http://news.bbc.co.uk/1/hi/world/americas/7108835.stm">that sank in 2007</a> after hitting an iceberg in the Bransfield Strait. I can’t speak for the scientists aboard the Schokalskiy, but I still grapple with the tension between the financial cost and carbon footprint of the journey, and the fact that one year on I am still processing what I saw and experienced. The experiences on this trip weren’t limited to the animals or the rocks; I continue to be surprised by how much I learned about the rich history of whaling, political complexity of the <a href="http://www.antarctica.ac.uk/about_antarctica/geopolitical/treaty/">Antarctic Treaty</a> and how tourism crops up up in unexpected ways.</p>
<p>The opportunity to explore an extreme and foreboding, but fascinating environment such as Antarctica with minimal risk is why many people choose it as a destination, and why so many go back.</p><img src="https://counter.theconversation.com/content/21857/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John van Hoesen 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 drama and somewhat unintentional humour of first one and eventually three ships getting caught in heavy sea ice in the Southern Ocean has been closely followed since before Christmas. The images of…
John van Hoesen, Associate Professor of Geology & Environmental Studies, Green Mountain College
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/7658
2012-06-19T20:14:57Z
2012-06-19T20:14:57Z
Australia: moving on up from down under
<figure><img src="https://images.theconversation.com/files/11751/original/69gyv5xw-1339657988.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's time to let go of our old identity.</span> <span class="attribution"><span class="source">Matthew McVickar</span></span></figcaption></figure><p><strong>WHAT IS AUSTRALIA FOR? Australia is no longer small, remote or isolated. It’s time to ask What Is Australia For?, and to acknowledge the wealth of resources we have beyond mining. Currently The Conversation, in conjunction with <a href="http://griffithreview.com/provocations">Griffith REVIEW</a>, is publishing a series of provocations. Our authors are asking the big questions to encourage a robust national discussion about a new Australian identity that reflects our national, regional and global roles.</strong></p>
<p>Australia is on the move. Australia, this thinly populated bastion of the Atlantic-centered, English-speaking world, is drifting towards ever greater union with Asia. If you think this is yet another prognostication about the flow of socio-economic power from the Atlantic Ocean, and the resurgence of a world dominated by Indian and Pacific states, the truth is more literal. Our drift toward Asia is underpinned by something fundamental, a bedrock fact. </p>
<p>With each passing year, our continent drifts 70mm to the northeast towards the equator. This inexorable motion, which is happening at a velocity somewhere between the rate at which hair and fingernails grow, is driving us towards <a href="http://sideshow.jpl.nasa.gov/mbh/series.html">inevitable collision and amalgamation</a> with the Asian continent. It seems as though the geological processes underfoot are conspiring with world events to bring us even closer to the centre.</p>
<p>So, if we could afford to wait a few tens of millions of years, we would see our future in a new continental array that we can call <a href="http://www.scotese.com/futanima.htm">“Austrasia”</a>. </p>
<p>If we want to know how we got here, we can think of the present moment as a snapshot of a long-running geological motion picture lasting some 4.5 billion years. If our movie lasts for two hours, then each “geominute” of our film will encompass 37.5m years, and each “geosecond” represents a little more than 300,000 years. </p>
<p>To put this into perspective, had you been been distracted from the last five geoseconds of the film, you would have missed the entire emergence of <em>Homo sapiens</em> from Africa. Getting up for two geominutes to get something from the refrigerator would mean you missed the impact of a 10km asteroid into the Yucatan peninsula (in present-day Mexico), wiping out the dinosaurs and ushering in the Age of Mammals.</p>
<p>We should back up a few geominutes to get some perspective on where Australia has been, so that we see the changing position of our continent in both absolute terms, but also relative to other continents. From the standpoint of European colonists (arriving a ten-thousandth of a geosecond ago), the cultural and economic remoteness of Australia was imposed by geography (though physical geography is anthropomorphised geology with climate added in). This geological isolation of Australia was set into motion nearly 200m years ago. Before this time, Australia was more cosmopolitan, a citizen of the Gondwana supercontinent, that massive landbody occupying most of the Southern Hemisphere. The other member states – Africa, South America, India, Antarctica – were arranged in a fixed geometry that moved in unison, slowly drifting together for more than 300m years from the time of their first assembly.</p>
<p>During the Gondwana portion of Australia’s history, our flora and fauna were not improbable creatures surviving in nearly impossible conditions, the peculiar denizens of a dusty reliquary. At that time, Australia’s plants and animals were part of a broad family spread across the greater part of Gondwana. A classic example of a Gondwanan-type species are the marsupials, which, until recently, were the dominant mammals in South America. “Recently” in this case refers to the Pliocene epoch, 3-5m years ago (or 18 geoseconds ago in our film). That was when the closing of the isthmus of Panama allowed the invasion of North American placental mammals, decimating the ranks of South American endemic species in a story that is familiar to anyone in Australia. (Care to wager on the outcome of a race for survival between the bilby and the rabbit?) </p>
<p>Since the extinction of the native South American fauna happened before humans had colonised the Americas, and therefore in a guilt-free geological past, this tragedy is referred to in rather anodyne terms as the “The Great American Biotic Interchange”. Great for the migrants from the North, not so great for the South American species. With the exception of possums and armadillos, they were largely unable to penetrate the North American ecosystem from their geographic base in South America.</p>
<p>In a strange historical coincidence, the same man who laid the observational foundation for the biological invasion of South America, Alfred Russell Wallace, also defined the boundaries of Australian biogeography. A contemporary and colleague of Charles Darwin, Wallace spent many years in the Amazon basin, and then several more in the “East Indies”, more familiar to us as the region containing the modern countries of Indonesia and Malaysia. His observations of the distinct fauna populating different islands of the archipelago allowed him to draw a geographic boundary separating species of Asian affinities from those that derived from the Australian continent. This boundary is now known as the Wallace line, in his honour (scant honour indeed for the man whose findings finally goaded Darwin out of a 13-year reverie of barnacle studies into publishing On the Origin of Species). </p>
<p>Wallace was no stranger to the obscure; during his field studies in the East Indies, he collected about 80,000 specimens of beetle, but that was mostly for sale to collectors in order to finance his habit of making bad investments in British railroad concerns. Wallace is now best known as the father of biogeography, the study of changing patterns of species in different regions through time.</p>
<p>Digression aside, biogeography alone cannot answer our question about Australia’s past. After all, living organisms move around much faster than the continents. Our question about where Australia has been is really a question of paleogeography, the reconstruction of ancient continental configurations, a cartography of past worlds. If we want to know about the migration of Australia, we have to study the rocky bones of the continent itself. </p>
<p>One of the most important tools for our pursuit of paleogeography is paleomagnetism, the study of ancient magnetic directions preserved in rocks. Since the geometry of the Earth’s magnetic field varies with latitude, the fossilised record of past magnetic fields allows us to pinpoint the position and orientation of the continent in the past. This is possible because most rocks contain trace amounts of the minerals magnetite and hematite. Just like the needle in a magnetic compass points north, these minerals will become magnetically oriented by Earth’s magnetic field when they form, say, during the solidification and cooling of a hot, molten lava.</p>
<p>Using paleomagnetism as our compass, we can track the motion of Australia back continuously for at least the past 550m years (or roughly 15 minutes in our geofilm), but with increasing difficulty for time periods much older than that. These last 15 minutes of the geofilm begin with the period just after Gondwana had formed, with Australia at the easternmost portion of the great landmass. Given the near hemispheric girth of Gondwana, parts of the supercontinent could be located at very high, polar latitudes, while other regions could be located in balmy, tropical locations. So, it is helpful to concentrate only on Australia, which at this point 550m years ago, sat astride the equator, but rotated almost 90˚ clockwise from its present orientation. Slowly, the entire continent begins to rotate in a counterclockwise motion. </p>
<p>At one point, during the middle Devonian (370m years ago, or 10 minutes ago in our geofilm), the position of Australia was coincidentally almost identical to the modern position and orientation. So, the Canning Basin of northern Western Australia was the location for Devonian version of the Great Barrier Reef. Over the next 100m years, the position of Australia moved steadily south, towards more temperate zones, and finally to the edge of the Antarctic Circle by roughly 270m years ago (seven minutes ago, in our geofilm). Not surprisingly, the record of paleoclimate from this period of time alternates between dry glacial periods and moist, cool-temperate forests.</p>
<p>Finally, about 150m years ago, Australia begins to slowly move back towards the equator. Now something is different, for cracks are beginning to develop in the Gondwanan shield. These cracks were marked by large outpouring of basaltic lavas, such as the dolerite sills and dykes that form Tasmania’s Cradle Mountain. With time, these cracks would widen would widen into rift valleys, and rift valleys would become ocean basins. The splintering of Gondwana would give birth to the Indian, South Atlantic, and Southern Oceans - you can watch an animation of the splintering <a href="http://www.scotese.com/satlanim.htm">here</a>. For Australia, our last break-up would be with Antarctica. The cracks that had begun to develop in the late Cretaceous were already developing into a narrow ocean by the late Paleocene, roughly 55m years ago, or a little more than a minute of our geofilm.</p>
<p>It is in the last minute of our geofilm that the modern contours of Australia emerge, the geographic isolation imposed by the separate path we are drifting along.</p>
<p>Australia is now heading steadily northwest, and every year brings us closer to becoming part of Asia. Already we can see the effects of this in Timor. Timor, which is the northernmost edge of the Australian continental plate, is crumpling from the tectonic strain brought about by the slow-motion collision with Indonesia. Antipodal only to the Atlantic, Australia will once again be part of a new supercontinent. Long live Austrasia!</p>
<p><em>Read more provocations at <a href="https://theconversation.com/topics/what-is-australia-for">The Conversation</a> and at <a href="http://griffithreview.com/provocations">Griffith REVIEW</a>.</em></p><img src="https://counter.theconversation.com/content/7658/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Tohver receives funding from the Australian Research Council and Chevron Australia.</span></em></p>
WHAT IS AUSTRALIA FOR? Australia is no longer small, remote or isolated. It’s time to ask What Is Australia For?, and to acknowledge the wealth of resources we have beyond mining. Currently The Conversation…
Eric Tohver, Associate Professor of Geology, The University of Western Australia
Licensed as Creative Commons – attribution, no derivatives.