tag:theconversation.com,2011:/us/topics/mammal-extinction-50957/articlesmammal extinction – The Conversation2021-02-04T04:01:13Ztag:theconversation.com,2011:article/1530942021-02-04T04:01:13Z2021-02-04T04:01:13ZThis unique ancient megabeast had perpetually ‘bent’ elbows<p>Imagine going through life with your arms permanently bent and locked at the elbows. Awkward, right? </p>
<p>Until recently we thought the mega-marsupial <a href="https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/600-million-years/timeline/quaternary/palorchestes/index.html"><em>Palorchestes azael</em></a> lived exactly like this. This rare, distant relative of the wombat became extinct (along with much of Australia’s megafauna) about 40,000 years ago.</p>
<p>But our research, published <a href="https://onlinelibrary.wiley.com/share/author/8GU9UT45FRETQ33CMXHV?target=10.1111/joa.13389">today in the Journal of Anatomy</a>, shows <em>Palorchestes</em> could in fact move its elbows — but only a very tiny amount compared to other mammals. </p>
<p>Thus, we think this enigmatic creature would have had a highly unusual gait, which may provide a clue to why it went extinct. </p>
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Read more:
<a href="https://theconversation.com/meet-the-giant-wombat-relative-that-scratched-out-a-living-in-australia-25-million-years-ago-141296">Meet the giant wombat relative that scratched out a living in Australia 25 million years ago</a>
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<h2>A strange setup</h2>
<p>The humble elbow has been around since the ancestors of all <a href="https://youtu.be/LcQdWIInnk8">four-limbed animals first hauled</a> themselves out of the water and onto land. </p>
<p>For most mammals, the elbow is a hinge-like joint that connects the humerus (which runs from shoulder to elbow) with the ulna and radius (which run from elbow to wrist). </p>
<p>The elbow allows the bending and straightening of the arm and is essential for four-legged walking. In the wild it’s also useful for tasks such as feeding, fighting, climbing and grooming. </p>
<p>But <em>Palorchestes</em> seemingly gave much of that up. Unlike other large mammals alive or extinct, it kept its arms in a perpetual “push-up” position.</p>
<p>So what would moving around have looked like for <em>Palorchestes</em>? And why might it have evolved such a narrow range of elbow motion in the first place? </p>
<h2>Peculiar <em>Palorchestes</em></h2>
<p><em>Palorchestes</em> was an unusual-looking marsupial. With a slender jaw indicating a long tongue and tiny nasal bones retracted high up in a narrow skull, some palaeontologists have suggested it had a tapir-like trunk (<a href="https://doi.org/10.1111/joa.13389">although others think this is unlikely</a>). </p>
<p>Fossils of <em>Palorchestes’s</em> robust bones show evidence of heavily muscled forelimbs with huge, sharp claws suited for clinging and tearing. And we recently found it may have grown to <a href="https://doi.org/10.1371/journal.pone.0221824">weigh more than a tonne</a>. </p>
<figure class="align-center ">
<img alt="Large fossil claw on a human palm." src="https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=520&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=520&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=520&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=653&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=653&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378192/original/file-20210112-23-vaj5tw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=653&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The massive claw bone of <em>Palorchestes azael</em> is equivalent to the bone we have in our fingertip. When <em>Palorchestes</em> was alive, this claw bone would have been covered by a keratin sheath that extended its length up to 50%.</span>
<span class="attribution"><span class="source">Hazel Richards</span></span>
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<p>Still, for us the most interesting aspect of <em>Palorchestes</em> is its flattened elbow joint surfaces, which seem to indicate its elbows stayed bent at around a 100° angle.</p>
<p>We scanned the fossilised arm bones of <em>Palorchestes</em> and created computer simulations to model the full range of movements possible at its arm joint. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photographs of pangolin, sloth bear, anteater, wombat, koala, aardvark." src="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=655&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=655&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=655&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=823&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=823&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378490/original/file-20210113-23-lccrm5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=823&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Palorchestes</em> had drastically less elbow mobility than the living mammals we compared it to. Clockwise from the top left: pangolin, sloth bear, anteater, wombat, koala and aardvark.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
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<p>Our results indicate <em>Palorchestes</em> could move its elbows, but only in an off-axis motion that was tiny compared to other clawed mammals with chunky limbs such as wombats, pangolins, aardvarks and bears. Even its <a href="https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/600-million-years/timeline/quaternary/zygomaturus/index.html">closest extinct megafaunal relatives</a> had vastly more elbow function. </p>
<p>This suggests none of these creatures are good templates for understanding how <em>Palorchestes</em> moved.</p>
<p>By adding sliding movement as well as rotations, we used our 3D simulations to calculate the “average” motion in <em>Palorchestes</em>, from fully flexed to fully extended elbow poses. We found the axis of this small movement was skewed, like a “wonky” hinge. </p>
<p>The interactive below shows the maximum elbow motion that would have been theoretically possible for <em>Palorchestes azael</em>.</p>
<div class="sketchfab-embed-wrapper">
<iframe title="A 3D model" width="100%" height="480" src="https://sketchfab.com/models/fbf63a5f7b9b4011be63990cf4b2a242/embed?autostart=0&ui_controls=1&ui_infos=1&ui_inspector=1&ui_stop=1&ui_watermark=1&ui_watermark_link=1" frameborder="0" allow="autoplay; fullscreen; vr" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>
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<a href="https://sketchfab.com/3d-models/maximum-elbow-motion-in-palorchestes-azael-fbf63a5f7b9b4011be63990cf4b2a242?utm_medium=embed&utm_source=website&utm_campaign=share-popup" target="_blank"></a>
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<p>This skew means <em>Palorchestes</em> probably held its arms sprawled out from its body, allowing what little elbow mobility was possible to contribute to each stride while walking.</p>
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<a href="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two possible forelimb postures for Palorchestes" src="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378217/original/file-20210112-13-1eoh823.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">We modelled the whole range of motion possible at Palorchestes’s elbow to calculate its ‘average’ movement. If placed in a ‘normal’ mammal forelimb posture, <em>Palorchestes’s</em> hands would splay out to the sides as the elbows moved (left image). Instead, having forelimbs in a sprawled posture would have let its minute elbow movements contribute to each stride (right image)</span>
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<h2>Arms akimbo make for awkward walking</h2>
<p>Our findings suggest <em>Palorchestes</em> would have trundled along on crouched forelimbs, with its elbows sprawled out to the sides — a highly inefficient gait compared with <a href="https://doi.org/10.1126/science.2740914">the pillar-like limbs</a> and tucked-in elbows of its relatives and large mammals alive today.</p>
<p>We think this posture was a compromise which let it use its strong arms and giant claws to access food in a specialised way, which was probably unique even back then.</p>
<p>While exact details remain a mystery, it could be that <em>Palorchestes</em> clung to tree trunks and hauled itself up onto its back legs to reach higher foliage with its long tongue. </p>
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<a href="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Painting of Palorchestes rearing up against a tree" src="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=932&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=932&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=932&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1171&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1171&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378210/original/file-20210112-13-bcyneg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1171&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This reconstruction of <em>Palorchestes azael</em> is from the 1980s. Although we now know the forelimb position shown here was highly unlikely, Palorchestes may have still used its strong arms and bent elbows to haul itself up against trees like this for better access to foliage.</span>
<span class="attribution"><span class="source">Peter Schouten</span></span>
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<p>Or it might have used its huge, bulky body to push over tree ferns to access the young nutritious fronds higher up. </p>
<p>Whatever it did, <em>Palorchestes</em> was evidently pretty successful. While its fossils are rare, they’re widely distributed right across eastern Australia. </p>
<h2>The specialisation trap</h2>
<p>The fossils of <em>Palorchestes</em> tell us it was a specialist, highly adapted to a forest landscape. </p>
<p>Large animals have large appetites to match, but <em>Palorchestes’s</em> inefficient walk probably limited its ability to roam widely in search of food. </p>
<p>This would be no problem in times of plenty. But when shifts in Australia’s climate caused sweeping environmental changes across <a href="https://doi.org/10.1038/s41467-020-15785-w">the eastern half of the continent</a>, large specialised megafauna such as <em>Palorchestes</em> were especially vulnerable. </p>
<p>Even small changes in the vegetation mix would have made it difficult to find enough food.</p>
<figure class="align-center ">
<img alt="Lush Tasmanian forest with a Dicksonia tree fern and mossy logs" src="https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378194/original/file-20210112-17-10o3j7z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"><em>Palorchestes</em> probably lived in forests such as this one in Tasmania and may have used its specialised forelimbs to tear apart ferns and logs.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
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<p>So an adaptation that can be a recipe for success in one environment can lead to a <a href="https://doi.org/10.1093/icb/42.2.265">species’ demise in a changing world</a>. </p>
<p>And while there’s nothing like <em>Palorchestes</em> alive today, many unique species now face the same fate due to drastic changes in their habitats. </p>
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Read more:
<a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">Did people or climate kill off the megafauna? Actually, it was both</a>
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<img src="https://counter.theconversation.com/content/153094/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hazel L Richards is supported by an Australian Government Research Training Program scholarship and a Monash-Museums Victoria PhD top-up scholarship. </span></em></p><p class="fine-print"><em><span>Alistair Evans receives funding from Australian Research Council, and is an Honorary Research Affiliate at Museums Victoria.</span></em></p><p class="fine-print"><em><span>Justin W. Adams receives funding from the Australian Research Council and is a Research Associate with the Palaeo-Research Institute at the University of Johannesburg, South Africa.</span></em></p><p class="fine-print"><em><span>Peter Bishop receives funding from Harvard University and is an Honorary Researcher in the Geosciences Program of the Queensland Museum.</span></em></p><p class="fine-print"><em><span>David Hocking does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A new study shows Palorchestes had unique elbows unlike any other mammal, which may have contributed to its extinction.Hazel L. Richards, PhD candidate, Monash UniversityAlistair Evans, Associate Professor, Monash UniversityDavid Hocking, Adjunct Research Associate, Monash UniversityJustin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash UniversityPeter Bishop, Postdoctoral research fellow, Harvard Kennedy SchoolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1476562020-10-07T19:10:21Z2020-10-07T19:10:21ZIt was growing rainforests, not humans, that killed off Southeast Asia’s giant hyenas and other megafauna<figure><img src="https://images.theconversation.com/files/362096/original/file-20201007-14-1ciu27.jpeg?ixlib=rb-1.1.0&rect=56%2C56%2C4159%2C3148&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Peter Schouten</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Thinking of Southeast Asia today may conjure up images of dense tropical rainforests teeming with iconic jungle animals such as orangutans, tigers and monkeys.</p>
<p>Perhaps less well known, but just as important to these ecosystems, are a host of other large-bodied creatures: the goat-like <a href="https://en.wikipedia.org/wiki/Serow">serows</a> and <a href="https://en.wikipedia.org/wiki/Goral">gorals</a>, <a href="https://www.wwf.org.uk/learn/wildlife/asian-rhinos">three species of Asian rhino</a> and the only species of <a href="https://en.wikipedia.org/wiki/Malayan_tapir">tapir</a> still living in the “Old World”.</p>
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<a href="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tapir sitting in a green forest." src="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The endangered Malayan tapir is the largest of four widely-recognized tapir species and the only one native to Asia.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>Together, these creatures comprise Southeast Asia’s megafauna, second only to Africa’s in diversity. These two continental ecosystems are the last vestiges of a world largely lost – one where giants roamed the Earth. But what caused so many megafauna species to go extinct?</p>
<p>Several theories have suggested either humans, climate change, or both drove Southeast Asia’s megafauna to extinction. However, our newest research published today in <a href="https://www.nature.com/articles/s41586-020-2810-y">Nature</a> indicates it was actually the rise and fall of savannah environments that drove this extinction event.</p>
<h2>Southeast Asia’s megafauna extinctions</h2>
<p>Southeast Asia has lost many large mammal species over the Quaternary period, the past 2.6 million years. They included the world’s largest ever ape, <em><a href="https://en.wikipedia.org/wiki/Gigantopithecus">Gigantopithecus</a></em>, elephant-like creatures known as <a href="https://en.wikipedia.org/wiki/Stegodon">stegodons</a> and large water buffaloes.</p>
<p>These extinctions also include one of our closest relatives, <em>Homo erectus</em>, and two island offshoots of the human family tree – <em>Homo floresiensis</em> (the “Hobbit”) and <em>Homo luzonensis</em>. One final human species is also recorded in the genes of Southeast Asians today: the Denisovans, who were once <a href="https://cosmosmagazine.com/palaeontology/southeast-asia-was-crowded-long-before-we-turned-up/">likely widespread throughout the region</a>.</p>
<p>According to <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">previous research</a>, the lead antagonist in the megafauna extinction story is humans. Some have suggested the arrival of people to new lands over the past 60,000 years or more – who then overhunted and altered this new habitat – is what led to the loss of giant mammals. </p>
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Read more:
<a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">New analysis finds no evidence that climate wiped out Australia's megafauna</a>
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<p>Others researchers have contended <a href="https://theconversation.com/humans-coexisted-with-three-tonne-marsupials-and-lizards-as-long-as-cars-in-ancient-australia-138534">changes in climate</a> resulted in the extinction of the megafauna. While others suggest a <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">combination</a> of both human and climate influences. </p>
<h2>Toothy insights into past environments</h2>
<p>For our research, we examined environmental changes in Southeast Asia over the <a href="https://www.nationalgeographic.com/science/prehistoric-world/quaternary/">past 2.6 million years</a>, to determine how they may have impacted extinctions. </p>
<p>We analysed the <a href="https://www.futurelearn.com/courses/archaeology/0/steps/15267">stable isotopes</a> of the teeth of mammals found in the region today, as well as those from available published fossil records.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-giant-wombat-relative-that-scratched-out-a-living-in-australia-25-million-years-ago-141296">Meet the giant wombat relative that scratched out a living in Australia 25 million years ago</a>
</strong>
</em>
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<p>Stable isotopes are the non-radioactive forms of many elements. Stable isotopes of carbon and oxygen preserved in mammal teeth record important information on what kinds of plants those animals ate, and how wet their environments were, respectively. </p>
<p>Stable carbon isotopes are particularly helpful in recording whether animals predominantly ate leaves and fruits in shaded forests, or grasses in more open settings. This insight lets us identify shifts in environments over time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ancient tooth fossils." src="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These fossil teeth from extinct Southeast Asian elephants are one example of the various teeth available in the fossil record.</span>
<span class="attribution"><span class="source">Julien Louys</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The fluctuating presence of forests</h2>
<p>During the first 1.5 million years or so of the Pleistocene (the geological epoch that lasted from about 2,580,000 to 11,700 years ago), the northern parts of Southeast Asia were largely forest, while the southern parts were woodlands or grasslands. </p>
<p>Later, from about one million years ago, forests retreated everywhere in the region and grasslands dominated. Coincident with these changes, large forest-adapted animals including <em>Gigantopithecus</em> and a giant panda relative disappeared from Southeast Asia’s northern parts.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Model recreation of Gigantopithecus blacki." src="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Gigantopithecus blacki</em> was a large extinct ape that lived during the Pleistocene in what is now Southern China. It’s believed to have gone extinct about 300,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/22077805@N07/5484933159/in/photostream/">Greg Williams/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Later still, around 400,000 years ago, the Southeast Asian Sunda Shelf began to submerge and climate cycles changed. Because of this, forest conditions returned.</p>
<p>At the same time, grassland-adapted creatures that had filled the region, including giant hyenas, <a href="http://www.eartharchives.org/articles/stegodon-the-elephant-with-sideways-trunk/">stegodons</a>, <a href="https://www.britannica.com/animal/bovid">bovids</a> and <em>Homo erectus</em> began to disappear – and largely went extinct by the end of the Pleistocene. The remainder were driven into the rainforests. </p>
<p>By the last few tens of thousands of years, we see the first evidence of <a href="https://en.wikipedia.org/wiki/Stratification_(vegetation)">stratified</a>, closed-canopy rainforests in Southeast Asia. These have dominated the region for the past 20,000 years or so.</p>
<p>Rainforest-adapted species should have been advantaged by the return of the rainforests, but one interloper changed that. <em>Homo sapiens</em> appears to be the only species in our family tree that was able to successfully adapt to and exploit rainforest environments. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/old-teeth-from-a-rediscovered-cave-show-humans-were-in-indonesia-more-than-63-000-years-ago-82075">Old teeth from a rediscovered cave show humans were in Indonesia more than 63,000 years ago</a>
</strong>
</em>
</p>
<hr>
<p>And although humans lived in Southeast Asian rainforests as early as 73,000 years ago, it was probably only <a href="https://advances.sciencemag.org/content/4/6/e1701422">in the last 10,000 years</a> that <em>Homo sapiens</em> began to fundamentally alter these habitats and exploit the mammals within. </p>
<h2>A vanishing world</h2>
<p>Southeast Asia continues to preserve some of the most critically endangered megafauna on the planet. </p>
<p>Megafauna grassland specialists were the greatest loss as a result of disappearing savannahs 400,000 years ago. Today, rainforest megafauna are also at great risk of extinction. </p>
<p>Luckily for us, our own species’ fortunes changed for the better with the emergence of typical Southeast Asian rainforests. But we’re now the very thing threatening to <a href="https://theconversation.com/guns-snares-and-bulldozers-new-map-reveals-hotspots-for-harm-to-wildlife-113361">destroy them forever</a>.</p><img src="https://counter.theconversation.com/content/147656/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Patrick Roberts receives funding from the Max Planck Society and the European Research Council.</span></em></p>Several theories have suggested either humans, climate change or both drove megafauna extinctions in Southeast Asia. Our newest work suggests otherwise.Julien Louys, ARC Future Fellow, Griffith UniversityPatrick Roberts, Research Group Leader, Max Planck Institute of GeoanthropologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/932032018-03-12T19:06:12Z2018-03-12T19:06:12ZYes, kangaroos are endangered – but not the species you think<p>Do you know what kind of animal the mala, nabarlek, or boodie is? What about the monjon, northern bettong, or Gilbert’s potoroo? </p>
<p>If you answered that they are different species of kangaroo – the collective term for more than 50 species of Australian hopping marsupials – you’d be right. But you’d be in the minority. </p>
<p>Include nearby New Guinea, and the number of kangaroo species jumps to <a href="https://cloud.une.edu.au/index.php/s/QxtzrSSG2FcwKQC">more than 70</a>. Kangaroos are so diverse that they have been dubbed <a href="https://books.google.com.au/books?id=X1aDI8F9ULYC&printsec=frontcover#v=onepage&q&f=false">Australia’s most successful evolutionary product</a>.</p>
<p>But sadly, not everyone is aware of this great diversity, so most kangaroo species remain obscure and unknown.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bans-on-kangaroo-products-are-a-case-of-emotion-trumping-science-47924">Bans on kangaroo products are a case of emotion trumping science</a>
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</em>
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<p>This is brought into sharp relief by a new movie that premieres nationally this week called <a href="http://kangaroothemovie.com">Kangaroo: A Love-Hate Story</a>. The filmmakers set out to expose the kangaroo industry, painting a picture of gruesome animal cruelty, an industry cloaked in secrecy, and the wholesale slaughter of an Australian icon.</p>
<p>The film, which includes brutal footage, also includes the claim that Australia’s kangaroos may be heading down the path of extinction.</p>
<p>The film has already screened in the United States and Europe to sold-out premieres, opening first in those places because they are important markets for kangaroo products. </p>
<p>But foreign audiences also probably know less about Australia’s major kangaroo species or the complexities of the kangaroo industry, and may perhaps be more easily swayed towards the filmmakers’ point of view.</p>
<p>Many US reviews have been positive about the film, although <a href="https://www.hollywoodreporter.com/review/kangaroo-a-love-hate-story-1074383">one review</a> described it as “frustratingly one-sided”.</p>
<p>Most Australians, whatever their view on the kangaroo industry, would surely agree that if kangaroos are to be harvested, it should be done with minimal suffering. But are Australia’s kangaroos really at risk of extinction?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209853/original/file-20180312-30954-1cr9qdp.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The iconic red kangaroo. Large kangaroos are typically widespread and secure, unlike many of their smaller cousins.</span>
<span class="attribution"><span class="source">Karl Vernes</span></span>
</figcaption>
</figure>
<p>On mainland Australia, <a href="http://www.environment.gov.au/biodiversity/wildlife-trade/natives/wild-harvest">four species are sustainably harvested</a>, largely for their meat or fur: the eastern grey, western grey, common wallaroo, and Australia’s most famous icon (and largest marsupial), the red kangaroo. </p>
<p>The <a href="http://www.environment.gov.au/system/files/pages/d3f58a89-4fdf-43ca-8763-bbfd6048c303/files/kangaroo-statistics-2018.pdf">best scientific survey data</a>, based on millions of square kilometres surveyed by aircraft each year, puts the combined number of these four kangaroo species currently at around 46 million animals.</p>
<p>This is a conservative estimate, because only the rangelands where kangaroos are subject to government-sanctioned harvest are surveyed. There is almost as much kangaroo habitat again that is not surveyed. </p>
<p>Of the estimated population, a quota of roughly 15% is set for the following year, of which <a href="http://www.environment.gov.au/system/files/pages/d3f58a89-4fdf-43ca-8763-bbfd6048c303/files/kangaroo-statistics-2018.pdf">barely a quarter is usually filled</a>. Quotas are set and enforced by state governments, with the aim of sustaining population numbers.</p>
<p>For example, of 47 million animals estimated in 2016, a quota of 7.8 million animals was set for the following year, but only 1.4 million of these animals (3.1% of the estimated population) were harvested.</p>
<p>The wildlife management community is pretty much <a href="https://www.awms.org.au/the-commercial-harvesting-of-macropods">unanimous</a> that the four harvested species are widespread and abundant, and at no risk of extinction.</p>
<h2>Are non-harvested species at risk?</h2>
<p>But what of the other forgotten 95% of kangaroo species? The conservation prognosis for these – especially the smaller ones under about 5.5kg in weight – is far less rosy. </p>
<p>The <a href="http://www.australianwildlife.org/wildlife/nabarlek.aspx">nabarlek</a> – a small <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=87607">endangered</a> rock wallaby from Australia’s northwest – has become so rare that its mainland population in the Kimberley seems to have disappeared. It is now only found on a few islands off the coast. </p>
<p>The <a href="http://www.australianwildlife.org/wildlife/burrowing-bettong.aspx">boodie</a> – a small burrowing species of bettong – was one of Australia’s most widespread mammals at the time of European arrival, but is extinct on the mainland and now found on just a few islands.</p>
<p><a href="https://theconversation.com/australian-endangered-species-gilberts-potoroo-11640">Gilbert’s potoroo</a> holds the title of Australia’s most endangered mammal, clinging precariously to existence in the heathlands around Albany on Western Australia’s south coast. One intense wildfire could wipe out the species in the wild. </p>
<p>Meanwhile, if the alarming increasing impact of cats on our northern Australian wildlife continues, <a href="http://www.publish.csiro.au/WR/justaccepted/WR16103">recent modelling</a> suggests that the <a href="https://en.wikipedia.org/wiki/Northern_bettong">northern bettong</a> – a diminutive kangaroo that weighs barely a kilogram – will disappear.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australian-endangered-species-gilberts-potoroo-11640">Australian endangered species: Gilbert's Potoroo</a>
</strong>
</em>
</p>
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<p>The list goes on: mala, bridled nail-tail wallaby, parma wallaby, woylie, banded hare-wallaby, long-footed potoroo, Proserpine rock-wallaby – all of these and more could slip to extinction right under our noses. </p>
<p>The culprits are the usual suspects: cats, foxes, land-use change – and our collective apathy and ignorance. Australia holds the title for the <a href="http://www.abc.net.au/news/2015-08-19/fact-check-does-australia-have-one-of-the-highest-extinction/6691026">worst record of mammal extinctions in modern times</a>, and kangaroos, unfortunately, contribute many species to that list.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209870/original/file-20180312-30961-orgz41.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Population modelling paints a grim picture for the northern bettong.</span>
<span class="attribution"><span class="source">Karl Vernes</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="https://www.youtube.com/watch?v=8Oaeaqndd7g">theatrical trailer</a> for Kangaroo: A Love-Hate Story’ features a voiceover from a concerned kangaroo activist, who says: </p>
<blockquote>
<p>If Australians really knew what happens out there in the dark, they would be horrified.</p>
</blockquote>
<p>Indeed they might. But it’s not just the treatment of the abundant big four kangaroos that are harvested (yet secure) that should attract attention. </p>
<p>If we also look at the other 95% of kangaroo species that need our urgent attention, we might just be able to do something about their dwindling numbers - and the real kangaroo extinction crisis - before it’s too late.</p><img src="https://counter.theconversation.com/content/93203/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Vernes has received research funding from a range of funding bodies, including the Australian Research Council, the Hermon Slade Foundation, the New South Wales National Parks and Wildlife Service, and the Invasive Animals Cooperative Research Centre. He is not affiliated with the Kangaroo Industries Association of Australia, nor has he ever received funding from them.</span></em></p>A new documentary makes some controversial claims about the health of kangaroo populations. But the real threat is not to Australia’s iconic kangaroos – it’s to dozens of other, obscure species.Karl Vernes, Associate Professor, School of Environmental & Rural Science, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.