tag:theconversation.com,2011:/au/topics/palaeontologists-18505/articlesPalaeontologists – The Conversation2021-06-16T14:18:16Ztag:theconversation.com,2011:article/1618212021-06-16T14:18:16Z2021-06-16T14:18:16ZSouth African dinosaur skeleton scans build up a picture from egg to adult<figure><img src="https://images.theconversation.com/files/407399/original/file-20210621-35174-1rwii45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Massospondylus fossils help researchers develop a full picture of this dinosaur species. </span> <span class="attribution"><span class="source">Dorling Kindersley ltd / Alamy Stock Photo/Not for re-use</span></span></figcaption></figure><p>If you ask children what their favourite dinosaurs are, the answers will undoubtedly include <em>T. rex</em>, <em>Triceratops</em> and maybe <em>Brachiosaurus</em>. Those children answering the question in South Africa may be disappointed to discover that none of these dinosaur fossils are to be found in the country.</p>
<p>But South Africa has its own, equally important dinosaurs; the most common and well known of these is <em>Massospondylus</em>, which was first described by scientists back in 1854. This dinosaur was approximately 4-5m long from head to tail, walked on two legs, had a long neck, a small head and ate plants. It lived in the Early Jurassic time period – 200 million years ago – of <a href="http://wiredspace.wits.ac.za/handle/10539/26829">southern Africa</a>. It was also the ancestor of the colossal creatures so many children can name today: <em>Massospondylus</em> gave rise to giants like <em>Diplodocus</em>.</p>
<p><em>Massospondylus</em> is a crucial dinosaur for palaeontologists. This is partly because <em>Massospondylus</em> is the most common dinosaur fossil found in southern Africa, and also because there are fossils of these animals ranging in age from embryos still in their eggs, to babies, to adolescents to adults. The oldest mature individual that has been studied reached about 25 years. The range of fossils available means that researchers can study their growth. </p>
<p>For the past eight years, I have been using an array of different methods – <a href="https://www.mayoclinic.org/tests-procedures/ct-scan/about/pac-20393675#:%7E:text=A%20computerized%20tomography%20(CT)%20scan,than%20plain%20X%2Drays%20do">computerised tomography</a> (CT) scans, statistics, <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0843">studying the bones under a microscope</a> – to answer questions about <em>Massospondylus</em>’ development.</p>
<p>The more we learn about this species’ growth and development, the better we’re able to understand the diversity of animals and ecology 200 million years ago. </p>
<h2>CT scans</h2>
<p>Part of my work involves understanding how <em>Massospondylus</em> skeletons, especially their skulls, change as they grow up. This is important because if scientists don’t know what a species’ skull looked like at different ages, they might not be able to accurately ascertain what species existed in a particular place and time. </p>
<p>For instance, a palaeontologist might find two dinosaur skeletons, one big and one small, and assume these belonged to two different species. That would increase the diversity of the past ecology that’s being reconstructed. However, if the small skeleton is a baby version of the larger one, this changes the picture. </p>
<p>The best way to look at skulls in detail is to scan them with computerised tomography. CT scans work with X-rays, except that instead of one image, they produce a stack of thousands of images. These can be used to digitally reconstruct the fossil bones in three dimensions and look at features that were inside the bones, invisible to the naked eye. Using these scans, I <a href="https://peerj.com/articles/4224/">reconstructed a series</a> of <em>Massospondylus</em> skulls, from babies to adults, and described the shape changes. This now allows us to <a href="https://peerj.com/articles/7240/">easily identify</a> fossils as being <em>Massospondylus</em>, or not.</p>
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<a href="https://theconversation.com/a-fossil-hidden-in-plain-sight-in-south-africa-turns-out-to-be-a-new-dinosaur-121597">A fossil hidden in plain sight in South Africa turns out to be a new dinosaur</a>
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<p>As a researcher studying how dinosaurs grow, I am interested in the absolute beginning of development: embryos. One of the most famous <em>Massospondylus</em> specimens is a clutch of seven eggs with embryos found in 1976 in South Africa’s Free State province. Using high-powered CT scans, I reconstructed the 1cm long skulls of these tiny creatures and compared them to dinosaurs’ <a href="https://www.smithsonianmag.com/science-nature/dinosaurs-living-descendants-69657706/">closest living relatives</a>: chickens, crocodiles, turtles and lizards. </p>
<p>I found that the bones in the <em>Massospondylus</em> embryo skulls developed in the same order as those in animals today. This allowed me <a href="https://www.nature.com/articles/s41598-020-60292-z#Sec6">to determine</a> that the <em>Massospondylus</em> embryos were only 60% through their incubation period when they were buried. It also means that the skulls of embryos in this group have conserved their developmental sequence for an extraordinary 250 million years of evolution. It’s not yet known how far back this pattern goes in evolution but it could potentially appear in very early tetrapods (four-limbed animals). Tetrapods go through a lot of changes in evolution, so having a constant feature is quite significant and indicative that you don’t mess with a good thing.</p>
<h2>Posture and evolution</h2>
<p>These scans can also be used to digitally fill in empty spaces where soft tissues like brains and inner ears once were. Inner ears are made up of canals and a chochlea filled with fluid that help with balance and hearing. The shape and size of these can tell you a lot about an animal’s behaviour. This, in turn, can help us look at posture – did it change during growth, or during evolution – as well as whether creatures had <a href="https://www.amnh.org/explore/news-blogs/research-posts/desert-dinosaur-likely-hunted-in-the-dark-study-shows">specialised behaviours</a> like burrowing, swimming, flying or extraordinary hearing. </p>
<p>Since the eggs’ discovery in 1976, it was believed that <em>Massospondylus</em> babies hatched on four legs and that, as they grew, they shifted to walk only on their back legs. This has implications for the evolution of posture in dinosaurs. However, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12400">my colleagues and I found</a> that the inner ears of <em>Massospondylus</em> do not show any indications of this shift. </p>
<p>Another way to determine posture in animals is to look at how thick their arm bones (humeri) are compared to their leg bones (femora). Animals that walk on two legs have thicker femora, where they carry all their weight; animals that walk on four legs, meanwhile, distribute their weight evenly, making their humeri almost as thick as their femora. <em>Massospondylus</em> bones <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12451">show</a> that both babies and adults have thicker femora, and that they probably walked on two legs their entire lives.</p>
<h2>More to learn</h2>
<p>Although <em>Massospondylus</em> is teaching scientists a lot about early dinosaur evolution and growth, there is still a lot to learn about it. This includes learning more about the structure of its eggs, how long their incubation period was, or how the rest of the skeleton changed during growth.</p><img src="https://counter.theconversation.com/content/161821/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kimberley E.J. Chapelle received funding from the DSI/NRF Center of Excellence in Paleosciences, the Palaeontological Scientific Trust, the Kalbfleish Fellowship through the Richard Gilder Graduate School of the American Museum of Natural History and the European Synchrotron Radiation Facility.</span></em></p>This is a crucial dinosaur for palaeontologists; the variety of fossils available means researchers can study the species’ growth through its whole life span.Kimberley E.J. Chapelle, Postdoctoral Fellow, Division of Palaeontology, American Museum of Natural HistoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/896152018-01-05T16:00:35Z2018-01-05T16:00:35ZWhy I jumped at the chance to bring the real T. rex to life for TV<figure><img src="https://images.theconversation.com/files/200952/original/file-20180105-26154-1wiqvem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">BBC/Dom Walter, Tailsmith productions</span></span></figcaption></figure><p>The chance to work on a major documentary is always a testing experience for a researcher. It’s a huge opportunity to communicate cutting edge research to the public, but the way the information is presented can lack nuance and detail. This is especially true for dinosaur documentaries that are inevitably watched by young children and have to counter a huge range of myths that have built up in the popular imagination. Trying to educate, inform and entertain the audience all at once is a huge challenge.</p>
<p>Yet when I was invited to become a consultant for <a href="http://www.bbc.co.uk/programmes/b09ksl99">The real <em>T. rex</em> with Chris Packham</a>, I knew it was an opportunity not to be missed. <em>Tyrannosaurus rex</em> is not only the king of the dinosaurs but arguably the most famous animal we only know from fossils. A TV show on this species is an excellent opportunity for outreach and to try to steer conversations away from things like the endlessly recycled, and long ago settled, question of whether <em>T. rex</em> was a <a href="http://www.pnas.org/content/110/31/12560.short">predator</a> or a <a href="http://www.bioone.org/doi/abs/10.4202/app.2009.0133">scavenger</a> (the answer to this is incidentally, both).</p>
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<p>Here I must briefly mention Jurassic Park, even though I’d love not to. When the original film came out in 1993 it did more for getting across then current scientific thinking on dinosaurs than almost anything else ever could. Gone was the image of tail-dragging, upright, lumbering, swamp-dwellers and in came fast, active, and perhaps even intelligent, animals. </p>
<p>This dragged the public image of dinosaurs out of the 1960s and into the 1990s. Unfortunately, another 25 years later the science has moved on again but people’s impressions have not. The challenge is not just to introduce new ideas but overturn old ones.</p>
<h2>Latest research</h2>
<p>In the case of <em>T. rex</em> , we have learned a huge amount in the last 25 years and it has even become something of a model organism for dinosaur researchers. We have new data on their <a href="http://www.bioone.org/doi/abs/10.1666/04044.1?journalCode=pbio">movement</a>, <a href="https://peerj.com/articles/885/">feeding habits</a>, <a href="http://onlinelibrary.wiley.com/doi/10.1002/ar.20983/full">brain and inner ears</a> and more. </p>
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<p>Many of these ideas come from studying incomplete and fragmentary fossils. And however solid the research, this is never going to make exciting viewing. So ideas need to be new, easy to communicate, and contain certain level of whizz-bang for the audience. Access to specimens, and even researchers, for filming can limit the options further.</p>
<p>One excellent example of this was the programme’s section on the tyrannosaur’s bite, with an on-screen comparison with a live alligator. This gave us an opportunity to show off the gator’s bite, which was fun for the audience. But it also meant we could explain or reference the unusual shape of tyrannosaur teeth, the size and shape of their heads, the attachment sites for the jaw muscles, and the evolutionary relationship between crocodilians and dinosaurs.</p>
<h2>Bringing fossils to life</h2>
<p>We also filmed (although it was sadly cut for time from the final show) was a <em>Triceratops</em> pelvis showing <a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.1996.10011297?journalCode=ujvp20">bite marks from a Tyrannosaurus</a>. This allowed us to actually include trace fossils as well. So a single short section covered multiple areas of comparative anatomy, experimental palaeontology, evolution, and ichnology (the study of animal traces like footprints). These were all integrated to build up a single coherent picture of tyrannosaur behaviour, backed by multiple research papers and presented with a bit of flair and easy frame of reference (namely a big alligator).</p>
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<p>In contrast, we had real problems getting the animal’s appearance right because the speed of research outstripped the production. We know several types of tyrannosaur had feathers and researchers have reasonably assumed that <em>T. rex</em> did too. But during production <a href="http://rsbl.royalsocietypublishing.org/content/13/6/20170092">a new paper came out</a> describing some fossilised <em>T. rex</em> skin that showed scales. Although the paper’s authors explicitly didn’t rule out feathers on <em>T. rex</em>, the research obviously meant that we needed to change our initial approach of a near fully feathered dinosaur, to one with a sparser coat.</p>
<p>Documentaries are a great way to potentially reach a huge audience and really engage with the public. The filter of writers, directors, producers and presenters means key messages can go awry, and there will always be compromises and concessions to the practicalities of filming. But the rewards are massive. Just didn’t expect anyone but your family to notice your name in the credits.</p><img src="https://counter.theconversation.com/content/89615/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hone worked as a consultant for The Real T rex with Chris Packham, made by Talesmith Limited for the BBC.</span></em></p>A consultant on Chris Packham’s latest dinosaur show about Tyrannosaurus Rex explains how they kept it entertaining but accurate.David Hone, Senior Lecturer in Zoology, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/786172017-06-08T16:31:58Z2017-06-08T16:31:58ZThe perversion of paleontology by apartheid’s advocates still lingers<figure><img src="https://images.theconversation.com/files/172678/original/file-20170607-11297-11rdzfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Children gather around a fossil skull at a South African museum.</span> <span class="attribution"><span class="source">EPA/Jon Hrusa </span></span></figcaption></figure><p>In 1925, <a href="http://overcomingapartheid.msu.edu/people.php?id=65-251-19">Jan Smuts</a> was both a prominent politician and an advocate for science. Just after the first of his two terms as prime minister of the Union of South Africa, Smuts served as president of the South African Association for the Advancement of Science. It was in this capacity that he spoke out about <a href="http://www.sahistory.org.za/people/raymond-arthur-dart">Raymond Dart’s</a> discovery of <em>Australopithecus africanus</em> and his theories about the <a href="http://humanorigins.si.edu/evidence/human-fossils/fossils/taung-child">Taung skull</a>, saying these ideas meant that</p>
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<p>South Africa may yet figure as the cradle of mankind, or shall I rather, say, one of the cradles?</p>
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<p>He remained in government at the time and actively supported the emerging discipline of paleontology – not just in speeches but in personalised contacts with the scientists who were birthing it. And so, as Christa Kuljan points out in her new book <a href="http://www.jacana.co.za/book-categories/natural-history-a-travel/darwins-hunch-detail">Darwin’s Hunch: Science, Race, and the Search for Human Origins</a>, from the beginning of the search for the “cradle” the role of state support – or lack thereof – was essential to how scientific research was conducted in South Africa. </p>
<p>In the book, Kuljan examines the history of South African palaeoanthropology and genetics research as she tries to make sense of science, race and their links to the hunt for human origins. The “hunch” she refers to was Darwin’s idea, from 1871, that humans evolved in Africa. He was later proved right. But for a long time European scientists rejected his thesis.</p>
<p>As an intellectual history of the disciplines of paleontology and paleoanthropology, Kuljan’s book is especially adept at narrating the interwoven connections between science and power. There are shortcomings, too; she doesn’t really grapple with ideas around identity, and could have explored some scientists’ bizarre preoccupation with Spiritualism in more depth.</p>
<p>The victory of the National Party (NP) in 1948’s elections, as Kuljan shows, threw paleontology into a crisis. This wasn’t only because the effusive support shown by Smuts was lost, but also because the meaning of the word “race” changed to suit the ideological ambitions of apartheid’s advocates. </p>
<h2>The fate of race</h2>
<p>Suspicion and complicity were united under the NP’s rule. Religion rather than science was used as the foundation of race thinking. But at the same time individual scientists – paleoanthropologist <a href="http://www.sahistory.org.za/people/professor-emeritus-phillip-tobias">Phillip Tobias</a> being the most prominent – were repeatedly asked to endorse the existence of “race” and “races”. </p>
<p>Tobias’ behaviour when it came to race was ambiguous.</p>
<p>In 1961 he published a paper titled “<a href="http://www.indiana.edu/%7Eafrcol/items/show/16485">The Meaning of Race</a>” in which he questioned the academic usefulness of the category of race. But at the same time he was leading the “Campbell Griqua Expedition” which exhumed 35 skeletons of people identified as <a href="http://www.sahistory.org.za/article/griqua">Griqua</a>. This was one instance of blatant and criminal “grave digging” by anatomists and paleoanthropologists.</p>
<p>The exhumations reveal a blind spot of the era’s paleontologists, like Tobias – one that even Kuljan does not observe. As far as we know the word “Griqua” is an invention. The people identified by the name are the epitome of hybridity in South Africa. Tobias and his team were looking for “pure Koranna” and “pure Bushman”. They were looking at the “Bushman” once again as the “missing link” – but that’s exactly the opposite of what the Griqua were: from their first appearance on the frontier, they were understood to be a cultural melange of indigenous and enslaved forefathers. </p>
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<p>The failure to really dig into the question of “Griqua” identity is, I think, one of the glaring absences in Kuljan’s account. She could have simply asked the question: what does it mean to erase “hybridity” and replace it with “purity”? By missing this step, the apartheid mania for <a href="https://theconversation.com/the-myth-of-white-purity-and-narratives-that-fed-racism-in-south-africa-59330">racial purity</a> is once again left untouched. </p>
<p>Without this acknowledgement of the irrational, “science” remains “rational” – even while “race” seems to derail its assumptions and unhinge even the most talented minds. </p>
<h2>The metaphysics of science</h2>
<p>This derangement is also evident in the frequency with which believers in the “science of Man” – author J.M. Coetzee’s term for the ethnological disciplines – resorted to Spiritualism. </p>
<p>So, Kuljan writes, both <a href="http://onlinelibrary.wiley.com/doi/10.1002/evan.10024/epdf">John Robinson</a> and <a href="http://www.sahistory.org.za/dated-event/dr-robert-broom-discoverer-mrs-ples-born">Robert Broom</a> – two of South Africa’s most prominent paleontologists – were members or attended the meetings of the mystically-focused <a href="https://www.britannica.com/topic/theosophy">Theosophical Society</a>.</p>
<p>The collision of science and religion caused Robinson to cleave them apart, Kuljan explains, since he saw</p>
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<p>science as explaining the material world, but he looked to his spiritual side to explore non-material aspects of the universe (page 127). </p>
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<p>He went even further by inviting a clairvoyant from New Zealand, Geoffrey Hodson, to Sterkfontein near Johannesburg to channel the life of the “ape-man” via fossils. The <a href="http://www.maropeng.co.za/content/page/explore-the-caves">Sterkfontein caves</a> were quickly becoming the most attractive site for finding fossils. Colloquially, even scientists referred to these fossils as a confirmation of an ancestor who was an “ape-man”. </p>
<p>Robinson invited Hodson to conjure the life of an “ape-man” since this was presumed to be the main characteristic of the human ancestor who became known as <em>Australopithecus africanus</em>. </p>
<p>These and other resorts to metaphysics are not as well explored in the book as they could have been. </p>
<p>It’s not surprising that as human beings scientists can entertain crystal ball visions and table-tapping seances even while claiming to be materialists. The most enduring legacy of these vacillations is that it has bequeathed to us a rather conflicted image of our hominid ancestors.</p>
<h2>African Genesis goes viral</h2>
<p>In Kuljan’s book this conflict revolves around the place of violence in the emergence of homo sapiens. The scientists are not entirely at fault here since it was the sensationalism of Robert Ardrey’s <a href="https://books.google.co.za/books/about/African_genesis.html?id=9Yg1AAAAMAAJ&redir_esc=y">book</a> <em>African Genesis: A Personal Investigation into the Animal Origins and Nature of Man</em> (1961) that catapulted the fragmentary bones and skulls of southern Africa into a full-blown technicolour picture of a hominid ancestor who was a “killer ape”. </p>
<p>This reimagined violent ancestor is still with us not only in the continuing endeavour to “humanise” hominids – the liberal reaction – but also in the visceral <a href="http://www.timeslive.co.za/politics/2015/09/24/Stop-divisive-attacks-over-Homo-naledi-Makhura">attack</a> on the recently discovered <em>Homo naledi</em> by those who think of hominids as “apes”. </p>
<p>Somewhere in between lies the truth of our ancestors. Kuljan’s book is a brave attempt to make this search for our ancestry a recuperable enterprise even while the “killer ape” keeps escaping her scientific confines and invading the imagination of the popular “scientist” and naysayer.</p><img src="https://counter.theconversation.com/content/78617/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hlonipha Mokoena 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>As an intellectual history of the disciplines of paleontology and paleoanthropology, Kuljan’s book is especially adept at narrating the interwoven connections between science and power.Hlonipha Mokoena, Associate Professor at the Wits Institute for Social & Economic Research, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/773452017-05-16T00:14:18Z2017-05-16T00:14:18ZIt’s time to celebrate Africa’s forgotten fossil hunters<figure><img src="https://images.theconversation.com/files/168887/original/file-20170511-32618-bewdt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Local people at Tendaguru (Tanzania) excavation site in 1909 with Giraffatitan fossils.</span> <span class="attribution"><a class="source" href="http://www.welt.de/wissenschaft/article3586616/Urzeitliches-Knochenpuzzle-aus-Deutsch-Ostafrika.html">Wikimedia Commons/Public domain</a></span></figcaption></figure><p>There are few things more exciting for a professional palaeontologist than discovering fossil remains. In early 2017 I found a beautifully preserved skeleton sticking out of the ground in South Africa’s Karoo region. It was the vertebral column of a big herbivorous animal called <a href="http://www.ucmp.berkeley.edu/anapsids/pareiasauria.html">pareiasaur</a>. </p>
<p>The individual vertebral arches were accompanied by the animal’s two hip blades. Fragments of its forelimbs and some parts of its cranium were also visible. All this suggested that I’d found a skeleton nearly 2 meters long, the rest of it hidden below the ground. These 275 million years old fossils had no deformities and were easy to identify. I realised that even someone with no training in palaeontology would have easily find such eroding bones and recognised them as some giant creature’s remains.</p>
<p>This got me thinking about Africa’s earliest fossil seekers, whose identities are largely unknown. Who were they, and how did their discoveries influence our thinking about evolution? How many of their ideas were dismissed or written out of history after the arrival of colonialism and western fossil hunters on the continent? </p>
<p>It’s important to honour these people and their fossil finds, which are examples of both cultural and palaeontological heritage.</p>
<h2>Historical fossil hunting in Africa</h2>
<p>For many, the history of fossil bone discovery in Africa can’t be separated from famous European-led expeditions. Many of these happened during the 19th and 20th centuries and generated breathless headlines around the world. </p>
<p>There was the German expedition at Tendaguru (Tanzania), which yielded the extraordinary skeletons of some of the <a href="https://www.amazon.com/African-Dinosaurs-Unearthed-Tendaguru-Expeditions/dp/0253342147">biggest dinosaurs ever found</a>. American and European palaeontologists also mounted several trips to the <a href="https://link.springer.com/chapter/10.1007/978-0-387-73896-3_9">Fayum depression</a> in Egypt because it was home to mammals of all sorts and sizes some 35 million years ago.</p>
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<a href="https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168366/original/file-20170508-20745-17ek8mu.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">This perfectly preserved backbone actually belongs to a long extinct reptile called pareiasaur.</span>
<span class="attribution"><span class="source">Julien Benoit</span></span>
</figcaption>
</figure>
<p>These expeditions captured the public’s imagination. But the archaeological record reveals that fossils were discovered and collected <a href="http://press.princeton.edu/titles/9435.html">well before such trips</a>, by amateurs who used them in, for instance, religious rituals.</p>
<p>In her book about fossil discoveries in classical Antiquity, “<a href="http://press.princeton.edu/titles/9435.html">The First Fossil Hunters</a>”, Adrienne Mayor mentions that gigantic bones were found in Morocco as early as 300 to 400 B.C. She suspects they were fossilised elephants.</p>
<p>One of the most famous ancient fossil discoveries in Africa involved a giant tooth. Christian theologian and philosopher Saint Augustin, the bishop of what is today Algeria, found it near Utica (Tunisia) in the fourth century A.D. It proved to be a <a href="http://sp.lyellcollection.org/content/310/1/67.abstract">fossilised elephant molar</a>.</p>
<p>Saint Augustin’s discovery isn’t the oldest example of fossil collection in Africa, though. That title goes to the ancient Egyptians who collected and gathered millions of years old mammalian fossil bones and packed them in linen, likely as a <a href="https://books.google.co.za/books?id=9TwhfvU08UcC&source=gbs_book_other_versions">form of worship to Set</a>. These fossil collectors lived 3000 years ago. There’s also evidence of fossilised shark teeth that were collected and pierced to be worn as pendants in ancient Egypt, some <a href="https://books.google.co.za/books?id=9TwhfvU08UcC&source=gbs_book_other_versions">6500 years</a> ago. </p>
<h2>The search for the first fossil collectors</h2>
<p>It’s possible that fossils were recognised in Africa even earlier than this. In Congo, a site dating back 21 000 years has yielded the tooth of a fossil elephant that went extinct millions of years earlier. This <a href="https://books.google.co.za/books?id=9TwhfvU08UcC&source=gbs_book_other_versions">suggests</a> that someone stumbled upon this large fossil tooth and brought it back home, perhaps as a curio.</p>
<p>In addition, an undated Khoisan rock art site in Lesotho appears to represent <a href="http://www.tandfonline.com/doi/pdf/10.1080/10420940591008971">dinosaur footprints</a>. Fossil tracks dating back more than 200 million years ago are not uncommon in this region, and are often well exposed – lying close to the surface of the earth – so it makes sense that ancient residents would have seen and documented them. The Khoisan could well have been the first people to find fossils in Southern Africa. </p>
<p>Though this hypothesis is still <a href="http://www.davidpublishing.com/davidpublishing/Upfile/10/18/2013/2013101882378185.pdf">hotly debated</a>, these drawings are accompanied by cave paintings which suggest the Khoisan interpreted these footprints as belonging to a race of <a href="http://www.tandfonline.com/doi/pdf/10.1080/10420940591008971">giant, flightless birds</a>. Today, most scientists consider birds to be dinosaurs’ closest living relatives. This would imply that Khoisans ancestors had a remarkable sense of scientific reconstruction, even though no framework for evolution had yet been described.</p>
<h2>Before Darwin</h2>
<p>The Khoisan weren’t the only people in Africa thinking way ahead of the Darwinian curve. A number of Muslim scholars from the Middle East and North Africa made very explicit, <a href="https://www.thevintagenews.com/2016/08/27/priority-first-theory-evolution-600-years-older-darwin/">farsighted statements centuries before Darwin</a>.</p>
<p>For example, a Tunisian scholar named Ibn Khaldun, stated as early as 1377 that “the higher stage of man is reached from the world of the monkeys, in which both sagacity and perception are found.” He was probably inspired by his predecessor, the Persian Ibn Miskawayh (932-1030), who stated in the Brethren of Purity that “Animalilty […] finally reaches the frontier of humanity with the Ape which is just a degree below Man in the <a href="http://pu.edu.pk/images/journal/uoc/PDF-FILES/%2811%29%20Dr.%20Sultan%20Shah_86_2.pdf">scale of evolution”</a>.</p>
<p>It’s very likely that Darwin didn’t know about these ancient discoveries and medieval authors since they are not mentioned in any of his biographies or works. But the very fact that they exist illustrates Africa’s formidable potential to influence and develop palaeontological research. </p>
<p>The challenge now is to build upon this heritage and raise awareness about these long-forgotten discoveries and theorists. This is an important way to motivate a new generation of African fossil researchers.</p><img src="https://counter.theconversation.com/content/77345/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>Africa has one of the world’s richest fossil records, and evidence suggests that amateurs collected really important fossils long before professionals arrived on the scene.Julien Benoit, Postdoc in Vertebrate Palaeontology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/554602016-02-29T20:02:11Z2016-02-29T20:02:11ZOur 500 million-year-old nervous system fossil shines a light on animal evolution<figure><img src="https://images.theconversation.com/files/113080/original/image-20160226-26697-6aus2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jie Yang (Yunnan University, China)</span></span></figcaption></figure><p>The nervous system is the command centre of an animal’s body, carrying all the complex electrical signals for the actions that keep it alive, such as moving and eating. Because of its critical function, the nervous system also contains a lot of information about an animal’s evolution, and can even help us understand how different groups relate to each other. But preserved fossilised nervous systems from extinct creatures are extremely rare. </p>
<p>That’s why my colleagues and I <a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1522434113">were excited to discover</a> one of the most detailed and well-preserved nervous system fossils ever found, from a crustacean-like animal known as a fuxianhuiid that lived more than 500m years ago. These fossils – which come from the Xiaoshiba biota in south China – are so well preserved that you can see individual nerve roots ten times thinner than a human hair. The findings offer the most detailed view of the nervous system in early animals available to date, and inform us about the early evolution of the nervous system in these creatures and their close relatives. </p>
<h2>Ancient arthropod</h2>
<p>The fuxianhuiids (pronounced foo-see-an-who-eeds) were primitive animals known only to have lived during the early Cambrian period in China, some 515-520m years ago. Fuxianhuiids are widely regarded as being important for understanding the early evolution of <a href="https://theconversation.com/fossils-of-huge-plankton-eating-sea-creature-shine-light-on-early-arthropod-evolution-38520">the arthropods</a>. This is a large group of animals with jointed limbs and hard exoskeletons that also includes insects, arachnids and crustaceans. So finding preserved nervous tissues in fuxianhuiids tells us a lot about their early evolution and that of their close relatives.</p>
<p>By painstakingly chipping away small pieces of rock from the fossil using a fine needle, my colleagues in China were able to reveal the ventral nerve cord running through their entire body. The ventral nerve cord is part of the nervous system, very much similar to our spinal cord, and it resembles a string of beads.</p>
<p>Each of the “beads” actually corresponds to a ganglion, a condensed mass of nerve cells whose function is to control the legs on each segment of the body in fuxianhuiids and other arthropods. Our fossils also preserve dozens of delicate nerves that emerge at either side of the ventral nerve cord and that would have been connected to the legs and other parts of the body. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=768&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=768&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=768&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=965&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=965&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113083/original/image-20160226-26697-4mnguh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=965&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ventral cord.</span>
<span class="attribution"><span class="source">Jie Yang (Yunnan University, China) (left) and Javier Ortega-Hernández (University of Cambridge, UK)</span></span>
</figcaption>
</figure>
<p>Finding the fossilised remains of an animal’s nervous system is extremely unusual, as the brain and ventral nerve cord are mainly made of fatty tissues and decay very quickly under normal circumstances. But under exceptional conditions – such as very rapid burial in environments with little oxygen – these delicate structures can be preserved in the fossil record.</p>
<p>In the last five years, <a href="http://linkinghub.elsevier.com/retrieve/pii/S0960982215004856">various studies</a>, have reported the <a href="http://rstb.royalsocietypublishing.org/content/370/1684/20150038.abstract">preservation of brains</a> in Cambrian arthropods, which has greatly improved our understanding of their evolution. But in most cases, we can only recognise the broad outline of the brain and so there are limits to the information that can be extracted from the fossils. Our study is the first time that a complete ventral nerve cord has been described in such an extraordinary level of detail.</p>
<p>More importantly, the ventral nerve cord of fuxianhuiids is rather unique among arthropods. Whereas most arthropods also possess condensed ganglia, they generally lack the dozens of delicate nerve roots that are found in fuxianhuiids. However, this peculiar organisation can be found in <a href="https://www.youtube.com/watch?v=IWcGzxyqiUM">velvet worms (or onychophorans)</a>, a group of animals resembling worms with legs that are cousins to the arthropods. So the fuxianhuiid ventral nerve cord is an intermediate between the nervous system of arthropods and velvet worms.</p>
<h2>Common ancestral link</h2>
<p>This means we can interpret the dozens of nerves in fuxianhuiids as an ancient trait inherited from the last common ancestor between velvet worms and arthropods. This is similar to how the feet of modern birds resemble the feet of dinosaurs, because they were also inherited from their <a href="http://www.livescience.com/3946-early-birds-dinosaur-feet.html">last common ancestor</a></p>
<p>By contrast, the presence of ganglia on the nerve cord of fuxianhuiids is an innovation that occurred in the evolution of arthropods. Keeping with the analogy, this is like how feathers are an innovation that occurred in <a href="http://ngm.nationalgeographic.com/2011/02/feathers/zimmer-text">the evolution of birds.</a></p>
<p>The most interesting conclusion we can draw is that the origin of the arthropod nervous system required the dramatic reduction in the number of nerves, and that this event took place after the early Cambrian period. Without fuxianhuiids, it would have been impossible to attain this depth of knowledge on the evolution of the nervous system.</p><img src="https://counter.theconversation.com/content/55460/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Javier Ortega-Hernandez receives funding from Emmanuel College and a Herchel-Smith Postdoctoral Fellowship, both from the University of Cambridge, UK. </span></em></p>Scientists have uncovered one of the most detailed and well-preserved nervous system fossils ever found.Javier Ortega-Hernandez, Research fellow in palaeobiology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/529112016-01-08T13:12:14Z2016-01-08T13:12:14ZMysterious footprint fossils point to dancing dinosaur mating ritual<figure><img src="https://images.theconversation.com/files/107659/original/image-20160108-3334-gdk2gs.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tyrannosaurus tango</span> <span class="attribution"><span class="source">Xing Lida and Yujiang Han</span></span></figcaption></figure><p>Studying dinosaurs is a lot like being a detective. Just as Sherlock Holmes was noted for his ability to interpret the behaviour of victims or criminals using footprints, palaeontologists have a similar practice when looking for evidence of dinosaur behaviour known as ichnology.</p>
<p>This is the study of the traces living organisms leave behind including bones, footprints and even bite marks on leaves. Indeed, Sherlock Holmes’ creator, Sir Arthur Conan Doyle, was <a href="https://books.google.co.uk/books?id=kji6fde5g-gC&pg=SL26-PA1&lpg=SL26-PA1&dq=conan+doyle+dinosaur+footprint+beckles&source=bl&ots=g1gpnVvSkW&sig=j6w-TmfTXyZv0z3C5NECPSS2vKs&hl=en&sa=X&ved=0ahUKEwiQz8-RmZrKAhWIVhoKHfkNDrIQ6AEIIDAA#v=onepage&q=conan%20doyle%20dinosaur%20footprint%20beckles&f=false">very well aware</a> of the traces of dinosaur footprints that had been discovered in the rocks of the Weald near his home in south-east England.</p>
<p>Now researchers in the US have discovered some very unusual trace fossils they believe could also be footprints. Although it is far from certain, these markings may provide the first clue as to whether dinosaurs performed dance-like mating rituals similar to those of living birds.</p>
<h2>Scratching the surface</h2>
<p>The team from the University of Colorado Denver <a href="http://www.nature.com/articles/srep18952">have unearthed</a> some truly extraordinary trace fossils on the bedding surfaces of sedimentary rocks of Cretaceous age in Colorado. The bedding surfaces have revealed an irregular array of large scoop-shaped depressions up to 2m in diameter and adjacent hummocks. Many of the scoops also display clear and unequivocal elongate scratch marks.</p>
<p>Given the geological ages of these rocks, the only large, powerful ground-dwelling creatures likely to be able to make such structures would have been dinosaurs. These curious sedimentary structures are not simply a one-off isolated discovery that can be explained as just a weird bit of geology, but have been found in clusters at a number of discrete sites across Colorado. Each site has a rather similar, comparatively dense, cluster of these scoop-like structures.</p>
<p>At first sight it would be perfectly reasonable to consider that such structures were the remnants of ancient dinosaur nests. Dinosaur nest sites, including eggs, shell fragments and even nestling dinosaur remains are comparatively well known. They <a href="http://www.nature.com/nature/journal/v378/n6559/abs/378774a0.html">have been reported</a> from a range of Cretaceous aged sites that have been found in North America, South America and Asia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=419&fit=crop&dpr=1 600w, https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=419&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=419&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=527&fit=crop&dpr=1 754w, https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=527&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/107660/original/image-20160108-3345-mjbkwx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=527&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dinosaur detectives.</span>
<span class="attribution"><span class="source">M. Lockley</span></span>
</figcaption>
</figure>
<p>But these “scoops and hummocks” differ in their detailed structure when compared to definitive dinosaur nests. Dinosaur nests <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4428272&fileId=S0016756800011547">tend to be</a> circular, rather flat-bottomed, usually have traces of egg shell and are typically surrounded by a rim-like perimeter wall.</p>
<p>In fact, these new and distinctive structures show no evidence of what appear to be conventional dinosaur nest structure or scattered egg shell fragments. They are elongate, concave depressions with sediment clearly heaped to one side. In many instances, they display scrape marks that appear to have been made by dragging claws.</p>
<p>These structures are most comparable to the “leks” produced by living ground-nesting birds. Leks are effectively display arenas in which <a href="https://theconversation.com/five-lessons-in-seduction-from-the-males-of-the-animal-kingdom-52118">male birds</a> perform a courtship ritual that can include dancing, showing off their feathers and making calls to attract the attention of nearby females.</p>
<p>The researchers suggest the geological structures were originally created by theropods, the group of dinosaurs most closely <a href="https://theconversation.com/six-amazing-dinosaur-discoveries-that-changed-the-world-51367">related to living birds</a> and which includes <em>Tyrannosaurus Rex</em>. <a href="http://www-hsc.usc.edu/%7Ecmchuong/2014Birdorig.pdf">Theropods may well</a> have been very like modern birds in their behaviour and made the scrapes as part of the production of a display arena for courtship. However, it seems likely that if these marks were leks they would have been next to actual breeding/nesting sites, but so far no trace of nests has been discovered.</p>
<h2>Tracking down Cinderella</h2>
<p>The frustrating thing about ichnology is that while the tracks and traces left by living creatures can be matched to observations of their actual behaviour, this is rarely the case when it comes to the fossilised traces of dinosaurs. Trying to tie the identity of fossilised tracks to the original track-maker has been a persistent problem for palaeontologists. It’s rather like the hunt for Cinderella: they have to look for animals that lived at the exact time the tracks were formed, with feet bones the right size and shape to precisely fit the shoe of the fossilised footprint.</p>
<p>Fossilised tracks and traces used to be <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4423968&fileId=S0016756800010050">rather disparaged</a> by palaeontologists because the difficulties surrounding the identity of the actual track-maker seemed more or less insurmountable. However, the past few decades has seen a growing appreciation of the information that can be gleaned from such tracks and traces.</p>
<p>This includes the local environmental conditions when the tracks were made, the texture of the sediments that the creature was walking upon, and the details of foot placement, stride length and stride pattern. These can reveal a surprising amount of information about the way the track-maker walked, its posture and even the likely speed at which it was moving – very reminiscent of the skills demonstrated by Conan Doyle’s heroic sleuth.</p>
<p>Just a few years ago the question of bird-dinosaur affinities was also a topic that was very hotly disputed. The discovery of <a href="http://www-hsc.usc.edu/%7Ecmchuong/2014Birdorig.pdf">feathered theropods</a> in the 1990s finally proved that theropod dinosaurs were ancestral to living birds. Although we can’t yet be sure, the new research suggests some dinosaurs may have been not just anatomically similar to birds but also have shared some mating behaviours. This gives rise to the amusing possibility of a dancing <em>T. Rex</em> trying to impress his potential mate.</p><img src="https://counter.theconversation.com/content/52911/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Norman 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>Researchers believe newly uncovered fossils suggest some dinosaurs had similar courtship practices to modern birds. But can ancient footprints really reveal so much?David Norman, Reader in Paleobiology, Curator of Palaeontology, Sedgwick Museum of Earth Sciences, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/504162015-11-25T12:33:43Z2015-11-25T12:33:43ZHomo naledi may be two million years old (give or take)<figure><img src="https://images.theconversation.com/files/101607/original/image-20151111-9400-17a11sc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Professor Lee Berger from the University of the Witwatersrand holding the skull of Homo Naledi.</span> <span class="attribution"><span class="source">EPA/Shiraaz Mohamed</span></span></figcaption></figure><p>There has been global interest in the announcement of new fossils from a cave called Rising Star in the <a href="http://www.maropeng.co.za/videos/entry/sterkfontein-caves-unesco-world-heritage-site">Cradle of Humankind World Heritage Site</a> in South Africa.</p>
<p>These fossils were recently reported by <a href="http://dx.doi.org/10.7554/eLife.09560">Lee Berger</a> and his team, who described the discovery of more than 1500 fossils as representing a new species of the genus Homo. It has been called Homo naledi, associated with a name for star in the Sesotho language.</p>
<p>But the age of Homo naledi is not yet known with certainty. The new species has not yet been dated. Unsuccessful attempts had been made by <a href="http://dx.doi.org/10.7554/eLife.09561">Paul Dirks</a> and members of the Rising Star team to obtain an age. They used techniques applied previously to date a range of fossils. These included Australopithecus africanus, such as the famous <a href="http://www.encounter.co.za/article/58.html">“Mrs Ples”</a> skull, as more than two million years old, and fossils of <a href="http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-robustus">Paranthropus</a> robustus and <a href="http://www.livescience.com/41048-facts-about-homo-erectus.html">Homo erectus</a>.</p>
<p>In a new <a href="http://www.sajs.co.za/sites/default/files/publications/pdf/SAJS%20111_11-12_Thackeray_Sci%20Cor.pdf">paper</a> in the South African Journal of Science I suggest that Homo naledi lived two million years ago (plus or minus 500,000 years). If shown to be correct, this will help to place Homo naledi in the family tree of human relatives.</p>
<p>The variance is based on the fact that the earliest date for Homo rudolfensis is about 2.5 million years, and the date for certain African Homo erectus samples is about 1.5 million years.</p>
<p>Although different, Homo naledi is most similar to fossils attributed to Homo habilis (about 1.8 million years old), and to a lesser extent to fossils of Homo rudolfensis and Homo erectus.</p>
<p>Taken together I am suggesting that Homo naledi is in the order of two million years old, with upper and lower limits of about 1.5 and 2.5 million years respectively. </p>
<h2>Why is dating so important</h2>
<p>Estimating the age of <a href="http://antiquity.ac.uk/projgall/thackeray335/">fossils</a> is important because it allows palaeoanthropologists the opportunity to try to draw up a family tree. It shows the evolutionary relationships of distant relatives.</p>
<p>Some of the fossil species can be considered to represent possible ancestors of our own species, Homo sapiens, while other species such as <a href="http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-robustus">Paranthropus</a> robustus can be considered to be evolutionary “dead ends”.</p>
<p>The big question being asked is: where does Homo naledi fit in the evolutionary tree?</p>
<p>It had a small brain of about 500 cubic centimetres in volume. This makes it similar to fossils of Australopithecus. On the other hand, bones of parts of the skeleton, especially the foot, indicate that this species was in some respect remarkably like Homo. </p>
<p>Dating such enigmatic fossils is crucial for an understanding of evolutionary relationships of Homo naledi, compared to more than ten other species which are recognised by palaeontologists.</p>
<p>My approach has been to assess the degree of similarity or dissimilarity between skulls. This can help to assess the age and affinities of fossils.</p>
<h2>Quantifying degrees of similarity between fossils</h2>
<p>Recognising that the new fossils have features of both Australopithecus and Homo, we need to know how old they are. One way of addressing this is to use a technique that I have previously described, based on measurements of <a href="https://theconversation.com/species-without-boundaries-a-new-way-to-map-our-origins-42646">skulls</a>.</p>
<p>Statistics are calculated by taking one set of measurements for specimen A, plotted against the corresponding measurements of specimen B. When A and B are the same species, the values for the two specimens are typically distributed along a straight line, with little scatter around that linear pattern. </p>
<p>When measurements of two specimens (C and D) of different species are plotted against each other, there is a high degree of scatter. The degree of scatter around the line can be quantified using a statistic that I have called log sem, based on a standard mathematical technique that is known as least squares linear regression. </p>
<p>Remarkably, a pattern has been found for comparisons of modern skulls of the same species, whether these are of mammals, birds or reptiles. The mean log sem value for comparisons of pairs of modern species has central tendency around a particular number with a value of -1.61 (plus or minus 0.1), which I have regarded as an approximation of a biological species constant called <a href="http://www.scielo.org.za/pdf/sajs/v103n11-12/a0210312.pdf">T</a>.</p>
<h2>How does this help to date Homo naledi</h2>
<p>Comparisons have been made between the skull measurements of Homo naledi and those of more than ten other recognised species. </p>
<p>It is possible to say that Homo naledi is indeed different because in all cases the log sem statistics for such comparisons is significantly greater than -1.61. </p>
<p>But what is exciting is the fact that of all such comparisons, Homo naledi is most similar to skulls attributed to Homo habilis known to date to about 1.8 million years, and to some extent to other fossils attributed to Homo rudolfensis between about two and 2.5 million years ago.</p>
<p>To a smaller extent Homo naledi is similar to fossil skulls of Homo erectus between about 1.5 and 1.8 million years ago. Using these results, based on comparisons of skulls, I suggest that Homo naledi is two million years old, plus or minus 500,000 years.</p><img src="https://counter.theconversation.com/content/50416/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Francis Thackeray received funding for this study from the National Research Foundation and the A.W. Mellon Foundation</span></em></p>The big question being asked is: where does Homo naledi fit in the evolutionary tree? Assessing the similarity or dissimilarity between fossil skulls has provided a possible clue to the answer.Francis Thackeray, Phillip Tobias Chair in Palaeoanthropology, Evolutionary Studies Institute, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/443672015-07-08T04:21:12Z2015-07-08T04:21:12ZUnraveling the mystery of how dinosaurs get their names<figure><img src="https://images.theconversation.com/files/87667/original/image-20150707-1291-1jeh74b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What's in a name? Plenty, if it is a dinosaur such as the Changyuraptor, a genus of the 'four-winged' predatory dinosaur.</span> <span class="attribution"><span class="source">S. Abramowicz, Dinosaur Institute</span></span></figcaption></figure><p>Many kids can recite an A-Z list of dinosaur names. They take special delight in defeating tongue-twisters like <em>Carcharodontosaurus</em>, <em>Ekrixinatosaurus</em>, <em>Huehuecanauhtlus</em> and <em>Zuchengtyrannus</em>. </p>
<p><a href="http://www.nhm.ac.uk/nature-online/science-of-natural-history/biographies/richard-owen/">Sir Richard Owen</a> came up with the name <a href="http://wonderopolis.org/wonder/how-do-dinosaurs-get-their-names/">dinosaur</a> in 1841 to describe the fossils of extinct reptiles. He coined the word by combining the Greek words “deinos”, which means terrible, and “sauros”, which means lizard.</p>
<h2>What lies behind a name</h2>
<p>A dinosaur’s name says something about the dinosaur itself. Scientists often use Greek or Latin root words to give a name that describes the dinosaur in some way.</p>
<p>Dinosaurs, like all living organisms, are classified or grouped together according to similarities they share, which also indicates their ancestral relationships to one another. To do this objectively, scientists apply cladistics, a <a href="http://www.enchantedlearning.com/subjects/dinosaurs/dinoclassification/Classification.html">methodology</a> that enables the assessment of relationships of organisms to one another based on shared characteristics. </p>
<p>According to the classification system, there are always two parts to a dinosaur’s name – or any living organism for that matter – and they should both be italicised. The first part of the name is called the genus name and the second the species name. </p>
<p>There can be several different species (varieties) of a particular genus of an animal. For example, humans are <em>Homo sapiens</em>, but in the fossil record there are several other members of the genus <em>Homo</em> for example <em>Homo neanderthalensis,</em> and <em>Homo erectus</em> .</p>
<p>Before it can become official, and to prevent duplication, once palaeontologists have chosen a new name it has to be approved by the <a href="http://iczn.org/content/about-iczn">International Commission on Zoological Nomenclature</a>. Palaeontologists must also fully describe the anatomy of the dinosaur and explain the cladistic analyses and the derivation of the name in a peer-reviewed academic journal. </p>
<h2>Who gets to have a dinosaur named after them</h2>
<p>Only a few palaeontologists ever have the opportunity of naming a dinosaur, and even fewer have species named after them. Paleontologists get to name a dinosaur if they, or an expedition team, finds an animal that is distinct from any others known.</p>
<p>Occasionally the remains of a dinosaur may have been excavated a long time ago, but subsequent investigations reveal that it is in fact a new dinosaur. This is the case of <em>Sefapanosaurus zastronensis</em>, South Africa’s most recently named dinosaur which was excavated more than 80 years ago close to Zastron, a small town near South Africa’s border with Lesotho. At the time it was collected it was unnamed. Later scientists studied the bones cursorily and considered them to be like that of another early dinosaur called <em>Aardonyx</em> . </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=231&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=231&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=231&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=291&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=291&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87651/original/image-20150707-1311-1rtmt6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=291&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Meet South Africa’s most recently named dinosaur, Sefapanosaurus zastronensis, which was excavated more than 80 years ago close to Zastron.</span>
<span class="attribution"><span class="source">Alejandro Otera</span></span>
</figcaption>
</figure>
<p>But the material was recently re-examined and found to be quite unlike any of the known contemporary dinosaurs.</p>
<p>Given that its ankle bone had a very unusual cross shape we decided to <a href="http://onlinelibrary.wiley.com/doi/10.1111/zoj.12247/full">name</a> the dinosaur after this feature and to give it a Sesotho name, since this is the language prevalent in the area. Thus <em>Sefapanosaurus</em> is derived from “sefapano” which means “cross” in Sesotho and “saurus” which is Greek for “lizard”. The second part is derived from Zastron. </p>
<p>Like <em>Sefapnosaurus</em>, many dinosaurs are named for particular features in their skeletons. For example, last year, I was fortunate to be part of the team that <a href="http://mg.co.za/article/2014-07-15-winged-changyuraptor-adds-feather-to-sa-scientists-cap">named</a> a rare four-winged, long-tailed dinosaur from northeastern China, <em>Changuraptor</em>. “Changu” means “long feather” in Chinese, and “raptor” refers to its predatory habits. The second part of the name honours Yang Yandong, chairman of Bohai University, who provided funding to obtain the specimen.</p>
<p>There is a curious story about a Southern African predatory dinosaur called <em>Syntarsus</em>. Thirty-two years after it was named entomologist realised that the name was already given to a beetle in 1869 and they renamed the dinosaur, much to our dismay, <em>Megapnosaurus</em>, which means “big dead lizard”.</p>
<p>Another South African dinosaur, which we <a href="http://www.uct.ac.za/dailynews/?id=7177">named</a> in 2010, is <em>Aardonyx celestae</em>. This dinosaur’s name has its roots in Afrikaans (“aard” means earth) and Greek (“onyx” means claw), and refers to the fact that the animal had thick iron rich sediments, or hematite, surrounding many of its foot bones. The second part of the <em>Aardonyx</em> name pays tribute to Celeste Yates, who as a volunteer did the laborious, painstaking preparation of the fossils by removing the surrounding rock matrix in which they were embedded.</p>
<p>Ten years ago I was also part of the team that <a href="http://www.bioone.org/doi/abs/10.1671/0272-4634(2000">named</a> <em>Nqwebasaurus thwazi</em>, the first isi-Xhosa-named dinosaur. This dinosaur was discovered from the Kirkwood cliffs near Grahamstown in the Eastern Cape by my colleagues, Billy De Klerk from the Albany Museum and Callum Ross from the US. In isi-Xhosa, the Kirkwood region is known as “Nqweba”. “Thwazi” means fast-runner.</p>
<p>I have also had the privilege of being on the team that <a href="http://www.bioone.org/doi/abs/10.1080/02724634.2013.762708">named</a> <em>Zhouornis hani</em>, a large Mesozoic bird from China. In this case, the early bird is named after Zhou Zhonghe, a Chinese palaeontologist who has made a huge contribution to studies about the early evolution of birds. The species name honours the collector of the specimen, Lizhuo Han.</p>
<p>All dinosaur names have a particular meaning. It is fascinating to understand the derivation of their names, and to learn of the sometimes quirky stories behind them.</p><img src="https://counter.theconversation.com/content/44367/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anusuya Chinsamy-Turan receives funding from the National Research Foundation.</span></em></p>A dinosaur’s name says something about the dinosaur itself. They are grouped together according to similarities they share, which also indicates their ancestral relationships to one another.Anusuya Chinsamy-Turan, Professor, Head, Biological Sciences Department, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.