“Antarctic King”: iguana-sized dinosaur cousin discovery
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Antarctica wasn’t always a frozen wasteland – some 250 million years ago, it was covered in forests and rivers, and the temperature rarely dipped below freezing. Antarctica was also home to diverse wildlife, including early relatives of the dinosaurs – and scientists, including Iziko Museums of South Africa’s Prof Roger Smith, have just discovered the newest member of that family – an iguana-sized reptile whose name means “Antarctic King”.
In a global partnership between Iziko Museums of South Africa, the University of the Witwatersrand, Burke Museum, University of Washington and the Field Museum, Chicago – a team of scientists have described the new species of archosaur, which they have identified as an early relative of crocodiles and dinosaurs. Appearing in the Journal of Vertebrate Palaeontology, lead author Dr Brandon Peecook alongside his co-authors; Prof Roger Smith and Christian Sidor, claim that the find is one of the first members of the archosaur group – informing us how dinosaurs and their closest relatives evolved and spread.
According to Prof Smith, “one of the main reasons for searching for fossils in Antarctica is that they can tell us what life forms lived on this, now, inhospitable continent millions of years ago. This new find in Antarctica sheds more light on how and where the ancestors to dinosaurs survived a volcanically-induced catastrophic global warming episode that caused the End-Permian Mass Extinctions. As such, Antarctanax is a key fossil in this lineage towards dinosaurs (and birds), and it is possible that the sub-Antarctic polar habitat, in the earliest Triassic period, was a refuge for land animals that were dying-out in the rest of the world.”
“Antarctica was originally joined to South Africa as part of the Gondwana supercontinent, and only became separated some 150 million years ago,” says Smith, who has spent 40 years researching the rocks and reptile fossils of the South African Karoo. “Before the ‘break-up’, animals and plants were able to colonise the lowlands all along thesouthernmargin of Gondwana, so that today we find some fossil species in the rocks of the Trans-Antarctic Mountains that are identical to those in the South African Karoo.” Over the past 15 years, Prof Smith has taken part in three, three-month-long expeditions to the Trans-Antarctic Mountains. In January 2011– on his 60th birthday – he spotted a number of small, long and slender bones in a rock exposure halfway up Graphite Peak, near Beardmore Glacier in Antarctica.
Smith excavated the bones with a hammer and chisel in temperatures dropping below -25⁰C, and – back in Seattle, at the University of Washington the bones were assembled and identified by Dr Brandon Peecook as a new type of archosaur. The fossil skeleton is incomplete, but palaeontologists still have a good feel for the animal named Antarctanax shackletoni – the former means “Antarctic King”, and the latter a nod to polar explorer, Ernest Shackleton.
Based on its similarities to other fossil animals, Peecook and his co-authors surmise that Antarctanax was a carnivore that hunted bugs, early mammal relatives, and amphibians. The most interesting thing about Antarctanax is where it lived and when. It was assumed that Antarctic animals would be similar to the ones that were living in southern Africa – considering that those landmasses were joined millions of years ago as the continent of Gondwana. However, these scientists have found that Antarctica’s wildlife is surprisingly unique.
About two million years before Antarctanax lived – the blink of an eye in geological time – the Earth underwent its biggest-ever mass extinction. Climate change, caused by volcanic eruptions, killed 90% of all animal life. The years immediately after this extinction were an evolutionary ‘free-for-all’ – where new groups of animals vied to fill the gaps left by those wiped out. The archosaurs, including dinosaurs, were one of the groups that experienced enormous growth.
“Before the mass extinction, archosaurs were only found around the Equator, but after it, they were everywhere,” says Peecook. “And Antarctica had a combination of these brand-new animals and stragglers of animals that were already extinct in most places – what palaeontologists call ‘dead clades walking’. You’ve got tomorrow’s animals and yesterday’s animals cohabiting in a cool place.”
The fact that scientists have found Antarctanax helps bolster the idea that Antarctica was a place of rapid evolution and diversification after the mass extinction. “The more different kinds of animals we find, the more we learn about the pattern of archosaurs taking over after the mass extinction,” notes Peecook.
In likeness to the bottom of the ocean, Antarctica is a space on Earth where scientists are still in the very early stages of exploration – and the Antarctanax is Smith’s, Peecook’s and Sidor’s little part of discovering the history of Antarctica.
Image 1:iziko_Prof Roger Smith on Graphite Peak-theday he discovered the new archosauromorph fossil-his 60th birthday present
Image 2:Antarctanax fossil 2, (c) Brandon Peecook, Field Museum
Image 3:Antarctanax fossil 1, (c) Brandon Peecook, Field Musuem
Image 4:Antarctanax illustration (c) Adrienne Stroup, Field Museum
Issued by: Ellen Agnew
Communications Coordinator: Iziko Museums of South Africa
Telephone: 021 481 3830
Issued on behalf of the Office of the CEO, Iziko Museums of South Africa
About Iziko Museums of South Africa (Iziko)
Iziko operates 11 national museums, the Planetarium and Digital Dome, the Social History Centre and three collection-specific libraries in Cape Town. The museums that make up Iziko have their own history and character, presenting extensive art, social and natural history collections that reflect our diverse African heritage. Iziko is a public entity and public benefit organisation that brings together these museums under a single governance and leadership structure. The organisation allows *free access to all individuals on commemorative days, (*excluding the Castle of Good Hope, Groot Constantia and Planetarium and Digital Dome). Visit our webpage at http://www.iziko.org.za, join our online community on Facebook (http://www.facebook.com/IzikoMuseums) or follow us on Twitter (@Iziko_Museums) for regular updates on events, news and new exhibitions.