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Rare fossils of Triassic reptiles found in Antarctica

Artist picture Antarctanax Shackleton (left). Through the brook, a large Archosaur pursues a pair of unsuspecting Dicynodonts.
Image: Adrienne Stroup, Field Museum

The fossil remains of an early reptile, dating back about 250 million years, were found in the most unexpected places: Antarctica. This discovery shows how wildlife has recovered from the worst mass extinction in the history of our planet, and how the Antarctic once had an ecosystem, unlike any other.

Needless to say, paleontological work in Antarctica is very different from others. Unlike Alberta or Montana, for example, which have extensive rocky outcrops, Antarctica is covered with a massive layer of ice, hiding most of its paleontological history. And the point is not that Antarctica has no stories to tell, but very many. Only recently, during the last 30–35 million years, has the continent froze. Prior to this, there was a warm climate, lush forests, turbulent rivers and a wonderful abundance of life.

To find the fossil traces of this forgotten life, whether in Antarctica or anywhere else, scientists need to find stones. Antarctica provides only two possibilities: the islands along its coastline and the Central Transantarctic Mountains – the top of the mountains, cutting a strip through the middle of the continent. The tops of these mountains penetrate the glaciers, creating a rocky archipelago — and a place for paleontologists to do some research. It was here, in the Fremou Formation of the Transantarctic Mountains, that Brandon Pikuk, a paleontologist at the Field Museum of Natural History and the lead author of a new study, discovered a rare Triassic reptile.

“Standing on a mountain, it was difficult to imagine how then truly alien Antarctica looked,” said Pikuk Gizmodo. “Looking around, I did not see any trace of macroscopic life for miles in every direction.”

Brandon Pikuk conducts exploration in Antarctica.
Image: Roger Smith

Indeed, Antarctica today may be desert and inhospitable, but it was not always like this. Hundreds of millions of years ago, the Fremoe Formation was home to a vibrant, life-filled forest, from winged insects to four-legged herbivorous reptiles. The discovery of a previously unknown reptile the size of an iguana, called Antarctanax Shacletonicurrently adds to our knowledge of the past ecological glory of the continent.

Antarctanax means "Antarctic King" and shackletoni This is the hat of the British polar explorer Ernest Shackleton. A. Shackletoni He was an archosaur who shared a common ancestor with dinosaurs and crocodiles and who lived at the beginning of the Triassic period about 250 million years ago. Now it is one of the earliest lizards that appeared in the fossils. Details of this discovery were published today in the journal Vertebrate Paleontology.

The partial fossil consists of perfectly preserved vertebrae (including the neck and back), a partial skull, two legs, some ribs and bones of the forearm. It was discovered during an expedition to the Fremok Formation in the summer of Antarctica in the years 2010-2011. Analysis of these fossil bones (especially the skull) and the fossils found next to it suggests that it was a pint-sized predator chewing insects, amphibians and early proto-mammals. Roger Smith from the University of Witwatersrand in South Africa and Christian Sidor from the University of Washington in Seattle helped Peecook with the analysis.

Fossil side showing vertebrae and arm bone.
Image: Brandon Pikuk, Field Museum

The early Triassic is of great interest to paleontologists, because it occurred after one of the worst episodes in the history of Earth – a mass extinction at the end of Perm, when extreme and prolonged volcanism destroyed almost 90 percent of the life of our planet. This led to a radical ecological reboot, setting the stage for survivors. Among these survivors were archaurs, who took full advantage.

“The model that we see again and again with riots, such as the mass extinction at the end of Perm, is that some animals that survived quickly filled out the empty ecospace,” said Pikuk Gizmodo. “Archosaurs are a great example — a group of animals that could do almost everything. This treasure has become just ballistic.

The opposite side of the fossil, showing several vertebrae, ribs and right leg.
Image: Brandon Pikuk, Field Museum

Indeed, Archosaurs, including dinosaurs, were among the greatest beneficiaries of this recovery period, experiencing tremendous growth and diversity. Before the mass extinction, these creatures were limited to equatorial regions, but subsequently they were “everywhere”, according to Pikuk, including, as we now know, Antarctica. The continent was home to A. Shackletoni about 10 million years before the advent of the real dinosaurs. In addition, Antarctica hosted dinosaurs, but only until the Jurassic period.

This discovery also sheds light on the characteristic animals of Antarctica. Since Antarctica and South Africa were physically connected at the time, paleontologists worked on the assumption that these two regions have much in common with the point of view of local wildlife. And since there are many fossils in South Africa, paleontologists used this record to draw conclusions about what kind of life probably existed in Antarctica. But, as Peecook explained, this turns out to be a mistake; In Antarctica was the ecology, not unlike any other.

“We really know the fossils of South Africa, but in Antarctica we only found about 200 species,” he said. “But we cannot find these species anywhere else. Paleontologists have been to Antarctica only a few times, but every time they come, they find new species and surprise new phenomena – this is really exciting. The initial argument that you can connect these two environments together is now incorrect. There are many unique things happening in the Antarctic report. ”

The fact that in Antarctica a unique set of species is presented is not surprising. Like today, the continent was at a high altitude, with extended days in summer and extended nights in winter. Animals and plants had to adapt in order to survive, thereby applying new physical characteristics and survival strategies.

The mind is astounded at the thought of all unknown and inaccessible fossils trapped under the Antarctic ice. As Pikuk said, it contains a paleontological record of what was once a truly alien medium.

[Journal of Vertebrate Paleontology]

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