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Rare fossils of triassic reptiles discovered in Antarctica

Artistic representations Antarctanax shackleton (left, go). Through the brook, the great Archosaurus slammed off a few unsuspecting dicynodons.
Image: Adrienne Stroup, Field Museum

Petrified remains of early reptiles, dating back about 250 million years, were uncovered in the most dangerous places: Antarctica. The discovery shows how the wildlife recovered from the worst mass extinction in the history of our planet and how Antarctica once hosted the ecosystem unlike others.

Needless to say, paleontological work in Antarctica is very different than elsewhere. Unlike Alberta or Montana, for example, which represent rich rock outcrops, Antarctica is covered with a massive sheet of ice, obscuring much of its paleontological history. And it's not as if Antarctica had no stories to tell – it's very important. Only recently, during the last 30 to 35 million years, the continent has frozen. Previously, it was home to a warm climate, lush forests, hurrying rivers and a remarkable amount of life.

To find fossilized traces of this forgotten life, whether it be Antarctica or elsewhere, scientists need to find stones. Antarctica provides only two options: islands along the coast and central Transantarctic Mountains – the ridge of the mountain, which cuts the intersection in the middle of the continent. The peaks of these mountains go through the glaciers, creating a rock archipelago – and a site for paleontologists to do some research. There is, at Fremouw's formation of the Transantarctic Mountain, that Brandon Peecook, a paleontologist with Field Natural History Museum and the lead author of a new study, discovered a rare triassic reptile.

"He stood on the mountain, it was hard to imagine how Antarctic extraterrestrials had to look like they were at that time," Peecook told Gizmod. "When I looked around, I did not see the traces of macroscopic life a mile in every direction."

Brandon Peecook is looking for Antarctica.
Picture: Roger Smith

Antarctica can be sad and inhospitable today, but it has not always been so. Hundreds of millions of years ago, the Fremouw formation was home to a lively, full-lived forest, from winged insects to four-legged creeping herbivores. The discovery of a previously unknown reptile of iguanas, dubbed Antarctanax shackletoni, now complements our knowledge of the former ecological fame of the continent.

Antarctanax means "King of Antarctica" and shackletoni is the tip of a hat to British polar explorer Ernest Shackleton. A. shackletoni was an archosaur who shared a common ancestor with dinosaurs and crocodiles, and lives in the early triassy about 250 million years ago. It is one of the oldest lizards to appear in fossil recordings. Details of this discovery were published today in the Journal of Paleontology on Vertebrates.

The partial fossils consist of perfectly preserved vertebrae (including the neck and back), partial skulls, two legs, some ribs and upper shoulder bone. It was discovered during an expedition to the Fremouw formation during the 2010/2011 summer season in Antarctica. The analysis of these fossilized bones (especially the skulls) and the fossils found alongside it suggests that they are beer of large size carnivores that behave on insects, amphibians and early proto-mammals. Roger Smith of Witwatersrand University in South Africa and Christian Sidor of Washington University in Seattle helped Peecook with analysis.

Fossil side showing the vertebrae and shoulder bone.
Image: Brandon Peecook, Field Museum

The early triassic is of great interest to paleontologists because it came as a result of one of the worst episodes of Earth's history – the ultimate Perm mass extinction, when extreme and prolonged volcanism destroyed nearly 90 percent of our planet's life. The result was an extensive ecological restart that set the survival conditions for survivors. Among these survivors were archosaurus who took full advantage.

"The pattern we see over and over with massive disorders such as the Permanent Permaan Extinction is that some of the animals that survived quickly filled empty ecosystems," Peecook told Gizmod. "The Archosaurus is a great example – a group of animals that could practically do everything, this ball was completely ballistic."

On the opposite side of the fossils, showing several vertebrae, ribs and right legs.
Image: Brandon Peecook, Field Museum

Archosaurs, including dinosaurs, were among the largest recipients of this recovery period, experiencing tremendous growth and diversity. Before the mass extinction, these creatures were limited to the equatorial areas, but then they were "everywhere," according to Peecook – including, as we now know, Antarctica. The continent was at home A. shackletoni about 10 million years before the appearance of true dinosaurs. As a side, Antarctica hosted dinosaurs, but not until the Jurassic period.

This discovery also illuminates distinguishing Antarctic animals. Given that Antarctica and South Africa were physically interconnected at that time, paleontologists worked on the assumption that both regions have much in common with local wildlife. And because the fossils are rich in South Africa, paleontologists used this record to draw conclusions about what kind of life existed in Antarctica. But, as Peecook explained, it is a mistake; Antarctica hosted ecology, unlike others.

"We know the fossil record in South Africa really well, but we found only about 200 species in Antarctica," he said. Paleontologists have gone to Antarctica several times, but each time they go, they find new species and surprise new events-it's really exciting. <br /> <br /> The original argument that you could unite these two environments together is now wrong. the record has a lot of unique things. "

The fact that Antarctica was a unique set of species is not surprising. Just as today was the continent at high altitude, it was characterized by prolonged days in the summer and prolonged nights in the winter. Animals and plants have had to adapt to survive, and thus adopt new physical properties and survival strategies.

The mind grows to think of all unknown and unreachable fossils trapped under the Antarctic glacier. Like Peecook, he holds a paleontological record of what was once a truly foreign environment.

[Journal of Vertebrate Paleontology]

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