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A rare fossil trio reptile discovered in Antarctica

View author Antarcticax shackleton (left). On the other side of the stream, the big arhosaur devours dikinodon no doubt.
Image: Adrienne Stroup, a field museum

Fossilized remains of an early reptile dating to roughly 250 million years have been discovered in incredible places: Antarctica. The discovery shows how wild animals recovered after the worst mass extinction in the history of our planet and how Antarctica once hosted ecosystems unlike any other.

It is unnecessary to say that paleontological work in Antarctica is very different from elsewhere. Unlike Alberta or Montana, for example, where abundant rocks are found, the Antarctic is covered with a massive ice layer, harnessing most of its paleontological history. And it's not like Antarctica has stories to apologize – it really is. Just recently, in the last 30 to 35 million years, the continent has fallen. Before that, there was a warm climate, lush forests, rushing rivers and an abundant wealth of life.

In order to find the fossilized traces of that forgotten life, whether it is Antarctica or elsewhere, scientists need to find rocks. Antarctica offers only two possibilities: the islands along its coastline and the central transantarctic mountain – the spine of the mountains that cut the cracks in the mid-continent. The summits of these mountains go through the glaciers, creating a rocky archipelago – and a place where paleontologists can do some exploratory works. Here, on the Fremouw's formation of the Trans-Ancient Mountains, Brandon Peecook, a paleontologist from the Natural History Museum and the main author of a new study, discovered a rare Thracian reptile.

"Standing on the mountain, it was hard to imagine how it really looked like an extraterrestrial Antarctica," Peecook said to Gizmoda. "Looking around, I did not see any traces of macroscopic life for miles in every direction."

Brandon Peecook explores Antarctica.
Image: Roger Smith

Indeed, today the Antarctic can be devastated and unsustainable, but it has not always been the case. Hundreds of millions of years ago, Formation Fremouw was the home of vibrant life-filled forests, from winged insects to quadrilateral reptile herbivores. Discovery of an unknown iguana reptile named Antarctanax shackleton, now contributes to our knowledge of the former ecological glory of the continent.

Antarctanax means "king of Antarctica" and Shackleton is top of the hat for British polar researcher Ernest Shackleton. A. shackletoni was an archosaur, sharing a common ancestor with dinosaurs and crocodiles who lived during the early Triassic period about 250 million years ago. He is now one of the earliest lizards that appears in fossil recordings. Details of this discovery were published today in Journal of Vertebrate Paleontology.

The partial fossil consists of perfectly preserved vertebrae (including neck and back), partial skull, two legs, several ribs, and upper arm bones. It was discovered during the expedition to the Fremouw formation during the Antarctic Summer 2010-2011. The analysis of these fossilized bones (especially skulls) and fossils found beside it suggests that it is a meso size of the surface, chewing gum, amphibians and early proto-mammals. Roger Smith from Witwatersrand University in South Africa and Christian Sidor from the University of Washington in Seattle helped Peecook to analyze.

Side of the fossil, showing the spine and spine.
Image: Brandon Peecook, Field Museum

Early Trio is of great interest to paleontologists because it came in the light of one of the worst episodes in Earth's history – the ultimate massive mass extinction, when extreme and long-lasting volcanism destroyed nearly 90 percent of our planet's life. This resulted in a comprehensive ecological restart, which led the survivors to take over power. Among those survivors were archaicists who took full advantage of them.

"The pattern that is repeatedly repeated with massive disturbances such as ultimate massive extinction is that some animals that survived quickly filled up empty spaces," Peecook said. "Arhosaurs are a great example – a group of animals that were able to do virtually everything. This log is totally ballistic.

The opposite side of the fossil, shows a few vertebrae, ribs and right foot.
Image: Brandon Peecook, Field Museum

Indeed, arhosaurs, including dinosaurs, were among the greatest users of this recovery, experiencing tremendous growth and diversity. Prior to the mass extinction, these creatures were limited to equatorial areas, but thereafter they were "everywhere," according to Peecook – including, as we now know, Antarctica. The continent was home A. shackletoni some 10 million years before the emergence of real dinosaurs. On the sidelines, Antarctica hosted a dinosaur, but not until the Jurong Period.

This discovery also throws light on the particular Antarctic animals. Since Antarctica and South Africa were physically connected at that time, paleontologists worked on the assumption that the two regions have a lot in common in the sense of local game. Since fossils abounded in South Africa, paleontologists used this record to figure out the way of life that probably existed in Antarctica. But, as Peecook explained, it turns out to be a mistake; Antarctica has hosted ecology unlike any other.

"We know the fossil record of South Africa very well, but in Antarctica we have only discovered about 200 species," he said. – But we do not find these kinds anywhere else. Paleontologists only went to Antarctica several times, but every time they went to find new species and surprising new phenomena – it's really exciting. The original argument that you could link these two environments is now incorrect. Antarctic records have many unique things that are happening. "

This Antarctica contained a unique set of species, which is not surprising. As it is today, the continent was at a great altitude, with long summer days and extended nights in winter. Animals and plants had to adapt to survive, adopting new physical characteristics and survival strategies.

The mind creeps into the thought of all the unknown and unavailable fossils trapped under Antarctic ice. As Peecook said, he has a paleontological record of a former extraterrestrial environment.

[Journal of Vertebrate Paleontology]

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