Sunday , February 28 2021

Iguana-sized cousin for dinosaurs discovered in Antarctica

Imagine you are walking through a lush forest, trees stretching into the sky, shrubs that dot the landscape with the soft sound of a nearby bubbling creek.

This is Antarctica.

It is not the Antarctic that we know today, but the one that existed 250 million years ago. Now researchers have discovered an iguana-sized dinosaur cousin who once wandered the lush forest area.

To know Antarctanax Shackletoni, an archosaurus, an early relative of dinosaurs and crocodiles. Based on their fossil discoveries, researchers believe that the Antarctanax was a lizard-sized carnivore that ate insects, primitive mammals and amphibians.

The vertebrae and a humerus of Antarctanax are seen here in this well preserved specimen collected from the site. (Brandon Peecook / Museum of the Field)

While other archosaurs were found, the main author of An article published in the Journal of Vertebrate Paleontology, Brandon Peecook, said that Antarctanax is particularly special.

Approximately two million years before the appearance of the Antarctanax, Earth suffered its greatest mass extinction event. Over 90% of all animal life was eliminated.

There is little evidence to suggest that many archosaurs existed prior to mass extinction during the geologic period known as Permian. However, in the following period – the beginning of the Triassic – they thrived.

"They are really hard to find in the Permian [period]. We really have a poor record of them, "Peecook said. That's probably because they were not so common. "

After extinction, he said creatures were found in: Australia, Antarctica, South America, Africa, Europe and China. "Everywhere there is the beginning of Triassic rock, they are there. In abundance."

This new discovery – like some previous fossils found – is teaching paleontologists that Antarctica was home to a very unique life.

About 300 million years ago, there was only one supercontinent on Earth, called Pangea. About 200 million years ago, it began to fall apart.

Scientists had already thought that as life evolved and thrived in this supercontinent, fossil records would show the same animals throughout the world. But this is not quite the case.

"The prevailing thinking in literature was what you found in Antarctica is a subset of what you would find elsewhere because everything was connected," Peecook said. "But the more work we've done … there are many unique life forms in Antarctica."

Antarctic paleontology

It is not exactly typical to think of paleontology being done in what people usually regard as a frozen desert. But fossils have been found in Antarctica since the 1970s.

So where exactly does anyone look for fossils in a region known for cold and snow?

"There are only two places: on the mainland there are islands, and the rocks there are 60 million years or younger," Peecook said. "The only other place is in the middle where there is this mountain range, the Transantarctic Mountains that only appear above the ice at intervals equal to irregular peaks descending in a line."

Brandon Peecook prospecting Triassic vertebrate fossils at Coalsack Bluff, a famous site of Antarctic paleontology. (Roger Smith)

Then in December 2010 and January 2011 – summer in the southern hemisphere – Peecook and his team ventured into the region to do some digging. Helicopters had to take them to different locations. The weather was not so bad, he said, with temperatures approaching just under 0 ° C, although there were a couple of times when the temperature seemed to be -40 ° C in the cold wind. Still, it was worth it, he said.

Peecook is eager to see more paleontology work done by his peers in the region, or perhaps even return to himself. It's a unique area that begs to be explored, he said.

"It's a little more exciting than you might have expected."

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