Meet the 'Antarctic king,' an unlikely fossil from 250 million years ago

© Adrienne Stroup/Field Museum   "The midnight sun over Early Triassic Antarctica." Along the banks of a river, three archosaur inhabitants of the denseVoltziaconifer forest cross paths:Antarctanax shackletonisneaks up on an early titanopetraninsect,Prolacertalazes on a log, and an enigmatic large archosaur pursues two unsuspecting dicynodonts,Lystrosaurus maccaigi

By Ashley Strickland, CNN

Wildlife in Antarctica conjures up images of penguins, seals and other animals who have adapted to survive in such a harsh, frozen environment. But researchers have made an unexpected discovery that pulls back the curtain on what life may have been like in Antarctica millions of years ago. 

Instead of miles of ice and icebergs as far as the eye can see, Antarctica was a lush land full of forests and rivers 250 million years ago. And this landscape supported a diverse set of wildlife, including reptiles. Back then, it was rare for the temperature to drop near freezing or below it.

Now, researchers have found a fossil of a previously unknown species, an iguana-sized reptile that was an early relative of the dinosaurs in Antarctica. It's been named Antarctanax shackletoni. The first name translates to "Antarctic king," and the second name is in honor of Antarctic explorer Ernest Shackleton.

The newly found species is described in a study that published Thursday in the Journal of Vertebrate Paleontology.

"This new animal was an archosaur, an early relative of crocodiles and dinosaurs," Brandon Peecook, lead study author and Field Museum researcher, said in a statement. "On its own, it just looks a little like a lizard, but evolutionarily, it's one of the first members of that big group. It tells us how dinosaurs and their closest relatives evolved and spread."

The skeleton isn't complete, but the researchers have enough to understand what it looked like, and how similar it is to other archosaurs. Because of this, the researchers believe it was a carnivorous reptile that feasted on amphibians, insects and early relatives of mammals that walked the Earth 250 million years ago.

And even though scientists are learning more about Antarctica's history, the fact that this reptile lived there was still a surprise.

"The more we find out about prehistoric Antarctica, the weirder it is," Peecook said. "We thought that Antarctic animals would be similar to the ones that were living in southern Africa, since those landmasses were joined back then. But we're finding that Antarctica's wildlife is surprisingly unique."

© Brandon Peecook/Field Museum   The fossil as it was discovered.

But this animal was very much a product of the time period in which it lived. Two million years earlier, the largest mass extinction event in Earth's known history occurred at the end of the Permian era. The Permian mass extinction event, as it's known, wiped out 90% of all life on Earth.

An evolution of animal life happened in the years after the extinction event, but some groups flourished more than others. The archosaurs, including dinosaurs, were one of those groups.

"Before the mass extinction, archosaurs were only found around the equator, but after it, they were everywhere," Peecook said. "And Antarctica had a combination of these brand-new animals and stragglers of animals that were already extinct in most places -- what paleontologists call 'dead clades walking.' You've got tomorrow's animals and yesterday's animals, cohabiting in a cool place."

This suggests that after the extinction event, Antarctica is an area of the globe where evolution occurred quickly and diversity prospered. Only future research and excavation will reveal more windows into what life was like there millions of years ago.

"The more different kinds of animals we find, the more we learn about the pattern of archosaurs taking over after the mass extinction," Peecook said. "Antarctica is one of those places on Earth, like the bottom of the sea, where we're still in the very early stages of exploration. Antarctanax is our little part of discovering the history of Antarctica."