‘Antarctic king’ reptile discovery sheds light on weird prehistoric South Pole

31 Jan 2019

Illustration of Antarctanax shackletoni (foreground) sneaking up on an early titanopetran insect. Image: Adrienne Stroup/Field Museum

Palaeontologists have uncovered the fossilised remains of an iguana-sized reptile that roamed the once-warm continent of Antarctica.

While now we see it as the vast, icy continent where only a few brave scientists inhabit, Antarctica 250m years ago looked a lot different. At that time, it was covered in forests and rivers, and temperatures rarely fell below freezing.

It was also teeming with various types of wildlife, including a newly discovered reptile species that served as an early relative of the dinosaurs and crocodiles, and which researchers have dubbed ‘Antarctic king’. Publishing its findings in the Journal of Vertebrate Paleontology, a South African and US team revealed details of the iguana-sized creature that fell under the archosaur branch.

While the fossil skeleton is incomplete, the team was still able to create a good picture of Antarctanax shackletoni – named after polar explorer Ernest Shackleton – based on its similarities to other fossil animals. The team surmised that the creature would have been a carnivore that hunted bugs, early mammal relatives and amphibians.

A slab of brown stone containing the creature's fossilised skeleton.

A slab containing fossils of Antarctanax. Image: Brandon Peecook/Field Museum

Weird Antarctica

However, the most interesting aspect about the Antarctic king is where it lived and when, according to the researchers.

“The more we find out about prehistoric Antarctica, the weirder it is,” said Brandon Peecook, a Field Museum researcher and lead author of the paper. “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.”

2m years prior to the existence of the Antarctic king, Earth underwent its biggest ever mass-extinction event, with a series of volcanic eruptions resulting in almost 90pc of all life on Earth being wiped out. The resulting evolutionary free-for-all that followed saw archosaurs, including dinosaurs, flourish and take over the Earth.

“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 palaeontologists call ‘dead clades walking’. You’ve got tomorrow’s animals and yesterday’s animals, cohabiting in a cool place.”

He added that the discovery is just the beginning of what could be a whole treasure trove of palaeontological finds beneath the icy surface.

“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,” he said. “Antarctanax is our little part of discovering the history of Antarctica.”

Colm Gorey was a senior journalist with Silicon Republic