Antarctanax shackletoni traces insects on the banks of the Antarctic River during the Early Triassic.
Copyright: Adrian Stroup / Field Museum
Millions of years before the earth trembled under their feet T rex – The "King of the Dinosaurs" – the wooded Antarctic was the home of the king of the iguana size lizard.
This ancient reptile was archosaurus – part of the same group that later included dinosaurs, pterosaurs and crocodiles. Scientists have recently discovered a partial skeleton of the lizard 250 million years ago, when Antarctica burst with plant and animal life.
Not only that the former king's fossils provide a sharper image of the forest landscape in the ancient past of Antarctica but also help explain the evolutionary landscape after the greatest mass extinction in Earth's history, scientists said in a new study. [Antarctica: The Ice-Covered Bottom of the World (Photos)]
Although the fossil lizard was incomplete, researchers were able to tell from molten vertebrae that the animal is an adult reptile, and it probably measures about 4 to 5 feet (1.2 to 1.5 meters) in length. They called it Antarctanax shackletoni: The first part of the name comes from the Greek words "King of Antarctica". the second part is the nod of the pioneering British polar explorer Ernest Shackleton, who named Beardmore Glacier – where many Antarctic fossils, including Antarctanax, were recently found – after the expedition in 1908.
Fine features in the bones of the spine and the lizard indicate that it is a new species and its leg shape suggests that it lives on the ground and crosses the forest floor, lead study by Brandon Peecook, postsecondary physician Meeker on the Chicago Natural History Museum playground said living science.
"He has no legs to make us think he lives in a tree, or he's a watchman," Peecook said.
These trees can be hard to imagine if you think Antarctica is today: frozen, mostly lifeless, an icy desert. Hundreds of millions of years ago, Antarctica hosted a warm, humid environment where temperatures rarely – though sometimes – dipped under freezing, the authors of the study said.
"We have evidence of extensive forests all over the place and the great rivers that pass through these forests," Peecook said. Roaming between trees and rivers were amphibians, mammalian relatives called cynodonti, other mammals similar to predators called dicynodonti who had tusks and beaks and reptiles as Antarctanax, he added.
But this fossil also contributes to an important developmental story. With the discovery of this unknown ancient reptile, scientists associate the unexpected archosaural diversity that arose shortly after the mass destruction of the Perms – a catastrophic event about 252 million years ago that destroyed about 96 percent of all marine species and about 70 percent of the land vertebrates. Scientists previously thought that after this global extinction event it took millions of years for animals to diversify and fill the empty niches of the planet. But Antarctanax shows that archosaurus began to diversify several million years after the death of Permian, according to a study.
"If you look at the earliest Triassic rocks, archosaurus and other groups are emitting explosives," Peecook told the scientists. While Antarctanaxit is likely that the Yu-jan-like body does not seem to be particularly dramatic, some reptile triasters evolved to climb across the sky like pterosaurs, while others returned to the sea and eventually evolved into giant ihthyosaurs and plesiosaurs-and their ancestors probably emerged at the same time Antarctanax, he explained.
"Existence Antarctanax in early Triassic suggests that all these other crazy lines must already exist at this point, even if we do not have a good fossil record, "Peecook said.
The findings were published today (January 31) in the Journal of Paleontology of Vertebrates.
Originally published on Live science.