Scientists have discovered a new species of lizard that lived in Southern Brazil over 80 million years ago and could help solve an evolutionary mystery.
The discovery of this "Old World" lizard from the "New World" may reshape what we know about the evolutionary history of reptiles alive today, the University of Albertza reported.
"The roughly 1,700 species of iguanas are almost without exception restricted to the New World, primarily the Southern United States down to the tip of South America," said Michael Caldwell, biological sciences professor from the University of Alberta and one of the study's authors.
Despite these geographical restrictions, iguanas' closest relatives are chameleons and bearded dragons, which come from the Old World. The discovery of the ancient lizard species, dubbed Gueragama sulamericana, could help solve some of explain how this came to be. Gueragama sulamericana is the first acrodontan iguanian (a species that has teeth fused to the top of its jaw) to be discovered in South America, suggesting acrodontan iguanians of the Old World and non-acrodontans in the New World went through a "worldwide distribution" before the break up of Pangaea.
"This fossil is an 80 million year old specimen of an acrodontan in the New World," Caldwell said. "It's a missing link in the sense of the paleobiogeography and possibly the origins of the group, so it's pretty good evidence to suggest that back in the lower part of the Cretaceous, the southern part of Pangaea was still a kind of single continental chunk."
Scientists can gain insight into the landscape and ancestry of Pangaea when it was a whole landmass by looking at the distribution of plant and animal fossils. The discovery of this new lizard species suggests the evolutionary group is relatively old and Southern Pangaean in origin. The scientists believe that after the Pangaean break up, the acrodontans and chameleon groups ruled the Old World while the iguanid group was left alone in South America.
"South America remained isolated until about 5 million years ago. That's when it bumps into North America, and we see this exchange of organism north and south. It was kind of like a floating Noah's Arc for a very long time, about 100 million years. This is an Old World lizard in the new world at a time when we weren't expecting to find it. It answers a few questions about iguanid lizards and their origin," Caldwell said.
The findings were published in a recent edition of the journal Nature Communications.