An old snake cheek sheds light on the evolution of the modern snake skull: 1
A new study by a collaboration between the Paleontologists of Argentina and the University of Alberta adds a new piece to the puzzle about the evolution of snakes.
Researchers examined the strikingly well-preserved fossil of the last snake Najash rionegrina discovered in Argentina. The study shows that nearly 100 million years ago, these snake legs still had a cheekbone – also known as a bone from the south – that had disappeared in their modern offspring.
"Our findings support the idea that the ancestors of modern serpents were large bodies and large lips – instead of small burrowing shapes, as previously thought," explained Fernando Garberolio of Fundazion Azara at Universidad Maimunides, Buenos Aires, Argentine and Aires, Argentine lead author of the study. "The study also revealed that early snakes retained their hind limbs for a long time before the origin of modern snakes, which are largely limitless."
For decades, paleontologists' understanding of snake evolution was difficult. limited fossil record. The new fossils presented in this study are critical to reconstructing the early steps in the evolutionary history of modern snakes.
"This study revolutionizes our understanding of the bone of the south in snake and non-snake lizards," says Michael Caldwell, a professor in the Department of Biological Sciences and Earth and Atmospheric Sciences and co-author of the study. "After 160 years of error, this document corrects this very important characteristic based not on assumptions but on empirical evidence."
Nearly 100 million years of fossil snakes described in this study discovered in Northern Patagonia are closely related to ancient the breed of snakes that inhabited the continents of the southern hemisphere of Gondwana, and appear to be associated with only a small number of obscure, modern snakes. The researchers used micro-computed tomography (micro-CT) scanning to visualize the structures of the skull in the sample, examining the pathways of nerves and blood vessels, as well as the skeletal structure that would otherwise be impossible to see without being damaged the fossil.  "This study is critical to understanding the evolution of the skulls of modern and ancient serpents," Caldwell added.
The paper, "The New Skulls and Skeletons of the Cretaceous Leg of the Snake Nadzhash and the Evolution of the Modern Plan for the Snake Body," will be published in Advances in Science .
DOI: 10.1126 / sciadv.aax5833
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