A Leg Up For Snake Evolution
A NEW study of ancient snake fossils reveal the legless serpents had hind legs during the first 70 million years of their evolution. They also show how it got its bite.
“Snakes are famously legless, but then so are many lizards,” Flinders University College of Science and Engineering researcher Dr Alessandro Palci said, adding the evolution of the snake body has captivated researchers because it represents one of the most dramatic examples of the vertebrate body’s ability to adapt. Unfortunately, the fossil record offers few clues.
A member of the international research team that performed high-resolution (CT) scanning and light microscopy of the preserved skulls of Najash, Dr Palci said what sets snakes apart is their highly mobile skull that allows them to swallow big prey.
“For a long time we have been lacking detailed information about the transition from the relatively rigid skull of a lizard to the super flexible skull of snakes,” he explained. “Najash has the most complete, three-dimensionally preserved skull of any ancient snake, and this is providing an amazing amount of new information on how the head of snakes evolved. It has some, but not all of the flexible joints found in the skull of modern snakes. Its middle ear is intermediate between that of lizards and living snakes, and unlike all living snakes it retains a well-developed cheekbone, which again is reminiscent of that of lizards.”
South Australian Museum researcher Mike Lee, also part of the study, add: “Najash shows how snakes evolved from lizards in incremental evolutionary steps, just like Darwin predicted.”
The new snake family tree reveals snakes possessed small but perfectly formed hind legs for at least 70 million years.
“These primitive snakes with little legs weren’t just a transient evolutionary stage on the way to something better,” Professor Lee said. “Rather, they had a highly successful body plan that persisted across many millions of years, and diversified into a range of terrestrial, burrowing and aquatic niches.”
The study included Fernando F. Garberoglio at Universidad Maimonides in Buenos Aires, with collaborators M.W. Caldwell at University of Alberta, Dr Alessandro Palci and Professor Mike Lee at Flinders University and South Australian Museum in Adelaide, R.O. Gomez at Universidad de Buenos Aires, R.L. Nydam at Midwestern University AZ; H.C.E. Larsson at McGill University and T.R. Simoes at Harvard University.
