Livescience has a story about the oldest snake fossil.  It doesn’t look too different from a modern snake, except…  it has four legs!  Named Tetrapodophis amplectus (literally, four-legged snake), it lived about 120 million years ago in what is now Brazil.  The fossil was discovered in an exhibit of specimens from the Crato Formation by David Martill, a professor of paleobiology at the University of Portsmouth in the United Kingdom. 

The original paper appeared in the jounal Science.

Previous research has detailed two-legged snake fossils, but this is the first known snake ancestor to sport four legs, he said. It likely evolved from terrestrial-burrowing creatures, and was a transitional animal that lived during the shift from ancient lizards to modern-day snakes, he added.

“We’ve found the ancestor of all snakes,” Martill told Live Science. “We have found the missing link between four-legged lizards and snakes.”

Martill happened upon the fossil during a field trip with his students to the Solnhofen Museum (formerly known as the Bürgermeister-Müller-Museum) in Germany. As they were looking at an exhibit of fossils from the Crato Formation, in northeastern Brazil, Martill noticed the 7.8-inch-long (20 centimeters) snake. It had a plaque that said “Unknown fossil.”

“My jaw just dropped,” he said. “I thought, ‘Bloody hell, that’s a fossil snake.’”

The Crato Formation happens to be one of Martill’s prime subjects. He is the author of “The Crato Fossil Beds of Brazil: Window into an Ancient World” (Cambridge University Press, 2008), so he knew that a snake from the Crato Formation would be “about 20 million years older than any other fossil snake,” he said.

Intrigued, he leaned in closer to the display to get a better look.

“I thought, ‘Bloody hell, it’s got back legs!’” Martill said. “It had front legs. Nobody had ever seen a snake before with four legs, and yet evolutionary theory predicts that there should be an animal that is transitional between four-legged lizards and snakes, and here it was.”