Newly discovered 'four-legged' fossil sheds light on snakes' evolution

Scientist have found four-legged fossil of a snake that suggests that the slithery creatures may have evolved from burrowing ancestors.

The authors determined that the four-legged creature is in fact an ancestor of modern-day snakes.

The newly discovered species Tetrapodophis amplectus in Brazil's Crato Formation, which lived during the Early Cretaceous 146 to 100 million years ago, maintains many classic snake features, such as a short snout, long braincase, elongated body, scales, fanged teeth and a flexible jaw to swallow large prey. It also maintains the typical vertebrae structure seen in modern-day snakes that allows for the extreme flexibility required to constrict prey.

The main, glaring difference is Tetrapodophis's four limbs, which do not appear to have been used for locomotion. Rather, the shorter exterior digits and lengthened second digit suggest that the limbs were used for grasping, either to seize prey or to clasp during mating, the authors said.

It was also noted that the specimen lacked the long, laterally compressed tail typically found in aquatic animals, further suggesting that snakes did not evolve from marine ancestors.

The findings are published in the journal Science.