Is This Leggy Creature a Snake Ancestor? Scientists Disagree

Did snakes once possess legs? If a fossil analysis published in Science magazine last week is correct, an early snake ancestor may have had four legs used not for walking, but for grasping. However, not all scientists are willing to believe that snakes might have evolved from burrowing ancestors rather than from marine ones. 

Researchers from universities in the UK and Germany argue that Tetrapodophis amplectus, a fossilized species dating back to the Early Cretaceous period 100 to 146 million years ago, belongs on the snake’s family tree. The animal had several snake-like features, like a long body, a long braincase, a short snout, scales, fangs, and a flexible jaw. Its fossil also indicates that the animal had four limbs with five digits on each. They would have been short and probably used for holding onto either prey or mates, rather than for walking. It would have looked like a long snake somehow acquired stubby T. rex arms, basically (as the artist's conception above shows). 

This supports the notion that modern-day snakes evolved from burrowing lizards, not from marine reptiles. The fossil didn’t show any aquatic adaptations, like flippers or a tail that could aid in swimming, but does show low spines on its vertebrae and a long trunk, which are typically associated with burrowing animals. 

However, it’s still pretty early to rethink our conception of snake evolution. It’s possible that the animal is not a snake, as University of Alberta paleontologist Michael Caldwell told New Scientist. Finding more fossils of burrowing snake ancestors would be necessary before scientists could fully settle the ocean versus land debate over snakes’ origins.