It has long been thought that snakes evolved from lizards but concrete evidence has not been found to prove it, until now. Scientists have, for the first time, found a fossil of a snake with 4 legs.
The snake, named Tetrapodophis amplectus, has 4 tiny legs just a few millimetres in length and a head the size of a fingernail. The total length of the snake is 20 centimetres so it was a fairly small animal. It has fully formed arm and leg bones complete with elbows.
According to scientists, Tetrapodophis shows adaptations for burrowing rather than swimming, this suggests that snakes evolved from terrestrial lizards rather than marine ones.
In the past scientists have found snakes containing pelvises and hind limb buds, which suggested they were once four legged but this is the first time a snake fossil with actual legs has been found.
The size of the legs suggests that this snake is closely related to modern day snakes. Proportionally, lizards have much larger legs than Tetrapodophis so this suggests this snake was probably just a few evolutionary steps away from losing its legs.
Dr. Dave Martill, who found the fossil in a collection in a German Museum, says as snakes began to slither, they stopped using their legs to walk and probably started to use them for grasping prey or in mating. Eventually it became more advantageous to lose them all together.
Martill says the arms and legs in the snake were highly specialized with claws on the end. This is evidence that these arms did an have an important function for the snake, they were not vestiges.
Amazingly this fossil has been sitting in a German museum for decades labeled as an unknown fossil. When Dr. Martill saw it, he was extremely surprised to see it and immediately asked the museum if he could study it.
The snakes’ last meal can also be seen in the fossil. It is likely it was a salamander.