The roughly 120 million-year-old snake, dubbed Tetrapodophis amplectus (literally, four-legged snake), likely didn't use its feet for walking. Instead, the appendages may have helped Tetrapodophis hold onto a partner while mating, or even grip unruly prey, said study co-researcher David Martill, a professor of paleobiology at the University of Portsmouth in the United Kingdom.

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.