Some experts are not convinced it’s a proto-snake, but Martill and his colleagues identified several features unique to snakes. Like snakes today, the teeth on the roughly 120-million-year-old Tetrapodophis amplectus
— translated loosely as “four-legged hugging snake” — are welded to the jaw and directed backward, and there is a single row of belly scales.
The fossil also could shed light on the debate over whether snakes evolved from marine or terrestrial reptiles. The specimen’s tiny claws and elongated phalanges would likely be used for burrowing, as opposed to paddling through water, says Martill.