Named Breugnathair elgolensis, meaning 'false snake of Elgol', the creature lived about 167 million years ago.
The reptile possessed snake-like jaws and recurved teeth, yet maintained the limbs and proportions of a lizard.
This fossil is among the oldest and most complete Jurassic lizards known, suggesting it could be an ancestor to all lizards and snakes.
Lead author Dr Roger Benson noted that its unique features might indicate snake ancestors were different from expectations or evolved early predatory habits.