The oldest known snake fossils ever discovered are described online in Nature Communications this week. The fossils push back the first record of snakes by 70 million years and challenge previous theories that suggested that the snake’s head evolved after the evolution of its elongated body.

Using a number of fossilised skull bones, Michael Caldwell and colleagues identified four new species of snakes, from England, Portugal and the USA, dating from 143 to 167 million years ago. They find that snakes originated at a time when most other major groups of scaled reptiles were rapidly diversifying and that they existed in different parts of the globe in many different habitats including swamps, ponds, rivers and coastal systems, during the Middle Jurassic.

The creatures share recognisable features with modern-day snakes, such as sharp, backward pointing teeth, but their overall shape, length and body form remains unknown. The authors suggest that the presence of key snake-like features in these early snake skull bones hints that the classic snake head evolved first and was then followed by the evolution of the elongated, limbless body.