How the turtle got its shell
A Chinese fossil shows the belly plate evolved first, and the back shell came later.
- When
- Known to
- ± 3 million years
- Era
- Triassic, Mesozoic
Odontochelys semitestacea, about 220 million years old, has a fully formed plastron covering its underside but only broadened ribs where the carapace should be — and it still has teeth. It settles a long argument about turtle origins, showing the shell was assembled in stages from the belly upwards, most likely as protection from predators attacking from below in water.