Fossil group

Rudists (Hippurites)

Molluscs · Jurassic – Cretaceous

Extinct, often bizarrely-shaped reef-building bivalves in which one valve grew into a tall cone or coil and the other formed a lid. They built reefs in warm Cretaceous seas — the role corals hold today — before dying out at the end of the Cretaceous.

A broad fossil group rather than a single taxon — the units below record it among their fauna or flora.