Image: Fossil of rudist bivalve, Sphaerulites sp.
Fossil of rudist bivalve, Sphaerulites sp. France. Late Jurassic, 150 million years ago.
- Robert Jones
- © Australian Museum
Rudist bivalves were the main reef-builders in the Jurassic and Cretaceous. Modern bivalves, like oysters and clams, are still common in shallow marine areas today.