The family of Spinoasurids contains such genera as Spinosaurus and Siamosaurus. They were two-legged, meat-eating dinosaurs of large size and shared the common feature of long crocodile-like jaws with long straight non-serrated teeth. This adaptaion may have been suited for spearing and eating mainly fish. They may have been semiaquatic, both living and hunting on land and in water.

The Spinosaurus had a large sail of bone and skin on its back similar to that of the Dimetrodon. The purpose of which is not known. The first Spinosaurus was discovered in Eygpt by the fossil hunter Ernst Stromer in 1912. The remains were destroyed during World War II.