Swimming in the seas of the Mesozoic were the Ichthyosaurs. Ichthyosaurs have come to be known as "fish lizards" because they are shaped like a fish or dolphin. Ichthyosaurs were like the dolphins in many ways. They could swim quickly and effectively, using their fin for stability and the "flippers" allowed them to brake. They swam using their powerful tail fin. They also seem to have given birth to live young. In some fossils, small ichthyosaurs have been found inside their mothers. Ichthyosaurs have been found with many different stomach contents. Most ichthyosaurs ate fish and ammonites, but one species, Omphalasaurus, seems to have eaten hard shellfish. Despite their hundred-million-year life in the seas ichthyosaurs died out at the end of the Cretaceous, with the rest of the dinosaurs.

Ichthyosaurus