Ichthyosaurs were predatory marine reptiles that swam the world's oceans while dinosaurs walked the land. They appeared in the Triassic period, dying out around 25 million years before the extinction event that wiped out the dinosaurs. Ichthyosaurs (literally 'fish-lizards') evolved from an as yet unidentified land reptile that moved back into the water. These huge animals rapidly diversified from being lizards with fins to developing a much more streamlined, fish-like form built for speed. One species has been calculated to have a cruising speed of 36 km/h. These enormous predators remained at the top of the food chain until they were replaced by the plesiosaurs.
Scientific name: Ichthyosauria
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Additional data source: Animal Diversity Web
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