Ichthyosaurs

Ichthyosaurs were marine reptiles that were plentiful in the Triassic and Jurassic periods (252-145 million years ago) but became rarer in the late Jurassic and died out during the Cretaceous period, about 66 million years ago.

The first ichthyosaurus fossil was found in 1811 by the fossil hunter Mary Anning in the cliffs near her home in Lyme Regis, Dorset, England. Since then, ichthyosaur remains have been found in many parts of the world including North and South America, Europe, Russia, India and Australia.

Ichthyosaurs (the name means “fish lizard”) looked similar to both modern sharks, which are fish, and dolphins, which are mammals. Some fossils have been found with embryos inside them, showing that they gave birth to live young, like mammals but unlike fish.

They resembled fish by waving their tails from side to side to swim. Their large ear bones suggest that they were able to pick up underwater vibrations caused by their prey.

Ichthyosaurus (a commonly found ichthyosaur) could grow up to two metres (6.6 feet) long and has been estimated to have weighed up to 90 kg (198 pounds). A less common ichthyosaur was Shastasaurus which could grow up to 20 metres (65.6 feet) long and perhaps weighed around 25 tonnes.

© John Welford