The findings produced by researchers from museums and universities in Belgium and the UK, such as Southampton University, contradict previous theories that the reptiles were the last survivors from the Cretaceous period (the time span between 145 and 66 million years ago).
Research has shown that the ichthyosaurs appeared during the Triassic and Jurassic period and survived into the Cretaceous which suggests the end of the Jurassic extinction did not occur for the species.
The fact they survived the Jurassic period makes their fossil record unique from other marine reptile groups.
One of the most spectacular fossils ever found on Dorset's Jurassic Coast has inspired one of this summer's Olympic arts projects. The sea creature, known as a Pliosaur, would have been as big as a bus. Now a model's been made with a cinema inside to teach people about the coastline.