Fossilised ichthyosaur skull. Close-up of the eye- socket of an Opthalmosaurus sp. marine reptile from the late Jurassic period (165 to 150 million years ago). It belonged to the ichthyosaur group, which were similar to dolphins with long streamlined bodies, long snouts and powerful tails. They also had massive eyes. The bony plates seen within the eye socket are thought to have prevented water pressure from distorting the eye, allowing them to hunt squid and fish at great depths. Ichthyosaurs were viviparous (gave birth to live young). Fossil found in Oxford clay in Peterborough, UK.