Only three genera survived the end-Jurassic extinction event: "Caypullisaurus", "Maiaspondylus", and "Platypterygius". They did, however, have a worldwide distribution. The last to survive was "Platypterygius". This genus became extinct about 30 million years before the end of the Upper Cretaceous period. It happened when there was a deep ocean anoxic event, which wiped out all the animals below pelagic waters. Ichthyosaurs, being reptiles, came to the surface to breath, but the extinction event removed their prey species.