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.