PBS Eons has a video about the rise of the Ichthyosaurs after the "Great Dying" at the end of the Permian. PBS Eons is a great, educational series from PBS on Youtube, with a new episode each week.
The marine reptiles Ichthyosaurs arose after The Great Dying, which wiped out at least 90 percent of life in the oceans, changing the seas forever and triggering a new evolutionary arms race between predator and prey.
