Californosaurus perrini ('Perrin's California lizard') was an ichthyosaur, an extinct reptile, from the Lower Hosselkus Limestone (Carnian, Late Triassic) of California. It has also been known as Shastasaurus perrini and Delphinosaurus ('dolphin lizard') perrini. It is the basal-most known true ichthyosaur (Euichthyosauria). The long-snouted head is small in comparison with the rest of the body, as in basal ichthyosaurs such as Mixosaurus and Cymbospondylus. The tail is sharply turned downwards, in common with more advanced ichthyosaurs, with a small vertical fluke. It may have had a small dorsal fin. There is a small number of pre-sacral vertebrae (45 or 50). The phalanges (digit bones) are circular and widely spaced, giving the flipper a round appearance. It was three metres long. It fed on fish and other small marine creatures. Like other ichthyosaurs it probably never ventured onto dry land, and gave birth in the water.