The shastasaurs were an early group of ichthyosaurs, living 230-210 million years ago, in the Triassic period. They had big heads with a long snout. They had reduced or no dorsal fins. Shastasaurs were the largest of all ichthyosaurs.
One species of the Western American shastasaurid, Shonisaurus, grew to 23 m long. Shastasaurs ate fish and other small aquatic animals, like ammonites. This group included the genera Shonisaurus, and Shastasaurus.