19 November 2016
Shastasaurus pacificus is the only certain species of the genus of mid Triassic ichthyosaurs. The middle Triassic is early in ichthyosaur evolution and Shastasaurus is clearly not as advanced as the more well known Cretaceous ichthyosaurs. However, the Triassic was a pivotal time for these early ichthyosaurs that led to the later Cretaceous ichthyosaurs and Shastasaurus was major player in the evolution of this family. Lacking a dorsal fin and more slender than many later members of its family, Shastasaurus possessed a significantly different shape than the later and more familiar marine lizards.