Hydrotherosaurus was a plesiosaur, a type of marine reptile. It was not a dinosaur, though it coexisted with many dinosaurs.

All these Hydrotherosaurus pictures were collected from the internet. Enjoy and explore:

Hydrotherosaurus was described by the following scientific paper(s):
  • S. P. Welles. 1943. Elasmosaurid plesiosaurs with description of new material from California and Colorado. Memoirs of the University of California 13:125-254