Nothosaurus ("False Reptile") was a primitive marine reptile from the Triassic Period. Despite being mainly aquatic, it would often climb onto land to rest or lay its eggs. It was an ancestor of the plesiosaurs of the Jurassic and Cretaceous.
Nothosaurus was a medium-sized marine reptile, about some 10-12 feet long length. They lived and hunted in pairs in shallow water and had a mouth full of teeth like razors – interlocking – the perfect fish trap and Nothosaurs could certainly move fast enough to catch fish in their territory. They could close those jaws with tremendous force, but the muscles that opened them, they were really weak. Nothosaurs, like all sea reptiles, need to go up to the surface to breathe.