marine reptiles (reptile) found as fossils from the Triassic Period (251 million to 200 million years ago) in southwestern and eastern Asia, North Africa, and especially Europe.

Nothosaurus was characterized by a slender body, long neck and tail, and long limbs. Although the animal was aquatic, the limbs were less specialized for swimming than they were in more advanced sauropterygians (sauropterygian) such as pistosaurs, pliosaurids, and plesiosaurids (plesiosaur). The palate in the nothosaurs was closed, the air passages being separated from the food passages—an adaptation that aided feeding while in the water. The skull was long and flat with large openings. Numerous pointed teeth were present along the margins of the jaws. Nothosaurus moved through the water by undulating its body and by swimming with its limbs. As did the other sauropterygians, Nothosaurus evolved from terrestrial reptiles distantly related to lizards (lizard) and snakes (snake).