Nothosaurs are prehistoric marine reptiles that existed during the Triassic period. They were small to medium-sized creatures that lived in the seas around 240 million years ago. Other synonyms for Nothosaur include pachypleurosaur, which is a genus of extinct marine reptiles, differentiated from other nothosaurs by their wider, triangular skulls. Another synonym is Keichousaurus, which was a type of nothosaur that had elongated necks and long tails, and lived in what is now China during the Triassic period. Additionally, the genus Pistosaurus is also a synonym for nothosaur, which were highly adapted to life in water and had limbs that resembled paddles. Overall, these synonyms highlight the diverse and fascinating array of marine reptiles that once populated our planet.