Nothosaurus ('false lizard', from the Ancient Greek νόθος, nothos, 'illegitimate' and σαῦρος, sauros, 'lizard') is an extinct genus of sauropterygian reptile from the Triassic period, approximately 245–228 million years ago, with fossils being distributed throughout the former Tethys Ocean, from North Africa and Europe to China. It is the best known member of the nothosaur order.