Nothosaurus was a semi-oceanic animal which probably had a lifestyle similar to that of today's seals. It was about 4 metres (13 ft), with long, webbed toes and possibly a fin on its tail. When swimming, Nothosaurus would use its tail, legs, and webbed feet to propel and steer it through the water. The skull was broad and flat, with long jaws, lined with needle teeth, it probably caught fish and other marine creatures. Nothosaurus hunted by sneaking up slowly on prey, such as shoals of small fish, then putting on a last-minute burst of speed. Trackways attributed, partly by process of elimination, to a Nothosaur, that were reported from Yunnan, China in June 2014, were interpreted as the paddle impressions left as the animals dug into soft seabed with rowing motions of their paddles, churning up hidden benthic creatures that they snapped up. Once caught, few animals would be able to shake themselves free from the mouth of Nothosaurus.
In many respects its body structure resembled that of the much later plesiosaurs, but it was not as well adapted to an aquatic environment. It is thought that one branch of the nothosaurs may have evolved into plesiosaurs such as Liopleurodon, a short-necked plesiosaur that grew up to 6.4 metres (21 ft), and the long-necked Cryptoclidus, a fish eater with a neck as long as 9 metres (30 ft).
Nothosaurus lived in warm shallow seas and rivers, so it would most likely eat animals like fish and crabs, it may also have eaten eggs, a Nothosaurus fossil was found with a Coelophysis hatchling in its stomach area implying that either Coelophysis babies were extremely careless or Nothosaurs ambushed young dinosaurs either by crawling on land or ambushing them the same way crocodiles do.
In Popular Culture
Nothosaurus was shown in the documentary Chased By Sea Monsters. They are shown first at the surface, curiously investigating Nigel, Nigel holds one like an alligator until it needs to breathe.
It appears briefly in Sea Rex where it is shown to be chasing a Mixosaurus.It also appears briefly in Sea Monsters: A Prehistoric Adventure in the timeline sequence. In the Rite of Spring segment of Disney's Fantasia, Nothosaurus is briefly depicted; feeding its young and as the anachronistic prey of Dimetrodon. This is inaccurate because Nothosaurus lived on the mid to late triassic while dimetrodon lived in the mid Permian. It also appears in Son of Kong, where the Nothosaurus that attacks Denham, Hilda and Kiko after they uncover the treasure, only to be killed by Kiko.