Nothosaurus was a semi-
oceanic animal which most likely had a lifestyle similar to that of today's
seals. It was about , with long, webbed toes and possibly a fin on its tail. However, some species such as
N. zhangi and
N. giganteus were larger, up to . 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. Trackways attributed, partly by process of elimination, to a nothosaur that was 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
pliosaurs such as
Liopleurodon, a short-necked plesiosaur that grew up to , and the long-necked
Cryptoclidus, a fish eater with a neck as long as . ==Species==