Hanosaurus

Hanosaurus lived about 250 to 247 million years ago, during the Early Triassic period.3

It was a basal sauropterygian, meaning it was an early relative of plesiosaurs and other famous sea reptiles.2

Its body was long and slender, with short limbs, which made it an axial swimmer, it moved by wiggling its body like a fish, not by paddling with its flippers.12

Hanosaurus had thick, heavy ribs (pachyostotic ribs) that probably helped it stay underwater without floating up.1

Its pelvis was very reduced, so it likely could not walk on land and spent its whole life in the water.1

The first fossil of Hanosaurus was a skull, backbone, hips, and hind legs, but no tail or front legs were found with it.1