The largest of these creatures were certain plesiosaurs that attained a l.... million year

Characteristic of the sauropterygians are their long, flat skulls with curved, rounded teeth and complex palates; they also had long, flexible necks with up to 80 vertebrae. The first sauropterygians to appear were the nothosaurs of the (248 million to 206 million years ago). The limbs were comparable to those of terrestrial reptiles, and the animals probably moved through the water by undulating the body and paddling with the limbs. Plesiosaurs appeared at the end of the Triassic and remained prominent into the Late (99 million to 65 million years ago). Fossilized remains are most common in deposits of the (206 million to 144 million years ago) in England and Germany and of the Late Cretaceous in the United States. Formerly considered a subgroup of Sauropterygia are the of the Middle (242 million to 227 million years ago). million year