sauropterygianArticle Free Pass sauropterygian, any of the
aquatic reptiles found as fossils from the Mesozoic Era (251
million to 66 million years ago). Sauropterygians include the
nothosaurs, the pistosaurs, and the plesiosaurs, all of which
were remarkably well adapted to life in the water. The largest
of these creatures were certain plesiosaurs that attained a
length of 12 metres (40 feet). 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 Triassic Period (251 million to 200
million years ago). In these small reptiles, the body was long
and slender. 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. They clearly
retained considerable mobility on land. Plesiosaurs appeared at
the end of the Triassic and remained pr