"Sauropterygia ("lizard flippers") is an extinct, diverse taxon of aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic ...
[Read more]
before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify till the end of the Mesozoic. Sauropterygians are united by a radical adaptation of their pectoral girdle, adapted to support powerful flipper strokes. Some later sauropterygians, such as the pliosaurs, developed a similar mechanism in their pelvis." - (en.wikipedia.org 02.03.2020)
