Sauropterygia ("lizard flippers")'s a group of very successful aquatic reptiles that flourished during the Age of the Dinosaurs before they became extinct. They're united by a radical adaptation of their shoulder, designed to support powerful flipper strokes. Some later sauropterygians like the pliosaurs developed a similar mechanism in their pelvis. Origins and evolution The earliest sauropterygians appeared about 245 million years ago (Ma), at the start of the Triassic period. Early examples… (More on Sauropterygia)