Sauropterygia

Bol

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Sauropterygia is a group of very successful aquatic reptiles that flourished during the Age of the Dinosaurs before they became extinct. They are 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. The earliest sauropterygians appeared about 245 million years ago at the start of the Triassic period. Early examples were small semi-aquatic lizard-like animals with long limbs, but they quickly grew to be several meters long and spread into shallow waters. The Triassic-Jurassic extinction event wiped them all out except for the plesiosaurs. During the Early Jurassic these diversified quickly into both long-necked small-headed plesiosaurs proper, and short-necked large-headed pliosaurs. Originally it was thought that plesiosaurs and pliosaurs were two distinct superfamilies that followed separate evolutionary paths. It now seems that these were simply morphotypes in that both types evolved a number of times, with some pliosaurs evolving from plesiosaur ancestors, and vice-versa.

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Pagina's: 92, Paperback, Betascript Publishers