Cryptocleidid

Cryptocleidid is an extinct genus of plesiosaur, a type of marine reptile that lived during the Jurassic period. These long-necked, paddle-limbed creatures are known from fossil remains found primarily in England. Cryptocleidid fossils date back to the late Jurassic, around 150 million years ago.

The genus Cryptocleidid was established by paleontologist Richard Owen in the mid-19th century. The name "Cryptocleidid" refers to its hidden clavicle, a feature of its shoulder girdle. This feature distinguished it from other closely related plesiosaurs. These animals were marine predators, likely feeding on fish and squid, which they would have caught using their sharp teeth and long necks.

Cryptocleidid possessed the characteristic body plan of plesiosaurs: a broad, flattened body, four large flippers for propulsion, and a relatively small skull at the end of a long neck. Their size varied, but many were moderately sized for plesiosaurs. The discovery of Cryptocleidid fossils has been crucial in understanding the diversity and evolution of plesiosaurs during the Mesozoic Era, providing insights into the marine ecosystems of ancient seas.