|See also ichthyosaur dinosaur Compare pterosaur any of various extinct marine reptiles of the order Sauropterygia, esp any of the suborder Plesiosauria, of Jurassic and Cretaceous times, having a long neck, short tail, and paddle-like limbs|
|[C19: from New Latin plēsiosaurus, from Greek plēsios near + sauros a lizard]|
|plesiosaur (plē'sē-ə-sôr') Pronunciation Key
Any of various large, extinct marine reptiles of the genus Plesiosaurus and related genera of the Mesozoic Era. Most plesiosaurs had a small head on a long neck and a broad body with paddlelike limbs; one group had a large head on a short neck. The exact relationship between plesiosaurs and other reptiles is not known.