The Plesiosaur was a marine reptile that lived during the Mesozoic era, approximately between 201 and 66 million years ago. They belong to the group of sauropterygians, characterized by large bodies, small heads, long and flexible necks, limbs transformed into flippers, and a short tail. These reptiles were well adapted for aquatic life and probably fed on fish and other marine animals.

Plesiosaur fossils are found on all continents, indicating a wide global distribution during their time of existence. They are notable for their unique appearance, with long necks that varied from shorter to more elongated forms, depending on the species. It is believed that they moved gracefully in ocean waters, using their flippers to propel themselves.