Elasmosaurus was a large marine reptile that lived during the Late Cretaceous period, approximately 80 million years ago. Belonging to the plesiosaur family, Elasmosaurus is renowned for its extraordinarily long neck, which could make up almost half of its total body length. Measuring up to 14 meters (46 feet) in length, Elasmosaurus had a streamlined body and four large, paddle-like flippers that allowed it to navigate the ocean waters with agility. Its neck was composed of up to 72 vertebrae, significantly more than any other known animal, which it likely used to catch fish and other small marine creatures by swiftly moving its head side to side. Unlike its shorter-necked relatives, Elasmosaurus’s neck allowed it to stealthily approach prey without disturbing the water much. It inhabited the shallow seas of what is now North America, thriving in a rich marine ecosystem.