Short-necked plesiosaurs were marine reptiles that lived during the Mesozoic Era, primarily in the late Jurassic and early Cretaceous periods. Unlike their long-necked relatives, these creatures had relatively short necks and large bodies, which made them well-suited for hunting in the ocean. They had four flippers that helped them swim efficiently through the water. These animals belonged to the group known as Plesiosauria, which included various species with different body shapes and sizes. Short-necked plesiosaurs, such as Elasmosaurus, were known for their powerful jaws and sharp teeth, allowing them to catch fish and other marine prey effectively.