Plesiosaur tooth embedded in its original matrix. Plesiosaurs were marine reptiles that lived in seas across much of the world during the Mesozoic Era, from about 203 to 66 million years ago. They first appeared in the Late Triassic and survived through the Jurassic and Cretaceous. Their fossils have been found worldwide, including in Morocco, where ancient marine deposits have preserved remains of these remarkable reptiles. Although often grouped together, plesiosaurs came in a few different body styles. Some had very long necks and small heads, likely using quick strikes to catch fish and squid, while others had shorter necks and larger, stronger jaws better suited for grabbing bigger prey. Their diet included fish, cephalopods such as squid and ammonites, and other marine animals. They shared the oceans with ichthyosaurs, mosasaurs in the later Cretaceous, sharks, sea turtles, and countless invertebrates, while dinosaurs roamed the land above their coastal environments. With their four powerful flippers, plesiosaurs were highly specialized swimmers and remain some of the most recognizable marine reptiles of the prehistoric world.
