Plesiosauriawhile

Plesiosauria is an extinct order of marine reptiles that lived during the Mesozoic Era. These long-necked creatures were characterized by their broad bodies, small heads, and four large flippers, which they used for propulsion. Plesiosaurs are believed to have been carnivores, feeding on fish and other marine life. They are known from a wide geographic distribution, with fossils found on every continent.

The fossil record of plesiosaurs spans from the Late Triassic period, around 200 million years ago, to the end of the Cretaceous period, approximately 66 million years ago. They coexisted with other marine reptiles like ichthyosaurs and mosasaurs. Plesiosaurs are divided into two main suborders: Plesiosauroidea, which includes the well-known long-necked forms like Plesiosaurus and Elasmosaurus, and Pliosauroidea, characterized by shorter necks and larger heads, such as Liopleurodon and Pliosaurus.

The exact appearance and lifestyle of plesiosaurs are still subjects of scientific debate. While some reconstructions depict them as slow-moving creatures, others suggest they were more agile swimmers. Their extinction, like that of the non-avian dinosaurs, is generally attributed to the asteroid impact event at the end of the Cretaceous period. The study of plesiosaur fossils continues to provide insights into the ancient marine ecosystems and the evolution of marine life.