Fossil skeleton of plesiosaur

Plesiosaur is a collective term for the extinct marine reptiles of the genus Plesiosaurus, belonging to the suborder Dipterygii and the order Syngnathiformes. It is a group of organisms that adapt to shallow water environments, with larger individuals and long necks, hence its name. It began to appear in the late Triassic period and spread all over the world by the Jurassic period. It became extinct by the end of the Cretaceous period. The plesiosaur had an incredibly large body and was the dominant species in the ocean, dominating the Mesozoic oceans along with ichthyosaurs. Their lifestyle is similar to that of modern sea lions, mainly living in the ocean and feeding on fish. It can be divided into long necked plesiosaurs and short necked plesiosaurs. Survived from the Jurassic to Cretaceous.