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Plesiosaurs

Plesiosauria
Temporal range: Late Triassic - Late Cretaceous, 203.6–66.0 Ma
Paleo Hall at HMNS plesiosaur.jpg
Restored skeleton of Plesiosaurus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Sauropterygia
Clade: Pistosauria
Order: Plesiosauria
de Blainville, 1835
Suborders

Plesiosauroidea
Pliosauroidea


Plesiosauroidea
Pliosauroidea

The Plesiosauria (/ˌplsiəˈsɔːriə, -zi-/;Greek: πλησίος, plesios, meaning "near to" and Sauria) or plesiosaurs are an order or clade of Mesozoic marine reptiles (marine Sauropsida), belonging to the Sauropterygia.

Plesiosaurs first appeared in the latest Triassic Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution.

Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymous Plesiosaurus, was named in 1821. Since then, more than a hundred valid species have been described. In the early twenty-first century, the number of discoveries has increased, leading to an improved understanding of their anatomy, relationships and way of life.


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Wikipedia

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