Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Order Plesiosauria
Suborder Plesiosauroidea
Family Plesiosauridae
Genus Plesiosaurus
1st Species Plesiosaurus dolichodeirus
Other attributes
Time Range 199.6-175.6 mya
Location United Kingdom
Name Meaning Near to reptile
Physical Dimensions 3.5 meters long
Dietary Classification Carnivore
Plesiosaurus is a plesiosaurid plesiosaurian reptile from the Early Jurassic of the United Kingdom. It was named in 1821 by William Daniel Conybeare. It was one of the first marine reptiles (nicknamed antediluvian reptiles at the time) known to science, and, like its ichthyosaur and lizard counterparts, it was a wastebasket taxon.


As earlier descriptions had told, Plesiosaurus resembled a snake stuck in a turtle's body. It had a sleek, streamlined body, 4 flippers, a short tail with a small fin on its end, a long neck, and a small head with a mouth filled with sharp, interlocking teeth. Its body would have been covered in scaly skin.


Plesiosaurus was a predator, preying on fish and cephalopods. Its sharp teeth were used to get a hold of slippery prey, and its long neck would have helped it snake into schools of fish.


Plesiosaurus had a short tail comparable in size to its large flippers; due to this, it would have propelled itself by moving all its flippers at the same time (similar to how people navigate in a rowboat), as opposed to the other marine reptiles, which propelled themselves by moving their tail from left to right. People even reconstruct it as able to crawl onto land and lay eggs on the shore like a turtle; however, it lacked the skeletal features in order to perform that task, and so, the most accepted reconstruction is a fully-aquatic reptile that gives birth to live young. As well as this, Plesiosaurus' neck was thought to be very flexible, right before being theorized to be very rigid; however, due to a study done on its semi-close relative, Elasmosaurus, it is now assumed that Plesiosaurus' neck was still somewhat flexible. In order to hunt, Plesiosaurus would swim near a school of fish and flex its neck to select an individiual before grabbing its target with its jaws.

In popular cultureEdit

Plesiosaurus was one of the 1st Mesozoic animals discovered, so it was featured in Crystal Palace Park (a pleasure ground in London), alongside Iguanodon (depicted as a horned dragon), Megalosaurus (also depicted as a dragon), Pterodactylus, Ichthyosaurus, and Mosasaurus (depicted as a giant, iguana-like squamate). Since then, it has managed to become the archetypical plesiosaur (and by extension, the archetypal Mesozoic marine reptile), and has featured in major pieces of media such as the original Journey to the Center of the Earth novel (where it fought with an Ichthyosaurus), Fantasia, and the The Lost World novel; it was even planned to be in Jurassic World before it got cut. As well as this, it even inspired the creation of a cryptid called the Loch Ness Monster; however, for the rest of its publicity, it would be overshadowed by its semi-close relative, Elasmosaurus.

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