Muraenosaurus was a genus of medium-sized sauropterygian plesiosaur that belonged to the family of Cryptoclididae.


Muraenosaurus reached around 6 meters (20 feet) in total body length. They lived during the Middle Jurassic Period in the seas that covered modern day Europe. Fossil specimens have been found in England and France.

This compression is represented in the aspect ratio of Muraenosaur limbs. The aspect ratio of the hind limbs is much greater than that of the fore limbs, representing a longer and more slender form. The high aspect ratio in the forelimbs may have been used for increasing maneuverability at some cost to the animal's endurance.