Plesiosaurus is a medium sized member of the plesiosauridae. Compared with other genera, Plesiosaurus has a narrow and short head. It retains a distinctive curvature on the humerus, a feature found in many ancestors of the plesiosauridae such as pistosaurs and nothosaurs. This indicates that Plesiosaurus was a primitive member of its family. Many old reconstructions show plesiosaurs with long, flexible necks arching out of the water and held in poses similar to some sauropods. However given the rigid structure of their necks, this seems very unlikely. Also recently disproved was the theory that these creatures would haul themselves onto land, similar to modern seals. Due to the structure of their skeletons, they could not survive on land and instead they were purely aquatic animals which gave birth to live young. With its sleek body and powerful fins, Plesiosaurus was an ocean going hunter, feeding on fish and ancient cephalopods which were abundant in the Jurassic waters.
Plesiosaurus was an early discovery, with its remains being found along the Jurassic Coast in southern England by collector Mary Anning in 1823. Its name means 'near lizard' due to it looking more like modern reptiles than Ichthyosaurus. Like many Mesozoica genera named in Victorian times, Plesiosaurus became a wastebasket genus, with many plesiosauridae genera being assigned to it with little study. These were later moved to their own separate genera, including Attenborosaurus.
Plesiosaurus remains have been found in the Charmouth Mudstone Formation. This is a part of the Lias lithostratigraphic unit found across a large area of northern Europe including the British Isles and Germany and spans from the latest Permian to the Early Jurassic. Other marine animals found here include Attenborosaurus, Ichthyosaurus, Archaeonectrus and various ammonites and fish. Inland lived the pterosaur Dimorphodon and the primitive thyreophoran Scelidosaurus.
Behind the scenes
- Plesiosaurus on Wikipedia