Cryptoclidus

Cryptoclidus ( ) is a genus of plesiosaur reptile from the Middle Jurassic period of England, France, and Cuba.
Discovery.
"Cryptoclidus" was a plesiosaur whose specimens include adult and juvenile skeletons, and remains which have been found in various degrees of preservation in England, Northern France, Russia, and South America. Its name, meaning "hidden clavicles", refer to its small, practically invisible clavicles buried in its front limb girdle.
The type species was initially described as "Plesiosaurus eurymerus" by Phillips (1871). The species name "wide femur" refers to the forelimb, which was mistaken for a hindlimb at the time.
Classification.
The cladogram below follows the topology from Benson et al. (2012) analysis.
Paleobiology.
The fragile build of the head and teeth preclude any grappling with prey, and suggest a diet of small, soft-bodied animals such as squid and shoaling fish. "Cryptoclidus" may have used its long, intermeshing teeth to strain small prey from the water, or perhaps sift through sediment for buried animals.
The size and shape of the nares and nasal openings have led Brown and Cruickshank (1994) to argue that they were used to sample seawater for smells and chemical traces.
Distribution.
Fossils of "Cryptoclidus" have been found in the Oxford Clay of Cambridgeshire, England. The dubious species "Cryptoclidus beaugrandi" is known from Kimmeridgian-age deposits in Boulogne-sur-Mer, France. "Cryptoclidus vignalensis" hails from the Jagua Formation of western Cuba.