Colymbosaurus
Colymbosaurus is a colymbosaurine (derived cryptoclidid) from the Late Jurassic of the UK and Svalbard, Norway. Two valid species are known, C. megadeirus from the UK, and C. svalbardensis from Svalbard, Norway. Benson and Bowdler (2014) revised the genus Colymbosaurus and summarised its complicated history:
“Seeley (1869) (p.97-101) listed two partial postcranial skeletons from the Kimmeridge Clay Formation of Ely…and Haddenham… in Cambridgeshire as belonging to a new species, Plesiosaurus megadeirus Seeley 1869. P.