Rhomaleosaurid

Rhomaleosauridae Temporal range: 201–161 Ma PreЄ Є O S D C P T J K Pg N
Rhomaleosaurus cramptoni, Natural History Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Order:	†Plesiosauria
Clade:	†Neoplesiosauria
Family:	†Rhomaleosauridae Kuhn, 1961
Genera
? †Anningasaura †Archaeonectrus †Atychodracon †Avalonnectes ? †Bishanopliosaurus †Borealonectes †Eurycleidus †Maresaurus †Meyerasaurus †Rhomaleosaurus †Sthenarosaurus ? †Stratesaurus ? †Yuzhoupliosaurus

Rhomaleosauridae is a family of pliosauroid plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many specifically from lower Blue Lias deposits that date back to the earliest Jurassic, just at the boundary with the Triassic. In fact, to date only two undisputed rhomaleosaurid low life Europe - the closely related Borealonectes russelli and Maresaurus coccai from Canada and Argentina, respectively. These two species are also the only Middle Jurassic representatives of the family. Rhomaleosauridae was formally named by Kuhn in 1961, originally proposed to include Rhomaleosaurus cramptoni and its relatives, which have short necks and large heads relatively to plesiosauroids like Elasmosaurus and Plesiosaurus, but longer necks and smaller heads relatively to advanced pliosaurids like Pliosaurus and Kronosaurus.