classification

Sauropterygia > Eosauropterygia > Eusauropterygia > Pistosauroidea > Plesiosauria >

Pliosauroidea > Rhomaleosauridae

synonyms: 'Peyerus'

Distribution

Upper Weald Clay, Lower Cretaceous (Barremian) of Sussex, England.

Images

Cranium (lateral view, top left; ventral (palatal) view, top right) and vertebrae. Length of vertebral series approx. 45cm (from Andrews, 1922).

Pectoral girdle in dorsal view (left), anterior view (top right), lateral view (bottom right), right humerus (center), and ribs (left)Length of pectoral girdle approx. 40cm (from Andrews, 1922).

L. capensis (Andrews, 1911)

material

-

Distribution

Sundays River Formation, Lower Cretaceous (Valangian) of Cape Province, South Africa.

Images

Skull in dorsal, lateral and ventral (palatal) view (from Cruickshank, 1997)

Leptocleidus sp.

material

Partial vertabral column, limb bones and pectoral girdle (in two parts), on display at 'Dinosaur Isle' Museum, Isle of Wight, UK.

Distribution

Vectis formation, Isle of Wight

Images

Discussion

Leptocleidus is significant in many respects. It is important stratigraphically because Lower Cretaceous plesiosaurs are rare, thus Leptocleidus fills in some of the gaps in the fossil record. Leptocleidus is a late surviving member of the primitive family Rhomaleosauridae, retaining many primitive characters. Both species are preserved in inshore/freshwater deposits leading Cruickshank (1997) to speculate that when the large and ferocious Pliosaurids appeared during the Middle and Late Jurassic, Rhomaleosaurids were outcompeted in the open ocean and forced to exploit new niches.