Leptocleidus Andrews, 1922
Leptocleidus is stratigraphically important because Lower Cretaceous plesiosaurs are rare and so Leptocleidus fills in a gap in the fossil record. Leptocleidus was once considered a late surviving member of the family Rhomaleosauridae but has recently been identified as a close relative of polycotylids. There are several species of Leptocleidus but they are all are preserved in inshore/freshwater deposits. This lead Cruickshank (1997) to speculate that the large pliosaurids that appeared during the Middle and Late Jurassic outcompeted the Rhomaleosaurids in the open ocean and forced them to exploit near-shore niches.
There are presently three known valid species of Leptocleidus: L. superstes (the type species), L. capensis, and L. clemai. The genus 'Peyerus' was proposed for Leptocleidus capensis by Stromer (1935) but it is now considered a junior synonym of Leptocleidus(Cruickshank (1997).
Classification
Sauropterygia --> Eosauropterygia --> Eusauropterygia --> Pistosauroidea --> Plesiosauria --> Pliosauroidea --> Rhomaleosauridae
Leptocleidus superstes Andrews, 1922
Material
The holotype specimen, ???
Age and Location
Upper Weald Clay, Lower Cretaceous (Barremian) of Sussex, England.
Leptocleidus capensis (Andrews, 1911)
Material
The holotype specimen, ???
Age and Location
Sundays River Formation, Lower Cretaceous (Valangian) of Cape Province, South Africa.
Leptocleidus clemai (Cruickshank and Long, 1997)
Material
The holotype specimen, ???
Age and Location
???
Leptocleidus images
Cranium of Lepocleidus superstes (lateral view, top left; ventral (palatal) view, top right) and vertebrae. Length of vertebral series approx. 45cm (from Andrews, 1922).
>Pectoral girdle of L. superstes 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).
Illustration of the skull of L. capensis in dorsal view (from Cruickshank, 1997)
Illustration of the skull of L. capensis in lateral view (from Cruickshank, 1997)
Illustration of the skull of L. capensis in ventral (palatal) view (from Cruickshank, 1997)
