Liopleurodon Sauvage, 1873
Liopleurodon is a pliosaur that hardly needs introduction since appearing as the lead villain in the BBC's 'Walking with Dinosaurs' series. This series led to misconceptions about the size of Liopleurodon, which is known to have reached adult sizes in the region of 7m, nowhere near the gargantuan 25m estimate proposed by the series and perpetuated elsewhere. It should also be pointed out that Liopleurodon was in no way magical, Charlie.
Liopleurodon differs from Pliosaurus in the following characters: mandibular symphysis relatively short (5-7 teeth), each ramus (jaw) contains 25-28 teeth, fewer longitudinal ridges on outer surface of teeth than on inner surface, long epipodials. According to the classification of Tarlo (1960), the teeth of callovian species of Liopleorodon (L. ferox) are circular in cross section, whereas they are trihedral (triangular in cross section) in later Kimmeridgian species (L. rossicus, L. macromerus). A similar trend occurs in the closely related genus Pliosaurus. However, revision of Jurassic pliosaurid taxonomy is underway and the interelationships of Jurassic pliosaurus are still poorly understood. The species macromerus, included by some authors in Pliosaurus and by others in Liopleurodon, may turn out to be a distict genus.
Classification
Sauropterygia --> Eosauropterygia --> Eusauropterygia --> Pistosauroidea --> Plesiosauria --> Pliosauroidea --> Pliosauridae
L. ferox Conybeare, 1824
L. ferox is the type species of Liopleurodon.
Material
Known from various partial skeletons. However, the holotype is only a single tooth.
Age and Location
Callovian, Oxford Clay, Peterborough, England. Also known from Bedfordshire (UK), Cambridgeshire (UK), France (near Boulogne) and possibly Chile.
Liopleurodon ferox images
L. pachydeirus (Seeley, 1869)
Differs from L. ferox in features of the teeth and cervical vertebrae: enamel ridges closely packed on inner surface and 6-7 evenly spaced ridges on outer surface, cervical vertebrae with faint ventral keel (Tarlo, 1960).
Material
The holotype is some associated cervical vertebrae
Age and Location
Oxford Clay, Great Gransden, UK
L. rossicus (Novozilov, 1948)
Pending reevaluation of the material, this species may not in fact belong to Liopleurodon.
Material
The holotype includes most of a skull and pectoral girdle
Age and Location
Middle Volgian (Dorsoplanites panderi Zone), Buinsk Mine Oil Shales, Ibresi Disatrict, right bank of river Volga, Autonomous republic of Chuvashia, Russia.
Liopleurodon rossicus images
L. macromerus (Phillips, 1871)
As a result of the confused systematics of pliosaurids, this species, originally attributed to Pliosaurus and later erroneously assigned to its own genus (Stretosaurus) (Tarlo 1959), has been bouncing between Liopleurodon and Pliosaurus ever since. A recent review of Kimmeridgian pliosaur taxonomy concluded that "all material currently referred to Liopleurodon macromerus must revert back to the original combination of Pliosaurus macromerus." (Noe et al. 2004)
Material
The Lectotype is an anterior cervical centrum. Tarlo (1959) referred several specimens (as syntypes) and a partial skeleton discoved in Stretham to this species
Age and Location
Kimeridge Clay
