Liopleurodon is a pliosaur that hardly needs introduction since appearing as the villain in the BBC’s ‘Walking with Dinosaurs’ TV series. This led to popular misconceptions about the size of Liopleurodon, which is known to have reached adult sizes in the region of seven metres long, nowhere near the gargantuan 25m estimate proposed by the series and later perpetuated elsewhere.
Liopleurodon differs from Pliosaurus in the following characters: relatively short mandibular symphysis with 5-7 teeth adjacent to it), each lower jaw ramus contains 25-28 teeth, the teeth have fewer longitudinal ridges on outer (labial) surface relative to the inner (lingual) surface, and relatively longer epipodial bones in the limbs. 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 relationships of Jurassic pliosaurus are still poorly understood. The species macromerus, previosuly included by some authors in Pliosaurus and by others in Liopleurodon, may turn out to be a distict genus.
Also, Liopleurodon was in no way magical, Charlie.
Liopleurodon ferox
Species
L. ferox
Author
Sauvage, 1873
Classification
Sauropterygia
Eosauropterygia
Eusauropterygia
Pistosauroidea
Pistosauria
Plesiosauria
Pliosauroidea
Pliosauridae
Liopleurodon
Age
Callovian, Middle Jurassic
Type location
Peterborough, England. Also known from Bedfordshire (UK), Cambridgeshire (UK), France (near Boulogne) and possibly Chile.
Type specimen
the holotype is only a single tooth
Referred material
Known from several partial skeletons and skulls
Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. 
Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. 
Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. 
Close up of the skull of the mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. Photo by Markus Felix Bühler 
Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany 
Skull of Liopleurodon ferox in dorsal and ventral view. From Andrews (1897). 
Skull of Liopleurodon ferox in lateral view and posterior view. From Noe et. al. (2003). 
Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany (from Martill and Naish, 2000). 
Associated skeleton referred to Liopleurodon ferox (from Tarlo, 1960). 
Skeleton and muscular reconstruction of Liopleurodon ferox in lateral view. From Newman and Tarlo (1967). This reconstruction is probably a composite of several specimens of Liopleurodon and Pliosaurus. 
Skeleton of Liopleurodon ferox in dorsal view. From Newman and Tarlo (1967). This reconstruction is probably a composite of several specimens of Liopleurodon and Pliosaurus. 
Close up of the skull of the mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. Photo by Markus Felix Bühler 
Close up of the skull of the mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany. Photo by Markus Felix Bühler
Liopleurodon pachydeirus
Species
L. pachydeirus
Author
(Seeley, 1869)
Classification
Sauropterygia
Eosauropterygia
Eusauropterygia
Pistosauroidea
Pistosauria
Plesiosauria
Pliosauroidea
Pliosauridae
Liopleurodon
Age
Callovian, Middle Jurassic
Type location
Great Gransden, UK
Type specimen
Associated cervical vertebrae
Referred material
-
According to Tarlo (1960), L. pachydeirus differs from L. ferox in the morphology of its teeth and cervical vertebrae. L. pachydeirus has enamel ridges closely packed on inner surface and 6-7 evenly spaced ridges on outer surface, cervical vertebrae with faint ventral keel (Tarlo, 1960).
