Brown (1981) diagnosed Muraenosaurus as follows: "Plesiosauroids in which the teeth are ornamented with many longitudinal ridges; the dentary bears 19 to 22 teeth on each ramus; the premaxillae bear 5 teeth each, of which the 1st and 5th are small, and the 2nd to 4th are large; the most anterior maxilliary…
Microcleidus is a medium (4.27 m) to large (5.03 m) plesiosauroid with a small head and a long neck containing 38–39 cervical vertebrae. Watson (1909) erected Microcleidus to accommodate fossil material belonging to 'P.' homalospondylus and 'P.' macropterus (Watson 1911). Both species were considered valid by Seeley (1865), Blake (1876) and Watson (1911) on…
'Occitanosaurus' was described by Sciau et al. (1990) and Bardet et al. (1999). The genus name was erected for 'Plesiosaurus' tournemirensis by Bardet et al. (1999). The taxon was originally regarded as an early elasmosaurid but is now considered a member of the Microcleididae. 'Occitanosaurus' was approximately 3.9 meters long. The type…
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…
Cryptoclidus, often wrongly spelled 'Cryptocleidus' after Andrews (1909), is a moderately sized plesiosaur with adults about four metres long (Brown 1981). It is known from a large number of individual specimens from the Oxford Clay Formation. Fossils of Cryptoclidus are relatively common, and provide a complete ontogenetic sequence from very young to…