The family Cryptoclididae contains a variety of moderately sized long-necked plesiosaurs. Synapomorphies (shared unique characters) for this group include a narrow vertical jugal bar,an enlarged orbit, and a deep excavated ventral cheek margin Brown et al. 1994).
Genera included in this family vary depending on the classification, but Cryptoclidus, Tricleidus, Pantasaurus, Tatenectes, Kimmerosaurus, Vinialesaurus and Muraenosaurus are typically included within this group. Some authors have included the derived Cretaceous plesiosaurs Aristonectes and Kaiwhekea within the Cryptoclididae (Cruickshank and Fordyce, 2002). However, more recent studied have classified these Cretaceous taxa as elasmosaurids (Gasparini et al. 2003), in which case cryptoclidids are absent from Cretaceous strata and restricted to the Jurassic.
Abyssosaurus is a derived cryptoclidid plesiosaur from the Upper Hauterivian (Lower Cretaceous) of the Menya River, Chuvashia, Russia. It was named and described in 2011 by Alexander Yu Berezin (Berezin 2011). A partial skull associated with the holotype specimen (MChEIO, no. PM/1) was not described in the original 2011 paper but was discovered later in …
The genus and species ‘Apractocleidus teretipes‘ was erected by Smellie (1916) for a specimen now regarded as old-adult individual of Cryptoclidus. The specimen was collected by Alfred Leeds and acquired by the Hunterian Museum, Glasgow. The taxon ‘Apractocleidus‘ is therefore considered a junior synonym of Cryptoclidus. The holotype and only specimen is mounted on display …
Cryptoclidus, often wrongly spelled ‘Cryptocleidus’ after Andrews (1909), is a moderately sized plesiosaur up to 3 metres long. 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 old adult individuals. This makes Cryptoclidus …
Kimmerosaurus is a poorly known cryptoclidid plesiosaur known only from skull and neck material (Brown, 1981; Brown et. al. 1986). It differs from other plesiosaurs in the large number of needle-like teeth in its jaws, and in the form of its teeth, which are completely smooth and lack the longitidinal ridges present in other plesiosaurs. …