Sauropterygia–> Eosauropterygia–> Eusauropterygia–> Pistosauroidea–> Plesiosauria–>Plesiosauroidea–> Euplesiosauria–> Cryptoclididae
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 also included the derived Cretaceous plesiosaurs Aristonectes and Kaiwhekea within the Cryptoclididae. However, other authors regard these Cretaceous taxa as elasmosaurids (Gasparini et al. 2003), in which case cryptoclidids would be absent from Cretaceous strata and restricted to the Jurassic.
- Aristonectes According to Cruickshank and Fordyce (2002)
- Kaiwhekea According to Cruickshank and Fordyce (2002)