In 2006, Bonaparte and Sues finally gave "clevosaurs" a formal name and taxonomic rank as the family Clevosauridae. They defined Clevosauridae as the last common ancestor of Clevosaurus, Brachyrhinodon, and Polysphenodon, and all of its descendants. In 2015, the definition of this family was revised to be "all taxa more closely related to Clevosaurus than to Sphenodon". However, the erection of this family conflicts with their position within Sphenodontidae, as a taxonomic family cannot be within another family. Sources which use Sphenodontidae as a wide group of sphenodontians do not use the term Clevosauridae, instead continuing to use the informal term 'clevosaurs'. On the other hand, sources which use Clevosauridae do not use Sphenodontidae. Some do not use either family, instead opting for 'clevosaurs' and 'advanced sphenodontians'.
