Class [Reptilia] Linnaeus, 1758 - reptiles
   Subclass Lepidosauria Duméril & Bibron, 1839
     Order Rhynchocephalia Günther, 1867 - tuataras
       Suborder Sphenodontoidea Lydekker, 1888
         Family Sphenodontidae Cope, 1871 - tuataras
           Subfamily Sphenodontinae Cope, 1871
             1 Genus Sphenodon Gray, 1831
             2 Genus †Elachistosuchus Janensch, 1949
             3 Genus †Opisthias Gilmore, 1909
             4 Genus †Clevosaurus Swinton, 1939