Chordata Bateson, 1885 - chordates
   Vertebrata Cuvier, 1812 - vertebrates
     Reptilia Linnaeus, 1758 - reptiles
       Diapsida Osborn, 1903 - diapsids see Clade Diapsida Osborn 1903 [Gauthier & de Queiroz 2020]
         Archosauromorpha Huene, 1946 see Clade Archosauromorpha Huene 1946 [Benton 1985], nom. cl. inval.
           Archosauria Cope, 1869 - archosaurs see Clade Archosauria Cope 1869 [Gauthier & Padian 1985], nom. cl. inval.
             †Ornithischia Seeley, 1887
               †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
                 †Chaoyoungosauridae
                   †Xuanhuasaurus Chao, 1985, nom. nud.