Infraphylum Tetrapoda Goodrich, 1930 see Clade Tetrapoda Hatschek & Cori 1896 [Laurin 2020]
   Superclass Amniota Haeckel, 1866 see Clade Amniota Haeckel 1866 [Laurin & Reisz 2020]
     Paraclass Reptilia Linnaeus, 1758 [paraphyletic] - reptiles
       Parasubclass Diapsida Osborn, 1903 [paraphyletic] - diapsids see Clade Diapsida Osborn 1903 [Gauthier & de Queiroz 2020]
         Parainfraclass Archosauria Cope, 1869 [paraphyletic] see Clade Archosauria Cope 1869 [Gauthier & Padian 2020]
           Superorder †Ornithischia Seeley, 1887 see Order Ornithischia Seeley, 1887
             Paraorder †Pachycephalosauria Maryañska & Osmólska, 1974 [paraphyletic] see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
               ?Parafamily †Chaoyoungosauridae Zhao, 1983, nom. nud. [paraphyletic] see Family Chaoyangsauridae Zhao, Cheng, & Xu, 1999
                 1 Genus †Chaoyoungosaurus Zhao, 1983, nom. nud. see Genus Chaoyangsaurus Zhao, Cheng & Xu, 1999
                 2 Genus †Xuanhuasaurus Zhao, 1985, nom. nud. see Genus Xuanhuaceratops Zhao X., Cheng Z., Xu X. & Makovicky, 2006