Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Reptilia Linnaeus, 1758 - reptiles
     Subclass Diapsida Osborn, 1903 - diapsids see Clade Diapsida Osborn 1903 [Gauthier & de Queiroz 2020]
       Infraclass Archosauromorpha Huene, 1946 see Clade Archosauromorpha Huene 1946 [Benton 1985], nom. cl. inval.
         Superorder Archosauria Cope, 1869 - archosaurs see Clade Archosauria Cope 1869 [Gauthier & Padian 1985], nom. cl. inval.
           Order †Ornithischia Seeley, 1887
             1 Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
             2 Suborder †Stegosauria Marsh, 1877 see Infraorder Stegosauria Marsh, 1877
             3 Suborder †Ankylosauria Osborn, 1923 see Infraorder Ankylosauria Osborn, 1923
             4 Suborder †Ceratopia see Suborder Ceratopsia Marsh, 1890