Phylum Chordata Bateson, 1885 - chordates
   Subphylum Vertebrata Cuvier, 1812 - vertebrates
     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 Family †Fabrosauridae Galton, 1972
               2 Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
               3 Suborder †Scelidosauria (Seeley, 1892)
               4 Suborder †Stegosauria Marsh, 1877 see Infraorder Stegosauria Marsh, 1877
               5 Suborder †Ankylosauria Osborn, 1923 see Infraorder Ankylosauria Osborn, 1923
               6 Suborder †Pachycephalosauria Maryañska & Osmólska, 1974 see Infraorder Pachycephalosauria Maryañska & Osmólska, 1974
               7 Suborder †Ceratopsia Marsh, 1890 see Infraorder Ceratopsia Marsh, 1890