Order †Ornithischia Seeley, 1887 Parvorder †Genasauria Sereno, 1986 see Clade Genasauria Sereno 1986 Nanorder †Cerapoda Sereno, 1986 see Suborder Cerapoda Sereno, 1986 Hypoorder †Euornithopoda Sereno, 1986 see Clade Euornithopoda Sereno 1986 1 Suborder †Heterodontosauria Cooper, 1985 see Family Heterodontosauridae Romer, 1966 2 Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881