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
         Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
           Infraorder †Iguanodontia Dollo, 1888 see Clade Iguanodontia Dollo 1888
             Gigafamily †Dryomorpha Sereno, 1986 see Clade Dryomorpha Sereno 1986 [D. Madzia, V.M. Arbour, C.A. Boyd, A.A. Farke, P. Cruzado-Caballero & D.C. Evans 2021]
               Megafamily †Dryosauroidea Milner & Norman, 1984 see Family Dryosauridae Stefano, 1903
                 1 Genus †Dryosaurus Marsh, 1894
                 2 Genus †Valdosaurus Galton, 1977