Order †Ornithischia Seeley, 1887
   Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
     Family †Hypsilophodontidae Dollo, 1882
       Genus †Dryosaurus Marsh, 1894
       Genus †Hypsilophodon Huxley, 1870
       Genus †Othniella see Genus Othnielia Galton, 1977, nom. dub.
       Genus †Parksosaurus Sternberg, 1937
       Genus †Tenontosaurus Ostrom, 1970
       Genus †Thescelosaurus Gilmore, 1913