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 †Hypsilophodontia Cooper, 1985 see Family Hypsilophodontidae Dollo, 1882
             Genus †Thescelosaurus Gilmore, 1913