Phylum Chordata Bateson, 1885 - chordates
   Subphylum Vertebrata Cuvier, 1812 - vertebrates see Infraphylum Vertebrata Lamarck, 1801
     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
               Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
                 1 Family †Heterodontosauridae Romer, 1966
                 2 Family †Hypsilophodontidae Dollo, 1882
                 3 Family †Dryosauridae Stefano, 1903
                 4 Family †Thescelosauridae Sternberg, 1937
                 5 Family †Camptosauridae Marsh, 1885
                 6 Family †Iguanodontidae Cope, 1869
                 7 Family †Hadrosauridae Cope, 1869 - hadrosaurs
                 8 Family †Lambeosauridae see Subfamily Lambeosaurinae Parks, 1923