Diapsida Osborn 1903 [Laurin 1991] see Clade Diapsida Osborn 1903 [Gauthier & de Queiroz 2020]
   Archosauromorpha xxxHuene 1946 [Gauthier, Kluge & Rowe 1988] see Clade Archosauromorpha Huene 1946 [Benton 1985], nom. cl. inval.
     Archosauria Cope, 1869
       Ornithosuchia see [unranked] Avesuchia Benton, 1999
         Ornithodira Gauthier 1986 see Clade Ornithodira Gauthier 1986 [M. Ezcurra, S. Nesbitt, M. Bronzati, F. Dalla Vecchia, F. Agnolin, R. Benson, ..., M. Langer 2020]
           Dinosauria Owen 1841 [Padian & May 1993], nom. cl. inval. see Clade Dinosauria Owen 1842 [Langer, Novas, Bittencourt, Ezcurra & Gauthier 2020]
             †Ornithischia Seeley 1887 [Padian & May 1993] see Order Ornithischia Seeley, 1887
               †Genasauria Sereno 1986
                 †Cerapoda Sereno, 1986 see Suborder Cerapoda Sereno, 1986
                   †Ornithopoda Marsh 1881 see Infraorder Ornithopoda Marsh, 1881
                     †Euornithopoda Sereno 1986
                       †Iguanodontia Dollo 1888
                         †Ankylopollexia Sereno 1986
                           †Styracosterna Sereno 1986
                             Family †Hadrosauridae Cope, 1869 - hadrosaurs