Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Goodrich, 1930
         Amniota Haeckel, 1866 - amniotes
           Class Reptilia Linnaeus, 1758 [paraphyletic] - reptiles
             Subclass Diapsida Osborn, 1903 - diapsids see Clade Diapsida Osborn 1903 [Laurin 1991]
               Infraclass Archosauromorpha Huene, 1946 see Clade Archosauromorpha Huene 1946 [Gauthier, Kluge & Rowe 1988] {Laurin 1991}
                 Superorder Archosauria Cope, 1869 - archosaurs see Clade Archosauria Cope 1869 [Gauthier & Padian 1985]
                   †Dinosauria Owen 1841
                     Order †Ornithischia Seeley, 1887
                       Suborder †Ornithopoda Marsh, 1871 see Infraorder Ornithopoda Marsh, 1881
                         Family †Hadrosauridae Cope, 1869 - hadrosaurs