Dinosauria Owen 1841 [Padian & May 1993], nom. cl. inval. see Clade Dinosauria Owen 1842 [Langer, Novas, Bittencourt, Ezcurra & Gauthier 2020]
Count: -
   †Ornithischia Seeley 1887 [Padian & May 1993] see Order Ornithischia Seeley, 1887
  Count: -
     †Genasauria Sereno 1986
    Count: -
       †Neornithischia Cooper 1985
      Count: -
         †Ornithopoda Marsh 1881 see Infraorder Ornithopoda Marsh, 1881
        Count: -
           †Euornithopoda Sereno 1986
          Count: -
             †Iguanodontia Dollo 1888
            Count: -
               †Ankylopollexia Sereno 1986
              Count: -
                 †Styracosterna Sereno 1986
                Count: -
                   †Hadrosauriformes Sereno 1997
                  Count: -
                     1 †Iguanodontidae Cope 1869 see Family Iguanodontidae Cope, 1869
                    Count: -
                     2 †Hadrosauroidea Sereno 1986 see Superfamily Hadrosauroidea Cope, 1869
                    Count: -