Phylum [Vertebrata] (Lamarck, 1801)
   Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
     Subclass †Odontornithes (Marsh, 1873)
       Order †Ichthyornithiformes Marsh, 1873
         Genus †Ichthyornis Marsh, 1872