Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass †Odontoholcae (Marsh, 1875) Stejneger, 1885 see Cohort Ornithurae Haeckel, 1866
     Order †Hesperornithiformes Fürbringer, 1888
       Family †Hesperornithidae Marsh, 1872
         1 Genus †Hesperornis Marsh, 1872
         2 Genus †Coniornis Marsh, 1893