Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
Count: 28o;94f;139g;10s; ‡2o;4f;17g; †3o;34f;315g;10s
   Subclass †Odontoholcae (Marsh, 1875) Stejneger, 1885 see Cohort Ornithurae Haeckel, 1866
  Count: [†*] †1o;1f;2g;4s
     Order †Hesperornithiformes Fürbringer, 1888
    Count: -
       Family †Hesperornithidae Marsh, 1872
      Count: [†*] †2g;4s
         1 Genus †Hesperornis Marsh, 1872
        Count: [†*] †3s
         2 Genus †Coniornis Marsh, 1893
        Count: [†*] †1s