Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass Ornithurae Haeckel, 1866 see Clade Ornithurae Haeckel 1866 [Gauthier 1986] {Chiappe 1991}
     Infraclass Carinatae Merrem, 1813 see Clade Carinatae Merrem 1813 [Gauthier & de Queiroz 2001]
       Order Pelecaniformes Sharpe, 1891
         Suborder Sulae Sharpe see Parvorder Sulida (Reichenbach, 1849) Sibley et al., 1988
           Family †Elopterygidae Lambrecht
             1 Genus †Elopteryx Andrews, 1913, nom. dub.
             2 Genus †Argillornis Owen, 1878
             3 Genus †Eostega Lambrecht, 1929