Subclass Avialae Gauthier, 1986 see Clade Avialae Gauthier 1986
   Infraclass Aves Linnaeus, 1758 see Subclass Aves Linnaeus, 1758
     Parvclass Neornithes Gadow, 1893 see Subclass Neornithes Gadow, 1893
       Cohort Neognathae Pycraft, 1900
         Subcohort Neoaves Sibley et al., 1988
           Division Natatores Baird, 1858
             Subdivision Stegano-grallatores B.C. Livezey & R.L. Zusi, 2007
               Superorder Pelecanimorphae Huxley, 1867
                 Order Pelecaniformes Sharpe, 1891
                   Suborder Steganopodes Chandler, 1916
                     Infraorder Pelecanides Sharpe, 1891
                       1 Parvorder Pelecanida (Sharpe, 1891) B.C. Livezey & R.L. Zusi, 2007
                       2 Parvorder Sulida (Reichenbach, 1849) Sibley et al., 1988