ARDEAE
  \-+--EURYPYGIMORPHAE
    |    |
    |    |--Eurypygiformes
    |    |    |--Rhynochetidae (Kagu)
    |    |    \--Eurypygidae (Sunbittern)
    |    |
    |    \--Phaethontiformes
    |         \--Phaethontidae (Tropicbirds)
    |
    |
    \-AEQUORNITHES
       \-+--Gaviiformes
         |    \--Gaviidae (Loons)
         \--+--+--Sphenisciformes
            |  |    \--Spheniscidae (Penguins)
            |  \--Procellariiformes
            |       \--+--Diomedeidae (Albatrosses)
            |          \--+--Oceanitidae (Southern Storm Petrels)
            |             \--+--Hydrobatidae (Northern Storm Petrels)
            |                \--Procellariidae (Petrels, Shearwaters)
            |
            |--Ciconiiformes
            |    \--Ciconiidae (Storks)
            \-+--Suliformes
              |    \--+--Fregatidae (Frigatebirds)
              |       \--+--Sulidae (Gannets, Boobies)
              |          \--+--Anhingidae (Anhingas)
              |             \--Phalacrocoracidae (Cormorants)
              \-+--Plataleiformes
                |    \--Threskiornithidae (Ibises, Spoonbills)
                \--+--Pelecaniformes
                   |   \--+--+--Scopidae (Hamerkop)
                   |      |  \--Balaenicipitidae (Shoebill)
                   |      \--Pelecanidae (Pelicans)
                   \--Ardeiformes
                        \--Ardeidae (Herons, Egrets, Bitterns)