<==o SULAE [Suloidea Gragrft, 1985]
   |-- Sulidae (suulat)
   `--+-- Phalacrocoracidae (merimetsot)
      `--+-- †Plotopteridae (pingviinisuulat)
         `-- Anhingidae (käärmekaulat)


Reference(s):

Feduccia, A., 1980: The Age of Birds.

–Harvard University Press, Cambridge, Massachusetts & London, England, 1980, IX-196
Feduccia, A., 1997: The Origin and Evolution of Birds.

–Yale University Press, New Haven, 1996, x-420

Olson, S. L., 1975: Paleornithology of St. Helena Island, South Atlantic Ocean.

–Smithsonian Contributions to Baleobiology: Vol. 23, pp. iv-49

Olson, S. L., 1985: The fossil record of birds. 79-239.

in Farner, D., King, J. & Parkes, K. (eds.), 1985: Avian Biology. vol VIII.

–Academic Press, New York. 1985.

Sibley, C. G. & Monroe, J., BL., 1990: Distribution and taxonomy of birds of the world.

–Yale University Press, New Haven & London, 1990. XXIV-1111.