<==o Caprimulgidae
   |?- †Ventivorus ragei
   |-- Chordeilinae (Haukkakehrääjät)
   `-- Caprimulginae (Varsinaiset kehrääjät)


Reference(s):

Feduccia, A., 1996: The Origin and Evolution of Birds.

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

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, B, L., 1990: Distribution and taxonomy of birds of the world.

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