<==o APODI (kirskujat)
   |?-o †Jungornithidae
   |  |-- †Argornis caucasicus
   |  `--+?- †Jungornis tesselatus
   |     `-- †Palescyvus escampensis
   |--o †Laputavis M. Eoc. WEu. [=? Laputa Dyke, 2001]
   |  `-- †L. robusta (Dyke, 2001) [Laputa robusta Dyke, 2001]
   `--+--o †Aegialornithidae
      |  |?- †Cypselavus gallicus Gaillard, 1908
      |  |--o †Aegialornis
      |  |  |-- †A. gallicus [=? Cypselavus gallicus Gaillard, 1908]
      |  |  |-- †A. leenhardti
      |  |  |-- †A. wetmorei
      |  |  `-- †A. broweri
      |  `--+-- †Primapus lacki Harrison & Walker
      |     `--o †Scaniacypselus Harrison, 1984; M. Eoc. WEu.
      |        |-- †S. wardi Harrison, 1984
      |        `-- †S. szarskii (Peters, 1985) Meyr & Peters, 1999 [Aegialornis szarskii Peters, 1985, Primapus szarskii (Peters, 1985) Mourer-Chauviré, 1988]
      `--+--o Hemiprocne [Hemiprocnidae] (puukiitäjät, -kirskujat)
         |  |-- H. coronata (Crested Treeswift)
         |  |-- H. longipennis (töyhtökiitäjä)
         |  |-- H. mystacea (isopuukiitäjä)
         |  `-- H. comata (pikkupuukiitäjä)
         `--+-- †Eocypselus vincenti Harrison
            `--o Apodidae (kirskujat)
               |-- Cypseloidinae (Nokikirskujat[kiitäjät) [Recent: 4 genera / 16 species]
               `-- Apodinae (Varsinaiset kirskujat[Kiitäjät) [Recent: 17/90]


Reference(s):

    Dyke, G. J., 2001: A primitive swift from the London Clay and the relationships of fossil apodiform birds.
–Journal of Vertebrate Paleontology: Vol. 21, #1, pp. 195-200

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

–Harvard University Press, Cambridge, Massachusetts & London, England, 1980, IX-196
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, J., BL. 1990:
 Distribution and taxonomy of birds of the world.
--Yale University Press, New Haven & London, 1990. XXIV-1111.