Pygostylia
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| Pygostylians Fossil range: Early Cretaceous – Recent |
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Pygostylia is a group of birds which includes Confuciusornis and all of the more derived birds; the Ornithothoraces. Chiappe (1997) defined the Pygostylia as "the common ancestor of the Confuciusornithidae and Neornithes (Ornithurae) plus all its descendants". This is a node - based definition.[1]
Chiappe (2001) united the Pygostylia in possessing four unambiguous synapomorphies. The trait that gives the group its name is the presence of a pygostyle. Next is the absence of a hyposphene - hypantrum. Next is a retroverted pubis separated from the main axis of the sacrum by an angle of 45 to 65 degrees. Last is a bulbous medial condyle of the tibiotarsus.[2]
[edit] References
- ^ Chiappe, L. (1997). "The Chinese early bird Confuciusornis and the paraphyletic status of Sauriurae." "Journal of Vertebrate Paleontology" 17(3)37A
- ^ Chiappe, Luis(2001) "Basal bird phylogeny" in "Mesozoic Birds: above the heads of dinosaurs". Chiappe and Witmer, ed. 2001, University of California Press
