Pygostylia

Taxobox
name = Pygostylians
fossil_range = Early Cretaceous – Recent


image_width = 200px
image_caption =
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Aves
unranked_ordo = Ornithurae
unranked_familia = Pygostylia
unranked_familia_authority = Chiappe, 1997
subdivision_ranks = Daughter clades
subdivision =
* Confuciusornithidae
* Ornithothoraces

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.Chiappe, L. (1997). "The Chinese early bird "Confuciusornis" and the paraphyletic status of Sauriurae." "Journal of Vertebrate Paleontology" 17(3)37A]

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.Chiappe, Luis(2001) "Basal bird phylogeny" in "Mesozoic Birds: above the heads of dinosaurs". Chiappe and Witmer, ed. 2001, University of California Press]

References