Temporal range: Early Cretaceous–Recent, 131–0 Ma
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 (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.
The pygosylians fall into two distinct groups with regard to the pygostyle. The Ornithothoraces have a ploughshare-shaped end, while the more primitive members have a longer, rod-shaped pygostyle.
The earliest known member of the group is the enantiornithine species Protopteryx fengningensis, from the Sichakou Member of the Huajiying Formation of China, which dates to around 131 Ma ago, though at least one other enantiornithine, Noguerornis, may be even older, at up to 145.5 million years ago, though its exact age is uncertain.
- ^ Chiappe, L. (1997)
- ^ Chiappe, Luis (2001)
- ^ O'Connor, J.K., Zhou Z. and Zhang F. (In press). "A reappraisal of Boluochia zhengi (Aves: Enantiornithes) and a discussion of intraclade diversity in the Jehol avifauna, China." Journal of Systematic Palaeontology, (published online before print 16 December 2010). doi:10.1080/14772019.2010.512614
- ^ Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
- Chiappe, L. (1997). "The Chinese early bird Confuciusornis and the paraphyletic status of Sauriurae". Journal of Vertebrate Paleontology. 3. 17 (37A).
- Chiappe, Luis (2001). Chiappe, Luis; Witmer,, eds. Basal bird phylogeny in Mesozoic Birds: above the heads of dinosaurs. University of California Press.
|This article is part of Project Bird Taxonomy, a All Birds project that aims to write comprehensive articles on every order, family and other taxonomic rank related to birds.|