Ornithothoraces

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Ornithothoracines
Temporal range:
Early CretaceousPresent, 131–0 Ma
Liaoxiornis delicatus.JPG
Fossil of a juvenile enantiornithine (Liaoxiornis delicatus)
Southern Ground Hornbill.JPG
Southern ground hornbill (Bucorvus leadbeateri)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Pygostylia
Clade: Ornithothoraces
Chiappe & Calvo, 1994
Subgroups

Ornithothoraces is a group of avialans that includes all enantiornithines ("opposite birds") and the euornithes ("true birds"), which includes modern birds and their closest ancestors. The name Ornithothoraces means "bird thoraxes". This refers to the modern, highly advanced anatomy of the thorax that gave the ornithothoracines superior flight capability compared with more primitive avialans. This anatomy includes a large, keeled breastbone, elongated coracoids and a modified glenoid joint in the shoulder, and a semi-rigid rib cage.

The earliest known members of the group are the enantiornithes Protopteryx fengningensis and Eopengornis martini, as well as the euornithine Archaeornithura meemannae, all from the Sichakou Member of the Huajiying Formation in China, which has been dated to 130.7 million years old.[1] At least one other enantiornithine, Noguerornis gonzalezi, may be even older, at up to 145.5 million years ago, though its exact age is uncertain.[2]

Classification[edit]

In 1994, Chiappe and Calvo established a phylogenetic definition of the group. They defend Ornithothoraces as a node-based clade, the common ancestor of Iberomesornis romerali and modern birds, and all of its other descendants.[3] In 1998, Paul Sereno defined Ornithothoraces in the same way, but used Sinornis santensis instead of Iberomesornis romerali.[4]

The cladogram below follows the results of a phylogenetic analysis by Wang et al., 2016:[5]


Ornithothoraces
Enantiornithes


Protopteryx



Pengornithidae






Eoenantiornis



Bohaiornithidae





Fortunguavis




Longipterygidae




Eocathayornis




Cathayornis




Vescornis



Neuquenornis



Gobipteryx



Eoalulavis




Qiliania



Concornis










Euornithes

Archaeorhynchus


Ornithuromorpha

Patagopteryx



Vorona




Schizooura




Hongshanornithidae




Jianchangornis




Songlingornithidae




Gansus




Apsaravis



Ornithurae












References[edit]

  1. ^ Wang, M.; Zheng, X.; o’Connor, J. K.; Lloyd, G. T.; Wang, X.; Wang, Y.; Zhang, X.; Zhou, Z. (2015). "The oldest record of ornithuromorpha from the early cretaceous of China". Nature Communications. 6: 6987. doi:10.1038/ncomms7987. PMID 25942493. 
  2. ^ Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
  3. ^ Chiappe, Luis; Calvo, J.O. (1994). "Nequenornis volans, a new Late Cretaceous bird (Enantiornithes:Avisauridae) from Patagonia, Argentina". Journal of Vertebrate Paleontology. 14: 230–246. doi:10.1080/02724634.1994.10011554. 
  4. ^ Sereno, Paul (1998). "A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria". Neues Jahrbuch fur Geologie und Palaontologie. 210: 41–83. 
  5. ^ Wang M., Wang X., Wang Y., and Zhou Z. (2016). A new basal bird from China with implications for morphological diversity in early birds. Scientific Reports, 6: 19700. doi:10.1038/srep19700.