Ornithothoraces

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Cladus: Avemetatarsalia
Cladus: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauriformes
Cladus: Dracohors
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Eusaurischia
Subordo: Theropoda
Cladus: Neotheropoda
Cladus: Averostra
Cladus: Tetanurae
Cladus: Avetheropoda
Cladus: Coelurosauria
Cladus: Tyrannoraptora
Cladus: Maniraptoromorpha
Cladus: Maniraptoriformes
Cladus: Maniraptora
Cladus: Pennaraptora
Cladus: Paraves
Cladus: Eumaniraptora
Cladus: Avialae
Infraclassis: Aves
Cladus: Euavialae
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladi: Euornithes - †Enantiornithes
secundum Chiappe & Calvo, 1994

Cladus: Ornithothoraces
Cladi: Ornithurae – †Enantiornithes – †Iberomesornis – †Patagopteryx
secundum Cau, 2018

Cladus: Ornithothoraces
Cladi: Ornithuromorpha – †Enantiornithes
Name

Ornithothoraces Chiappe & Calvo, 1994: 239
Synonyms

Carinatae? Merrem, 1813
References
Primary references

Chiappe, L.M. & Calvo, J.O. 1994. Neuquenornis volans, a new Late Cretaceous bird (Enantiornithes, Avisauridae) from Patagonia, Argentina. Journal of Vertebrate Paleontology 14(2): 230–246. DOI: 10.1080/02724634.1994.10011554 ResearchGate Reference page.

Additional references

Cau, A. 2018. The assembly of the avian body plan: a 160-million-year long process. Bolletino della Società Paleontologica Italiana 57(1): 1–25. DOI: 10.4435/BSPI.2018.01 ResearchGate Reference page.

Ornithothoraces is a group of avialans that includes all enantiornithes ("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. In spite of this at least the sternum seems to have developed convergently rather than being a true homology.[1]

The earliest known members of the group are the enantiornitheans Protopteryx fengningensis, Eopengornis martini, and Cruralispennia multidonta, 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.[2] At least one other enantiornithean, Noguerornis gonzalezi, may be even older, at up to 145.5 million years ago, though its exact age is uncertain.[3]
Classification

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.[4] In 1998, Paul Sereno defined Ornithothoraces in the same way, but used Sinornis santensis instead of Iberomesornis romerali.[5]

The cladogram below follows the results of a phylogenetic analysis by Wang et al., 2016:[6]

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

Zheng, Xiaoting; Wang, Xiaoli; O'Connor, Jingmai; Zhou, Zhonghe (9 October 2012). "Insight into the early evolution of the avian sternum from juvenile enantiornithines". Nature Communications. 3 (1): 1116. Bibcode:2012NatCo...3.1116Z. doi:10.1038/ncomms2104. PMID 23047674.
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. Bibcode:2015NatCo...6.6987W. doi:10.1038/ncomms7987. PMC 5426517. PMID 25942493.
Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
Chiappe, Luis; Calvo, J.O. (1994). "Nequenornis volans, a new Late Cretaceous bird (Enantiornithes:Avisauridae) from Patagonia, Argentina". Journal of Vertebrate Paleontology. 14 (2): 230–246. doi:10.1080/02724634.1994.10011554.
Sereno, Paul (1998). "A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria". Neues Jahrbuch für Geologie und Paläontologie. 210: 41–83. doi:10.1127/njgpa/210/1998/41.
Wang, Min; Wang, Xiaoli; Wang, Yan; Zhou, Zhonghe (25 January 2016). "A new basal bird from China with implications for morphological diversity in early birds". Scientific Reports. 6 (1): 19700. Bibcode:2016NatSR...619700W. doi:10.1038/srep19700. PMC 4726217. PMID 26806355.