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Gigantornis Temporal range: Middle Eocene
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	†Odontopterygiformes
Family:	†Pelagornithidae
Genus:	†Gigantornis Andrews, 1916
Species:	†G. eaglesomei
Binomial name
†Gigantornis eaglesomei Andrews, 1916

Gigantornis eaglesomei is a very large prehistoric bird described from a fragmentary specimen from the Eocene of Nigeria. It was originally described as a representative of the albatross family, Diomedeidae, but was later referred to the pseudotooth or bony-toothed bird family, Pelagornithidae. Gigantornis is one of the largest pseudotooth birds, with an inferred wingspan of about 6 m (20 ft) it is among the largest birds ever.

Its identified remains consist of a broken sternum found in Middle Eocene Ameki Formation deposits at Ameki (Nigeria). The fossil bird was considered to belong the albatross family (Diomedeidae), as no sterna of pseudotooth birds were known until its discovery, and it remained the only such specimen for decades. Only in the 1970s its true affinities were realized, after it had become clear that although it must have been from a dynamic soarer with wings like an albatross, it resembled pelicans (order Ciconiiformes) rather than tubenoses (order Procellariiformes, to which albatrosses belong) in its details.

It is not known whether this bird belongs to a distinct genus; it might even be the very same species as the similar-sized Dasornis emuinus, whose fossils are not uncommon in the Ypresian (Early Eocene) London Clay of the Isle of Sheppey (England). Remains of a large pseudotooth bird were also found in the Middle Eocene of Kpogamé-Hahotoé (Togo) and have been provisionally termed "Aequornis traversei"; their analysis is likely to provide at least some insight on the taxonomic status of G. eaglesomei.

The Gigantornis sternum is of the typical short and deep-crested shape found in dynamic soarers. Compared to LHNB (CCCP)-1, a Middle to Late Miocene pseudotooth bird sternum found in Portugal and tentatively assigned to Pelagornis, its articular facet for the furcula consists of a flat section at the very tip of the sternal keel and a similar one set immediately above it at an outward angle, and the spina externa is shaped like an Old French shield in cross-section. The slightly smaller LHNB (CCCP)-1 has a less sharply protruding sternal keel, the articular facet for the furcula consists of a large knob at the forward margin, and the spina externa is narrow in cross-section.

Footnotes

1. Olson (1985: p.200), Bourdon (2005), Mayr (2009: p.59), Mayr et al. (2008)
2. Formerly Pelecaniformes; see there
3. Andrews (1916), Brodkorb (1963: p.241), Olson (1985: p.196), Mayr (2009: p.56,58)
4. Published in a thesis and hence a nomen nudum: ICZN (1999)
5. Bourdon (2006), Mayr (2009: p.56)
6. Mayr et al. (2008)

References

• Andrews, C.W. (1916). "Note on the sternum of a large carinate bird from the (?) Eocene of Southern Nigeria". Proceedings of the Zoological Society of London. 86 (3): 519–524. doi:10.1111/j.1096-3642.1916.tb02030.x.
• Bourdon, Estelle (2005): Osteological evidence for sister group relationship between pseudo-toothed birds (Aves: Odontopterygiformes) and waterfowls (Anseriformes). Naturwissenschaften 92(12): 586–591. doi:10.1007/s00114-005-0047-0 (HTML abstract) Electronic supplement (requires subscription)
• Bourdon, Estelle (2006): L'avifaune du Paléogène des phosphates du Maroc et du Togo: diversité, systématique et apports à la connaissance de la diversification des oiseaux modernes (Neornithes) . Doctoral thesis, Muséum national d'histoire naturelle . HTML abstract
• Brodkorb, Pierce (1963): Catalogue of fossil birds. Part 1 (Archaeopterygiformes through Ardeiformes). Bulletin of the Florida State Museum, Biological Sciences 7(4): 179–293. PDF or JPEG fulltext Archived 2007-03-11 at the Wayback Machine
• International Commission on Zoological Nomenclature (ICZN) (1999): International Code of Zoological Nomenclature (4th ed.). International Trust for Zoological Nomenclature, London. ISBN 0-85301-006-4 HTML fulltext
• Mayr, Gerald (2009): Paleogene Fossil Birds. Springer-Verlag, Heidelberg & New York. ISBN 3-540-89627-9
• Mayr, Gerald; Hazevoet, Cornelis J.; Dantas, Pedro; & Cachāo, Mário (2008): A sternum of a very large bony-toothed bird (Pelagornithidae) from the Miocene of Portugal. J. Vertebr. Paleontol. 28(3): 762–769. DOI:10.1671/0272-4634(2008)282.0.CO;2 HTML abstract
• Olson, Storrs L. (1985): The Fossil Record of Birds. In: Farner, D.S.; King, J.R. & Parkes, Kenneth C. (eds.): Avian Biology 8: 79-252. PDF fulltext Archived 2011-07-18 at the Wayback Machine

v t e Maniraptora
Kingdom: Animalia Phylum: Chordata Clade: Dinosauria Clade: Theropoda Clade: Maniraptoriformes Avemetatarsalia see Avemetatarsalia Theropoda see Theropoda Maniraptora see below↓
Maniraptora Maniraptora †Elopteryx? †Fukuivenator? †Kakuru? †Migmanychion †Yaverlandia? †Alvarezsauroidea Achillesaurus Aorun? Bannykus Bonapartenykus Haplocheirus Patagonykus Shishugounykus Tugulusaurus? Xiyunykus Alvarezsauridae Achillesaurus? Alnashetri Alvarezsaurus Bonapartenykus? Bradycneme Heptasteornis Patagonykus? Parvicursorinae Dzharaonyx Jaculinykus Khulsanurus Kol? Nemegtonykus Ondogurvel Parvicursor Qiupanykus Trierarchuncus Ceratonykini Albinykus Ceratonykus Xixianykus Mononykini Albertonykus Linhenykus Mononykus Shuvuuia †Therizinosauria Eshanosaurus? Falcarius Fukuivenator? Jianchangosaurus Lingyuanosaurus Therizinosauroidea Alxasaurus Beipiaosaurus Enigmosaurus Martharaptor Suzhousaurus Therizinosauridae Erliansaurus Erlikosaurus Nanshiungosaurus Neimongosaurus Nothronychus Paralitherizinosaurus Segnosaurus Therizinosaurus Pennaraptora †Oviraptorosauria see Oviraptorosauria Paraves see below↓
Paraves Paraves †Palaeopteryx? †Pneumatoraptor †Rahonavis †Scansoriopterygidae? Ambopteryx Epidexipteryx Scansoriopteryx Yi †Anchiornithidae Anchiornis Aurornis Caihong Eosinopteryx Fujianvenator Liaoningvenator? Ostromia Pedopenna Serikornis Xiaotingia Yixianosaurus †Archaeopterygidae Alcmonavis? Archaeopteryx Wellnhoferia Anchiornithidae? †Dromaeosauridae see Dromaeosauridae †Troodontidae see Troodontidae Avialae †Alcmonavis †Balaur? †Cretaaviculus? †Fukuipteryx †Overoraptor †Rahonavis? †Yandangornis †Zhongornis †Anchiornithidae? †Archaeopterygidae? †Scansoriopterygidae? †Jeholornithiformes Dalianraptor? Jeholornis Jixiangornis? Kompsornis Neimengornis Pygostylia †"Proornis" †Omnivoropterygidae? Omnivoropteryx Sapeornis †Confuciusornithidae Changchengornis Confuciusornis Eoconfuciusornis Yangavis †Jinguofortisidae Chongmingia Cratonavis Jinguofortis Ornithothoraces †Enantiornithes see Enantiornithes Euornithes see below↓
Euornithes Euornithes †Archaeorhynchus †Bellulornis †Brevidentavis †Changmaornis †Changzuiornis †Chaoyangia †Dingavis †Eogranivora †Gargantuavis? †Hollanda †Horezmavis †Jianchangornis †Jiuquanornis †Juehuaornis †Kaririavis †Meemannavis †Platanavis †Vorona †Wyleyia? †Xinghaiornis †Yumenornis †Zhongjianornis †Schizoouridae Mengciusornis Schizooura †Patagopterygiformes Alamitornis Kuszholia? Patagopteryx †Ambiortiformes Ambiortus Apsaravis? Palintropus? †Hongshanornithidae Archaeornithura Hongshanornis Longicrusavis Parahongshanornis Tianyuornis †Songlingornithidae Hollanda? Piscivoravis? Songlingornis Yanornis? Yixianornis? †Yanornithidae Abitusavis Similiyanornis Yanornis †Gansuidae? Changzuiornis Gansus Hollanda? Iteravis Khinganornis Shuilingornis Ornithurae †Antarcticavis? †Apatornis †Cerebavis †Gallornis †Guildavis †Iaceornis †Kookne †Limenavis †Tingmiatornis †Ichthyornithes Ichthyornis Janavis †Hesperornithes Baptornis Brodavis Chupkaornis Enaliornis Judinornis Pasquiaornis Potamornis Hesperornithidae Asiahesperornis Canadaga Fumicollis Hesperornis Parahesperornis †Vegaviidae Australornis? Maaqwi? Neogaeornis? Polarornis Vegavis †Cimolopterygidae Ceramornis Cimolopteryx Lamarqueavis? Aves / Neornithes see below↓
Aves / Neornithes Palaeognathae see Palaeognathae Neognathae Neoaves Galloanserae Anserimorphae see Anserimorphae Pangalliformes see Pangalliformes Incertae sedis †Asteriornis †Perplexicervix †Qinornis? †Dromornithidae Barawertornis Dromornis Genyornis Ilbandornis †Gastornithiformes Brontornis? Gastornis Dromornithidae? †Pelagornithidae Aequornis Caspiodontornis Cyphornis Dasornis Gigantornis Laornis? Lutetodontopteris Macrodontopteryx Manu? Odontopteryx Odontoptila Osteodontornis Palaeochenoides Pelagornis Proceriavis? Protodontopteryx Protopelicanus? Pseudodontornis Tympanonesiotes
See also: Archaeornithes Carinatae Deinonychosauria Odontognathae Odontornithes Sauriurae Unenlagiidae Category

• Pelagornithidae
• Eocene birds
• Eocene animals of Africa
• Prehistoric bird genera