Belongs within: Neognathae.
Contains: Procellariiformes, Spheniscidae, Ciconiidae, Sulida, Fregata, Threskiornithidae, Ardeidae, Pelecanidae.
The Aequornithia are a clade of birds united by molecular phylogenetic analysis, commonly referred to as the ‘higher water-birds’. Most species are associated with aquatic habitats, from open ocean to terrestrial wetlands. Members of the clade include the Gaviidae, divers or loons, a group of streamlined birds with the feet placed far back on the body, making them powerful swimmers but rather poor walkers. The Late Cretaceous fossils Polarornis gregorii and Neogaeornis wetzeli have been identified as potential early gaviids (Mayr 2009).
Aequornithia [Natatores]PB15
|--Gaviidae [Colymbidae, Colymboididae, Eudytidae, Gaviiformes, Gaviimorphae, Urinatoridae]KF-V21
| |--Gaviella pusilla (Shufeldt 1915)M09
| |--Neogaeornis wetzeli Lambrecht 1929C02, M09
| |--Eupterornis Lemoine 1878FP64, M02
| | `--*E. remensis Lemoine 1878M02
| |--Polarornis Chatterjee 2002C02
| | `--*P. gregorii Chatterjee 2002C02
| |--Colymboides Milne-Edwards 1867 (see below for synonymy)M02
| | |--*C. minutus Milne-Edwards 1867 [incl. *Hydrornis natator Milne-Edwards 1867, *Dyspetornis natator]M02
| | |--C. anglicus Lydekker 1891M09
| | |--C. belgicus Mayr & Smith 2002M09
| | `--C. metzleri Mayr 2004M09
| `--Gavia Forster 1788M02 (see below for synonymy)
| | i. s.: ‘Colymbus’ calipareusS05
| | ‘Colymbus’ capensisK08
| | G. concinnaM02
| | ‘Colymbus’ dominicusS18
| | |--C. d. dominicusS18
| | `--C. d. brachyrhynchusS18
| | G. egeriana Švec 1982M02
| | G. lumme (Gunn. 1761) (see below for synonymy)S05
| | G. moldavica Kessler 1984M02
| | G. paradoxa Umans’ka 1981M02
| | G. portisi (Regàlia 1902) [=Colymbus portisi]M02
| | G. schultzi Mlíkovský 1998M02
| |--G. stellata (Pontoppidan 1763)JT12, CS77 [=Colymbus stellatusCS77]
| `--+--G. arctica (Linnaeus 1758)JT12, CS77 [=Colymbus arcticusCS77, Podiceps arcticusS05, Urinator arcticusS05]
| | |--G. a. arcticaCS77
| | `--G. a. viridigularis Dwight 1918CS77
| `--+--G. pacifica (Lawrence 1858)JT12, CS77 (see below for synonymy)
| `--+--*G. immer (Brünnich 1764)B94, JT12, B94 (see below for synonymy)
| `--G. adamsii (Gray 1859)JT12, CS77 (see below for synonymy)
`--+--ProcellariimorphaePB15
| |--ProcellariiformesPB15
| `--+--SpheniscidaePB15
| `--PlotopteridaeM04
| | i. s.: Hokkaidornis abashiriensis Sakurai et al. 2008M09
| |--Phocavis maritimus Goedert 1988M09
| `--+--Tonsala hildegardae Olson 1980M09
| `--Copepteryx Olson & Hasegawa 1996M09, D07
| |--C. hexeris Olson & Hasegawa 1996M09
| `--C. titan Olson & Hasegawa 1996M09
`--Pelecanimorphae [Herodiones, Pelargi, Pelecanides, Steganograllatores, Steganopodes]PB15
| i. s.: Novacaesareala hungerfordi Parris & Hope 2002M09
| TorotigidaeFP64
| |--Gallornis straeleni Lambrecht 1931FP64, OF80
| `--Torotix Brodkorb 1963OF80
| `--*T. clemensi Brodkorb 1963OF80
|--CiconiidaePB15
`--+--SuliformesJT12
| |--SulidaPB15
| `--FregatidaeM09
| |--FregataPB15
| `--LimnofregataM09
| |--L. azygosternon Olson 1977M09
| `--L. hasegawai Olson & Matsuoka 2005M09
`--PelecaniformesKF-V21
|--ThreskiornithidaePB15
`--+--ArdeiformesU93
| |--ArdeidaePB15
| `--Xenerodiops [Xenerodiopidae]U93
| `--X. mycter Rasmussen et al. 1987M09
`--+--PelecanidaeKF-V21
`--+--Scopus Brisson 1760KF-V21, B94 [Scopi, Scopidae, Scopoidea]
| |--S. umbrettaPB15
| `--S. xenopus Olson 1984B93
`--Balaenicipitidae [Balaenicipites, Balaenicipitiformes]KF-V21
|--Goliathia andrewsi Lambrecht 1930M09
`--Balaeniceps Gould 1850B94
`--B. rexPB15
Colymboides Milne-Edwards 1867 [incl. Dyspetornis Oberholser 1905, Hydrornis Milne-Edwards 1867 non Blyth 1843]M02
Gavia Forster 1788M02 [=Colymbus Linnaeus 1758 (nom. rej.)B94; incl. Eudytes Illiger 1811B94, Mergus Brisson 1860 non Linnaeus 1758B94, Urinator Lacépède 1799B94]
Gavia adamsii (Gray 1859)JT12, CS77 [=Colymbus adamsiiCS77, C. glacialis var. adamsiiS05, Urinator adamsiS05]
*Gavia immer (Brünnich 1764)B94, JT12, B94 [=*Colymbus immerB94, Urinator imberS05; incl. C. torquatus Kumlien 1897S05, C. glacialis typicus Winge 1898S05]
Gavia lumme (Gunn. 1761) [=Colymbus lumme, Urinator lumme; incl. C. glacialis Phipps 1774, C. septentrionalis Fabricius 1780, Urinator septentrionalis]S05
Gavia pacifica (Lawrence 1858)JT12, CS77 [=Colymbus pacificusS05, C. arcticus var. pacificusS05, Gavia arctica pacificaCS77, Urinator pacificusS05]
*Type species of generic name indicated
References
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[CS77] Cramp, S., & K. E. L. Simmons (eds) 1977. Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palaearctic vol. 1. Ostrich to Ducks. Oxford University Press: Oxford.
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[M09] Mayr, G. 2009. Paleogene Fossil Birds. Springer.
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[S18] Stone, W. 1918. Birds of the Panama Canal Zone, with special reference to a collection made by Mr. Lindsey L. Jewel. Proceedings of the Academy of Natural Sciences of Philadelphia 70: 239–280.
[U93] Unwin, D. M. 1993. Aves. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 717–737. Chapman & Hall: London.