Common loon Gavia immer, copyright Gary Irwin.

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 Gaviiformes, 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.

<==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 1891M05
| | |--C. belgicus Mayr & Smith 2002M09
| | `--C. metzleri Mayr 2004M05
| `--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)
| |--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
| |--SulidaPB15
| `--FregatidaeM09
| |--FregataPB15
| `--LimnofregataM09
| |--L. azygosternon Olson 1977M09
| `--L. hasegawai Olson & Matsuoka 2005M09
| |--ArdeidaePB15
| `--Xenerodiops [Xenerodiopidae]U93
| `--X. mycter Rasmussen et al. 1987M09
`--+--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


[B94] Bock, W. J. 1994. History and nomenclature of avian family-group names. Bulletin of the American Museum of Natural History 222: 1–281.

[B93] Brooke, R. K. 1993. Annotated catalogue of the Aves type specimens in the South African Museum. Annals of the South African Museum 102 (10): 327–349.

[C02] Chatterjee, S. 2002. The morphology and systematics of Polarornis, a Cretaceous loon (Aves: Gaviidae) from Antarctica. In: Zhou, Z., & F. Zhang (eds) Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution. Beijing, 1–4 June 2000 pp. 125–155. Science Press: Beijing.

[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.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[FP64] Fisher, J., & R. T. Peterson. 1964. The World of Birds: A comprehensive guide to general ornithology. Macdonald: London.

[JT12] Jetz, W., G. H. Thomas, J. B. Joy, K. Hartmann & A. Ø. Mooers. 2012. The global diversity of birds in space and time. Nature 491: 444–448.

[KF-V21] Kuhl, H., C. Frankl-Vilches, A. Bakker, G. Mayr, G. Nikolaus, S. T. Boerno, S. Klages, B. Timmermann & M. Gahr. 2021. An unbiased molecular approach using 3′-UTRs resolves the avian family-level tree of life. Molecular Biology and Evolution 38 (1): 108–127.

[M04] Mayr, G. 2004. Tertiary plotopterids (Aves, Plotopteridae) and a novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae). Journal of Zoological Systematics and Evolutionary Research 43: 61–71.

[M05] Mayr, G. 2005. The Paleogene fossil record of birds in Europe. Biological Reviews 80: 515–542.

[M09] Mayr, G. 2009. Paleogene Fossil Birds. Springer.

[M02] Mlíkovský, J. 2002. Cenozoic Birds of the World. Part 1: Europe. Ninox Press: Praha.

[OF80] Olson, S. L., & A. Feduccia. 1980. Relationships and evolution of flamingos (Aves: Phoenicopteridae). Smithsonian Contributions to Zoology 316: 1–73.

[PB15] Prum, R. O., J. S. Berv, A. Dornburg, D. J. Field, J. P. Townsend, E. M. Lemmon & A. R. Lemmon. 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature 526: 569–573.

[S05] Schalow, H. 1905. Die Vögel der Arktis. In: Römer, F., & F. Schaudinn (eds) Fauna Arctica. Eine Zusammenstellun der arktischen Tierformen, mit besonder Berücksichtigung des Spitzbergen-Gebietes auf Grund der Ergebnisse der Deutschen Expedition in das Nördliche Eismeer im Jahre 1898 vol. 4 pp. 79–288. Gustav Fischer: Jena.

[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.

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