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Wikipedia / Anseriformes

Anseriformes is an order of birds also known as waterfowl that comprises 178 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which includes the other 174 species of waterfowl, among them the ducks, geese, and swans. Most modern species in the order are highly adapted for an aquatic existence at the water surface. With the exception of screamers, males have penises, a trait that has been lost in the Neoaves, the clade consisting of all other modern birds except the galliformes and paleognaths. Due to their aquatic nature, most species are web-footed.

Evolution

Anseriformes are one of only two types of modern bird to be confirmed present during the Mesozoic alongside the other dinosaurs, and in fact were among the very few birds to survive their extinction, along with their cousins, the Galliformes. These two groups only occupied two ecological niches during the Mesozoic, living in water and on the ground, while the toothed Enantiornithes were the dominant birds that ruled the trees and air. The asteroid that ended the Mesozoic destroyed all trees as well as animals in the open, a condition that took centuries to recover from, with some models estimating that greenhouse effects lasted for thousands of years. The Anseriformes and Galliformes are thought to have survived in the cover of burrows and water, and not to have needed trees for food and reproduction.

The earliest known stem anseriform is the presbyornithid Teviornis from the Nemegt Formation of Mongolia. Some members apparently surviving the KT extinction event, including presbyornithids, thought to be the common ancestors of ducks, geese, swans, and screamers, the last group once thought to be Galliformes, but now genetically confirmed to be closely related to geese. The first known duck fossils start to appear about 34 million years ago.

Waterfowl are the best-known examples of sexually antagonistic genital coevolution in vertebrates, causing genital adaptations to coevolve in each sex to advance control over mating and fertilization. Sexually antagonistic coevolution (or SAC) occurs as a consequence of sexual conflict between males and females, resulting in coevolutionary process that reduce fit, or that functions to decrease ease of having sex.

Taxonomy

The Anseriformes and the Galliformes (pheasants, etc.) belong to a common group, the Galloanserae. They are the most primitive neognathous birds, and as such they should follow the Palaeognathae (ratites and tinamous) in bird classification systems. Several unusual extinct families of birds like the albatross-like pseudotooth birds and the giant flightless gastornithids and mihirungss have been found to be stem-anseriforms based on common features found in the skull region, beak physiology and pelvic region. The genus Vegavis for a while was found to be the earliest member of the anseriform crown group but a recent 2017 paper has found it to be just outside the crown group in the family Vegaviidae. However, the monophyly of Vegaviidae was questioned by Torres et al. (2025) who described a nearly complete skull of Vegavis in 2025, supporting its placement within crown group Anseriformes. However, Irazoqui et al. (2026) who redescribed this skull suggested that Vegavis can only be confidently placed as a neognath of uncertain affinities.

Below is the general consensus (prior to Torres et al. (2025)) of the phylogeny of anseriforms and their stem relatives.

Systematics

Anatidae is traditionally divided into subfamilies Anatinae and Anserinae. The systematics, especially regarding placement of some "odd" genera in the dabbling ducks or shelducks, is better resolved following the genetic analysis by Buckner et al. (2018); this has led to the reassignment of many genera to different tribes to which they were traditionally assigned. The list below follows the AviList, which has accepted these revisions: Note that AviList only includes extant and recently extinct genera:

Order Anseriformes

Suborder Anhimae Wetmore & Miller 1926

Family Anhimidae Stejneger 1885 (screamers)

  • Genus Anhima (Linnaeus 1766) Brisson 1760 (horned screamer)

  • Genus Chauna Illiger 1811

Suborder Anseres (true Anseriformes)

Family Anseranatidae Sclater 1880

  • Genus Anseranas (Latham 1798) Lesson 1828 (magpie goose)

Family Anatidae Leach 1820 (almost 150 species)

Subfamily Dendrocygninae Reichenbach 1849–50

Subfamily Stictonettinae

  • Genus Biziura Stephens 1824 (musk ducks)

  • Genus Nettapus von Brandt 1836 (pygmy geese)

  • Genus Stictonetta (Gould 1841) Reichenbach 1853 (freckled duck)

Subfamily Oxyurinae Swainson 1831 (stiff-tailed ducks and allies)

  • Genus Heteronetta (Merrem 1841) Salvadori 1865 (black-headed duck)

  • Genus Nomonyx (Linnaeus 1766) Ridgway 1880 (masked duck)

  • Genus Oxyura Bonaparte 1828

Subfamily Anserinae Vigors 1825 sensu Livezey 1996 (swans and geese)

Subfamily Anatinae Vigors 1825 sensu Livezey 1996

Tribe Tadornini Reichenbach 1849–50 (shelducks and sheldgeese)

Tribe Mergini Rafinesque 1815 (eiders, scoters, mergansers and other sea-ducks)

Tribe Aythyini Delacour and Mayr, 1945 (diving ducks)

  • Genus Sarkidiornis Eyton 1838

  • Genus Hymenolaimus (Gmelin 1789) Gray 1843 (blue duck)

  • Genus Chenonetta von Brandt 1836 (Australian wood duck)

  • Genus Cyanochen (Rüppell 1845) Bonaparte 1856 (blue-winged goose)

  • Genus Pteronetta (Cassin 1860) Salvadori 1895 (Hartlaub's duck)

  • Genus Marmaronetta (Ménétries 1832) Reichenbach 1853 (marbled duck)

  • Genus Asarcornis (Müller 1842) Salvadori 1895 (white-winged duck)

  • Genus ?†Rhodonessa Reichenbach 1853 (pink-headed duck)

  • Genus Netta Kaup 1829

  • Genus Aythya Boie 1822

Tribe Anatini Vigors 1825 sensu Livezey 1996 (dabbling ducks and moa-nalos)

  • Genus Salvadorina Rothschild & Hartert 1894 (Salvadori's teal)

  • Genus Lophonetta (King 1828) Riley 1914 (crested duck)

  • Genus Speculanas (King 1828) von Boetticher 1929 (bronze-winged duck)

  • Genus Amazonetta (Gmelin 1789) von Boetticher 1929 (Brazilian teal)

  • Genus Tachyeres Owen 1875 (steamer ducks)

  • Genus Sibirionetta (Georgi 1775) (Baikal teal)

  • Genus Spatula Boie 1822

  • Genus Mareca (Stephens 1824)

  • Genus Anas Linnaeus 1758

Extinct Anseriformes (fossil & subfossil)

Early basal Anseriformes:

  • ?†Conflicto Claudia P. Tambussi et al. 2019 tentatively placed here; possibly family Conflictonidae

  • †Anatalavis Olson & Parris 1987 (Late Cretaceous/Early Paleocene – Early Eocene) including Nettapterornis; may belong in Anseranatidae or Conflictonidae

  • †Naranbulagornis Zelenkov 2019

  • †Anachronornis

  • †Paakniwatavis Musser & Clarke 2024

Assigned to named families and subfamilies:

Family Anhimidae Stejneger 1885

Family Anseranatidae Sclater 1880

  • Genus †Anserpica Mourer-Chauviré, Berthet & Hugueney 2004

  • Genus †Eoanseranas Worthy & Scanlon 2009 (hand's dawn magpie goose)

Family †Presbyornithidae? Wetmore 1926 (wading-"geese")

Family †Paranyrocidae Miller & Compton 1939

  • Genus †Paranyroca Miller & Compton 1939 (Rosebud Early Miocene of Bennett County, USA)

Family Anatidae

Subfamily †Romainvilliinae Lambrecht 1933

Subfamily †Dendrocheninae Livezey & Martin 1988

Subfamily Oxyurinae Swainson 1831 (stiff-tailed ducks and allies)

Subfamily Anserinae Vigors 1825 sensu Livezey 1996 (swans and geese)

Tribe Tadornini Reichenbach 1849–50 (shelducks and sheldgeese)

Tribe Anatini Vigors 1825 (dabbling ducks and moa-nalos)

Unassigned extinct Anseriformes:

In addition, a considerable number of mainly Late Cretaceous and Paleogene fossils have been described where it is uncertain whether or not they are anseriforms. This is because almost all orders of aquatic birds living today either originated or underwent a major radiation during that time, making it hard to decide whether some waterbird-like bone belongs into this family or is the product of parallel evolution in a different lineage due to adaptive pressures.

  • "Presbyornithidae" gen. et sp. indet. (Barun Goyot Late Cretaceous of Udan Sayr, Mongolia) – Presbyornithidae?

  • UCMP 117599 (Hell Creek Late Cretaceous of Bug Creek West, USA)

  • Petropluvialis (Late Eocene of England) – may be same as Palaeopapia

  • Agnopterus (Late Eocene – Late Oligocene of Europe) – includes Cygnopterus lambrechti

  • "Headonornis hantoniensis" BMNH PAL 4989 (Hampstead Early Oligocene of Isle of Wight, England) – formerly "Ptenornis"

  • Palaeopapia (Hampstead Early Oligocene of Isle of Wight, England)

  • "Anas" creccoides (Early/Middle Oligocene of Belgium)

  • "Anas" skalicensis (Early Miocene of "Skalitz", Czech Republic)

  • "Anas" risgoviensis (Late Miocene of Bavaria, Germany)

  • †"Anas" meyerii Milne-Edwards 1867 [Aythya meyerii (Milne-Edwards 1867) Brodkorb 1964]

  • †Eonessa anaticula Wetmore 1938 {Eonessinae Wetmore 1938}

Molecular studies

Studies of the mitochondrial DNA suggest the existence of four branches – Anseranatidae, Dendrocygninae, Anserinae and Anatinae – with Dendrocygninae being a subfamily within the family Anatidae and Anseranatidae representing an independent family. The clade Somaterini has a single genus Somateria.

See also

References

Cited texts

  • Murray, P. F. & Vickers-Rich, P. (2004) Magnificent Mihirungs: The Colossal Flightless Birds of the Australian Dreamtime. Indiana University Press.