White Swan Aquatick Ambience BIRD
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which includes over 170 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. Due to their aquatic nature, most species are web-footed.
Anseriformes
Temporal range: Paleocene–Present
PreꞒꞒOSDCPTJKPgN
Stem groups present since Maastrichtian[1]
Magpie goose, Anseranas semipalmata
Scientific classificationEdit this classification
Domain:
Eukaryota
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Clade:
Anserimorphae
Order:
Anseriformes
Wagler, 1831
Extant families
Anhimidae
Anseranatidae
Anatidae
†Dromornithidae
Range of the waterfowl and allies
Evolution
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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[citation needed] to recover from. 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.[2]
The earliest known stem anseriform is the presbyornithid Teviornis from the Nemegt Formation of Mongolia.[3] 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.[4]