Editing Anseriformes (section)

==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{{citation needed|reason=Centuries? This sounds way too short. An unimpeachable citation of the actual span is needed.|date=November 2022}} 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.<ref>[https://www.science.org/content/article/quaillike-creature-was-only-bird-survive-dinosaur-killing-asteroid-impact Quail-like creatures were the only birds to survive the dinosaur-killing asteroid impact]</ref>

The earliest known stem anseriform is the [[presbyornithid]] ''[[Teviornis]]'' from the [[Nemegt Formation]] of [[Mongolia]].<ref name=M2021>{{cite journal|last1=Marjanović|first1=D.|year=2021|title=The Making of Calibration Sausage Exemplified by Recalibrating the Transcriptomic Timetree of Jawed Vertebrates|journal=Frontiers in Genetics|volume=12|at=521693|doi=10.3389/fgene.2021.521693|doi-access=free |pmid=34054911 |pmc=8149952}}</ref> Some members apparently surviving the [[KT extinction event]], including [[presbyornithid]]s, thought to be the common ancestors of ducks, geese, swans, and [[screamer]]s, 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.<ref>{{Cite journal|last1=Brennan|first1=Patricia L.R.|last2=Prum|first2=Richard O.|date=July 2015|title=Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection, Mate Choice, and Sexual Conflict|journal=Cold Spring Harbor Perspectives in Biology|volume=7|issue=7|pages=a017749|doi=10.1101/cshperspect.a017749|pmid=26134314|pmc=4484975|issn=1943-0264}}</ref>