Systematics and Evolution
From the limited fossils that have to date been recovered, the conclusion that they were already widespread—the predominant group of modern birds—by end of the Cretaceous is generally accepted nowadays. Fossils such as Vegavis indicate that essentially modern waterfowl, albeit belonging to a nowadays extinct lineage, were contemporaries of the (non-avian) dinosaurs. As opposed to the morphologically fairly conservative Galliformes, the Anseriformes have adapted to filter-feeding and are characterized by a large number of autapomorphies related to this lifestyle. The extremely advanced feeding systems of the Anseriformes, together with similarities of the early anseriform Presbyornis to shorebirds, had formerly prompted some scientists to ally Anseriformes with Charadriiformes instead. However, as strong support for the Galloanserae has emerged in subsequent studies, the fowl clade continues to be accepted as a genuine evolutionary lineage by the vast majority of scientists.
Apart from the living members, the Gastornithidae are probably a prehistoric member of the Galloanserae.
Read more about this topic: Fowl
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—Owen Barfield (b. 1898)