High Quality Content by WIKIPEDIA articles! Presbyornithidae were a family of waterbirds with an apparently global distribution that lived until the Earliest Oligocene, but are now extinct. Initially, they were believed to present a mix of characters shown by waterbirds, shorebirds and flamingos and were used to argue for an evolutionary relationship between these groups (Feduccia 1976), but they are now generally accepted to be "wading ducks", the sister taxon of the Anatidae, and thus essentially modern waterbirds. They were generally long-legged, long-necked birds, standing around one meter high, with the body of a duck, feet similar to a wader but webbed, and a flat duck-like bill adapted for filter feeding. Apparently, at least some species were very social birds that lived in large flocks and nested in colonies.