Presbyornithids
| Presbyornithids Temporal range: Late Cretaceous – Miocene. 71–15 Ma |
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| The specialised, territorial Wilaru attacking the mysterious mammal Yingabalanara. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Anseriformes |
| Family: |
†Presbyornithidae Wetmore, 1926 |
| Genera | |
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Presbyornithidae is an extinct group of birds with a global distribution. They had evolved by the late Cretaceous period and became extinct during the early Miocene. 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, but they are now generally accepted to be waterfowl closely related to modern ducks, geese, and screamers.
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. At least some species were social birds that lived in large flocks and nested in colonies, while others, like the Wilaru species, were terrestrial and solitary.
As the "wading duck" moniker implies, they were waterfowl whose elongated legs enabled them to live a lifestyle similar to the "proto-flamingos" (e.g., Palaelodus) – which were not really ancestors of the modern flamingos, but a group that evolved in parallel with them and in fact seems to have taken over part of the presbyornithid's ecological niche after the latter became extinct. Thus, while probably somewhat capable of swimming, they would have preferred to strain the shallow waters of their habitat for food and were also able to snatch up insects and small crustaceans on dry land, just like some species of modern ducks, e.g., the Laysan duck, hunt for brine flies.
The implication of the plethora of this and other, ecologically similar Neornithes (e.g., the wastebasket taxon "Graculavidae") from the Late Cretaceous and early Palaeogene is that shore habitats offered most resources for ancestors of modern birds. The reasons seem to have been that arboreal niches were where the main radiation of the Enantiornithes had taken place some time earlier, and later on because the Cretaceous–Paleogene mass extinction affected both aquatic and terrestrial habitats extensively, leading to the almost total collapse of their trophic webs. In marine habitats, the climatic changes associated with the mass extinction's cause(s) caused a wholesale die-off of oceanic phytoplankton and thus their food webs were destroyed from the bottom up. In terrestrial habitats on the other hand, apart from the loss of the primary production capacity, the keystone species, which were in almost all cases dinosaurs, disappeared, leading the trophic webs on dry land to collapse also from the inside out.
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Wikipedia