Presbyornis

Taxobox
name = "Presbyornis"
status = fossil
fossil_range = Late Paleocene -? Early Oligocene
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Anseriformes
familia = Presbyornithidae
genus = "Presbyornis"
genus_authority = Wetmore, 1926
subdivision_ranks = Species
subdivision = "Presbyornis isoni" Olson, 1994"Presbyornis pervetus" Wetmore, 1926; type species
"Presbyornis recurvirostris" (Hardy, 1959; disputed)

synonyms = "Nautilornis" Wetmore, 1926
"Coltonia" Hardy, 1959 "Presbyornis" is an extinct genus of anseriform bird. It contains two unequivocally accepted species, the well-known "P. pervetus" and the much lesser-known "P. isoni". "P. pervetus" was approximately the size and shape of a goose, but with longer legs; "P. isoni", known from a few bones, was much larger, more than swan-sized. Other fossils, more doubtfully assigned to this genus, are also known.

The fossil record of "P. pervetus" includes many complete skeletons from Green River Formation sites (Early Eocene), suggesting that the birds nested in colonies and possibly were liable to succumb to botulism, similar to many colony-nesting waterfowl or shorebirds today. "P. isoni" is known from the Late Paleocene Aquia Formation (Maryland, 61-62 MYA) humerus (USNM 294116) and a fingerbone (USNM 294117) that were initially described, as well as from the humeri that were initially believed to be from "Headonornis" (BMNH PAL 3686, 5105, 6240). As these are Late Eocene or even Early Oligocene (BMNH PAL 5105, Bembridge Marls) in age, they possibly belong to a distinct taxon. "P. recurvirostris" is a disputed species possibly synonymous with "P. pervetus"; it is known from a partial wing (KUVP 10105) found in Colton Formation Eocene sediments of the Wasatch Plateau near Ephraim, Utah. Undescribed fossils are also known from the Paleocene of Utah and possibly the Early Eocene of Mongolia [Kurochkin "et al" (2002)] . The coracoid still assigned to "Headonornis" [Dyke (2001)] may also belong into this genus.

"Presbyornis" was one of the first anseriforms. Because of its long legs and neck, "Presbyornis" was initially mistaken for a flamingo, but it was reclassified as an anseriform when the duck-like anatomy of its skull and bill was found. Later, it was believed to represent a transitional stage between the anseriforms and the shorebirds, but it is now considered a member of an extinct group of anseriforms which was most closely related to ducks and geese. Judging from numerous fossil findings, "Presbyornis" is presumed to have lived in colonies around shallow lakes. Its broad, flat bill was used to filter food (small plants and animals) from the water, in the manner of today's dabbling ducks.

Footnotes

References

* (2001): The Fossil Waterfowl (Aves: Anseriformes) from the Eocene of England. "American Museum Novitates" 3354: 1-15. [http://digitallibrary.amnh.org/dspace/bitstream/2246/2907/1/N3354.pdf PDF fulltext]
* (2002): A New Presbyornithid Bird (Aves, Anseriformes) from the Late Cretaceous of Southern Mongolia. "American Museum Novitates" 3386: 1-11. [http://digitallibrary.amnh.org/dspace/bitstream/2246/2875/1/N3386.pdf PDF fulltext]
* (1926): Fossil birds from the Green River Deposits of Easter Utah. "Annals of the Carnegie Museum" 16: 391-402.

External links

* [http://critters.pixel-shack.com/WebImages/crittersgallery/Presbyornis.jpgReconstruction of "Presbyornis" at critters.pixel-shack.com]