Presbyornis

Presbyornis is an extinct genus of presbyornithid bird from North America during the Paleogene period, between the Late Paleocene and Early Eocene.

==History of discovery== thumb|left|Life restoration of P. pervetus 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 that they possibly died due to volcanism or botulism, the latter of which is similar to many colony-nesting waterfowl or shorebirds today. Fossils identified as P. cf. pervetus have been discovered from the Margaret Formation of Ellesmere Island, where the remains of Gastornis sp. have also been found.