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
The fossil record of P. pervetus includes many complete skeletons from Green River Formation sites, 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.P. recurvirostra is known from a partial wing found in the Colton Formation, from the Late Paleocene to Early Eocene sediments of the Wasatch Plateau near Ephraim, Utah. P. isoni, much larger than P. pervetus, is known from the Late Paleocene Aquia Formation in Maryland, based on the partial humerus and partial fingerbone that were initially described, as well as a complete humerus. Three humeri that were initially believed to be from Headonornis are suggested to belong to P. isoni, and the holotype coracoid of Headonornis may also be assigned to as P. isoni, though these claims require additional material for confirmation. However, Headonornis is now referred to as a stem group representative of the Phoenicopteriformes.
The holotype and paratypes of "P." mongoliensis are known from the Early Eocene of Mongolia, but these fragmentary specimens are poorly preserved and they likely belong to a stem Phoenicopterimorphae, not a presbyornithid. Undescribed fossils are also known from the Paleocene of Utah. Wunketru howardae, previously thought to be a species of Telmabates or a junior synonym of P. pervetus, is now considered a distinct anseriform.