page_title: Gastornis
section_title: Feathers
hierarchical_section_title: Gastornis / Paleobiology / Feathers
caption_attribution_description: English: Drawing of a very large feather from the Green River Formation, probably referrable to Gastornis
context_page_description: Gastornis is an extinct genus of large flightless birds that lived during the late Paleocene and Eocene epochs of the Cenozoic era. The genus is currently thought to contain three or four distinct species, known from incomplete fossil remains, found in western-central Europe. More complete specimens are known from a fourth, North American species, which had previously been classified in the distinct genus Diatryma. Many scientists now consider Diatryma to be so similar to the other species of Gastornis that it should also be included in that genus. A fifth species, also previously classified in its own genus, is known from China.
  Gastornis species were very large birds, and have traditionally been considered to be predators of small mammals. However, several lines of evidence, including the lack of hooked claws in known Gastornis footprints and studies of their beak structure have caused scientists to reinterpret these birds as herbivores that probably fed on tough plant material and seeds.
context_section_description: The plumage of Gastornis has generally been depicted in art as a hair-like covering similar to some ratites. This has been based in part on some fibrous strands recovered from a Green River Formation deposit at Roan Creek, Colorado, which were initially believed to represent Gastornis feathers and named Diatryma filifera. Subsequent examination has shown the supposed feathers were actually not feathers at all, but plant fibers.
  However, a second possible Gastornis feather has since been identified, also from the Green River Formation. Unlike the filamentous plant material, this single isolated feather resembles the body feathers of flighted birds, being broad and vaned. It was tentatively identified as a possible Gastornis feather based on its size; the feather measured 240 mm (9.4 in) long and must have belonged to a gigantic bird.
caption: Drawing of probable Gastornis feather from the Green River Formation. By Darren Naish
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