Gastornis

Gastornis is an extinct genus of large, flightless birds that lived from the middle Paleocene to the middle Eocene epochs of the Paleogene. Most known fossils have been recovered from Europe, although species historically assigned to the genus have also been reported from North America and Asia. Several genera, including the well-studied Diatryma, have traditionally been regarded as junior synonyms of Gastornis. This classification has been challenged by more recent studies, however, and some researchers regard Diatryma as a distinct and valid genus. Gastornis species were very large birds historically considered to be predators of small mammals, including early, diminutive equids. This interpretation has since been questioned by several lines of evidence. The absence of hooked claws in known Gastornis footprints, together with analyses of its beak morphology and the isotopic signatures of its bones, suggests that it was more likely herbivorous, feeding primarily on tough plant material and seeds. Gastornis is generally considered to be related to the Galloanserae, the clade comprising modern waterfowl and gamebirds.