Bathornithidae is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

family of birds from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. Part of Cariamiformes, they are related to the still extant seriemas and the extinct Phorusrhacidae. They were likely similar in habits, being terrestrial, long-legged predators, some of which attained massive sizes. It has been suggested that most, if not all, North American

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

cariamiforme fossils are part of this group. Storrs Olson also referred the European '' Elaphrocnemus'' to this clade, though it has since been rejected. Conversely, some analysis have instead recovered them as a

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

group, with '' Bathornis'' and kin being sister taxa to phorusrhacids while '' Paracrax'' is rendered closer to modern seriemas, though this assessment is heavily debated. The most recent consensus is that Bathornithidae is relegated exclusively to '' Bathornis'', as a clade of Cariamiformes outside of a clade including seriemas and phorusrhacids, as well as a possible European specimen. '' Paracrax'' and '' Eutreptornis'' are understood to be odd taxa whose cariamiform affinities are not fully resolved. A 2024 study however finds ''Bathornis'' as closer to seriemas than phorusrhacids were.

Biology

Though some forms like '' Paracrax wetmorei'' might have been capable of flight, most taxa were flightless, constituting examples of flightless birds in mammal dominated environments. ''Paracrax gigantea'', ''Paracrax antiqua'' and the larger '' Bathornis'' species in particular might have occupied macropredatory niches akin to that of phorusrhacids, the former and latter reaching heights of over '' Bathornis'' proper appears to have favoured wetland environments. It was a highly diverse genus, spanning a wide variety of species at various sizes, from the

to the

References

{{Taxonbar, from=Q21292506 Eocene birds Miocene birds Oligocene birds Bird genera Paleogene birds of North America Extinct flightless birds Miocene birds of North America White River Fauna Taxa named by Joel Cracraft Prehistoric bird families