Bathornithidae is an extinct family of birds from the

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

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 ...

of North America. Part of Cariamiformes, they are related to the still extant

seriemas The seriemas are the sole living members of the small bird family Cariamidae, which is also the only surviving lineage of the order Cariamiformes. Once believed to be related to cranes, they have been placed near the falcons, parrots and passer ...

and the also extinct

Phorusrhacidae Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...

. 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 cariamiforme fossils are part of this group.

Storrs Olson Storrs Lovejoy Olson (April 3, 1944 – January 20, 2021) was an American biologist and ornithologist who spent his career at the Smithsonian Institution, retiring in 2008. One of the world's foremost avian paleontologists, he was best known ...

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 of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

group, with '' Bathornis'' and kin being sister taxa to phorusrhacids while ''

Paracrax ''Paracrax'' ("near curassow") is a genus of extinct North American flightless birds, possibly related to modern seriemas and the extinct terror birds. Part of Bathornithidae (though some analysis recover it as closer to the living seriemas in ...

'' is rendered closer to modern seriemas, though this assessment is heavily debated.Mayr, G., & Noriega, J. I. A well-preserved partial skeleton of the poorly known early Miocene seriema ''Noriegavis santacrucensis'' (Aves, Cariamidae). ''Acta palaeontologica Polonica'', 60(3):589-598. The most recent consensus is that Bathornithidae is relegated exclusively to '' Bathornis'', as a clade of Cariamiformes outside of a clade including seriemas and

phorusrhacid Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...

s, as well as a possible European specimen. ''

'' and '' Eutreptornis'' are understood to be odd taxa whose cariamiform affinities are not fully resolved.

Biology

Though some forms like ''

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