Eutreptornis ("changing bird")is a genus of

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 ...

possible cariamiforme bird from the Late

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 ...

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

. It is traditionally considered to be a bathornithid, though a combination of the relative incompleteness of the material alongside some differences from other bathornithids have raised some suspicions about this affiliation.

Description

''Eutreptornis'' is currently represented by a single type species, ''E. uintae'', in turn represented by a

tibiotarsus The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These ...

and

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...

from the

Uinta Formation The Uinta Formation is a geologic formation in northeastern Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Ariz ...

Biology

It is represented by the smallest bathornithid remains known. Due to the incompleteness of its remains it is unclear whereas it was flightless like other bathornithids. It was, however, most certainly a terrestrial predator, perhaps akin to its closest living relatives, the seriemas.

Ecology

''Eutreptornis'' co-existed with a rich mammalian

megafauna In zoology, megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and Neo-Latin ''fauna'' "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately , this lower en ...

, such as the

brontothere Brontotheriidae is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs. Superficially, they looked rather like rhinos with some developing bony nose horns, and were some of ...

Megacerops ''Megacerops'' ("large-horned face", from '' méga-'' "large" + '' kéras'' "horn" + '' ōps'' "face") is an extinct genus of the prehistoric odd-toed ungulate (hoofed mammal) family Brontotheriidae, an extinct group of rhinoceros-like browsers ...

'', as well as other terrestrial birds, including other bathornithid birds such as the larger ''

Bathornis ''Bathornis'' ("tall bird") is an extinct genus of birds related to modern day seriemas, that lived in North America about 37–20 million years ago. Like the closely related and also extinct phorusrhacids, it was a flightless predator, occupying ...

'' species and the flightless crane-like geranoidids.Joel Cracraft, Systematics and evolution of the Gruiformes (Class Aves). 2, Additional comments on the Bathornithidae, with descriptions of new species. ''American Museum Novitates''; no. 2449

References

{{Taxonbar, from=Q25095786 Bathornitidae Eocene birds Bird genera Paleogene birds of North America Taxa named by Joel Cracraft