Eutreptornis

Eutreptornis Temporal range: Late Eocene
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Cariamiformes (?)
Family:	†Bathornithidae (?)
Genus:	†Eutreptornis Cracraft, 1971
Species:	†E. uintae
Binomial name
†Eutreptornis uintae (Cracraft, 1971)

Eutreptornis ("changing bird"^[1])is a genus of extinct possible cariamiforme bird from the Late Eocene of Utah. It is traditionally considered to be a bathornithid,^[2][3] though a combination of the relative incompleteness of the material alongside some differences from other bathornithids have raised some suspicions about this affiliation.^[4][5]

Eutreptornis is currently represented by a single type species, E. uintae, in turn represented by a tibiotarsus and tarsometatarsus from the Uinta Formation of Utah.

It is represented by the smallest bathornithid remains known.^[6] 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.

Eutreptornis co-existed with a rich mammalian megafauna, such as the brontothere Megacerops, as well as other terrestrial birds, including other bathornithid birds such as the larger Bathornis species and the flightless crane-like geranoidids.^[7]