''Eocypselus rowei'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

bird believed to be ancestral to modern

hummingbird Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With about 361 species and 113 genera, they occur from Alaska to Tierra del Fuego, but the vast majority of the species are found in the tropics aro ...

s and swifts. It was a small bird, less than in length, and probably had black feathers. The bird was first described in 2013 and lived approximately 50 million years ago, during the Eocene epoch.

Discovery and classification

''Eocypselus rowei'' was first described in 2013 by Daniel T. Ksepka, Julia A. Clarke,

Sterling J. Nesbitt Sterling Nesbitt (born March 25, 1982, in Mesa, Arizona) is an American paleontologist best known for his work on the origin and early evolutionary patterns of archosaurs. He is currently an associate professor at Virginia Tech in the Department ...

, Felicia B. Kulp, and

Lance Grande Roger Lansing Grande (born February 16, 1951), more commonly known as Lance Grande, is an evolutionary biologist and curatorial scientist. His research and work is focused on Paleontology, Ichthyology, Systematics and Evolution. He is best known fo ...

in the Proceedings of the Royal Society B: Biological Sciences. The researchers spotted an exceptionally preserved specimen, originally harvested from the Green River Formation of Wyoming, while working at Chicago's

Field Museum of Natural History The Field Museum of Natural History (FMNH), also known as The Field Museum, is a natural history museum in Chicago, Illinois, and is one of the largest such museums in the world. The museum is popular for the size and quality of its educational ...

. The specimen includes well preserved feathers and a nearly complete skeleton. It contains fossilized melanosomes, pigmentation cell structures. They named the new species in honor of John Rowe, Chairman of the Field Museum's Board of Trustees. The discoverers chose to honor Rowe, whom they considered to be a "fossil geek." According to its discoverers, ''E. rowei'' is a basal form of the order Apodiformes, which traditionally includes

tree swift Treeswifts or crested swifts are a family, the Hemiprocnidae, of aerial near passerine birds, closely related to the true swifts. The family contains a single genus, ''Hemiprocne'', with four species. They are distributed from India and Southeast ...

s, and swifts. Earlier authors reached the same conclusions based on European fossils of ''Eocypselus''.Mayr, G. (2010)
Reappraisal of ''Eocypselus'' – a stem group representative of apodiform birds from the early Eocene of Northern Europe
Palaeobiodiversity and Palaeoenvironments, 90: 395-403.

Description

''Eocypselus rowei'' shares features in common with both hummingbirds and swifts leading Ksepka to declare "This fossil bird represents the closest we've gotten to the point where swifts and hummingbirds went their separate ways". It was probably not a hoverer, like a hummingbird, but also not a fast flyer like a swift. ''E. rowei'' was less than from head to tail. Its feathers made up more than half the size of its wingspan. The bird was small enough to fit into the palm of a hand and weighed less than . It probably had black plumage and may have had an iridescent sheen, like modern swifts. ''Eocypselus rowei'' lived approximately 50 million years ago, during the Eocene epoch. It was probably an

insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

References

{{Taxonbar, from=Q15290307 Cypselomorphae Eocene birds Extinct birds of North America Extinct animals of the United States Fossil taxa described in 2013 Paleogene birds of North America Taxa named by Sterling Nesbitt