A tale of two wings: The feathered fossil that reveals the swift and the hummingbird are closely related
- Offers clues to the precursors of swift and hummingbird wings
- 12cm long bird weighed less than an ounce
By Mark Prigg
PUBLISHED: 1 May 2013
A tiny bird fossil discovered in Wyoming has revealed just how the swing and the hummingbird evolved.
Researchers spotted the specimen, a nearly complete skeleton of a bird that would have fit in the palm of the hand and weighed less than an ounce, while working at the Field Museum of Natural History in Chicago.
The analysis found the bird gives a new insight into precursors of swift and hummingbird wings.
12cm from head to tail, E. rowei was an evolutionary precursor to the group that includes today's swifts and hummingbirds, researchers
AN UNLIKELY FAMILY
Researchers have long puzzled over the birds, which have very different wing shapes, yet come from the same family.
Hummingbirds have short wings relative to their bodies, which makes them good at hovering in mid-air.
Swifts have super-long wings for gliding and high-speed flight.
But the wings of E. rowei were somewhere in between.
The fossil is unusual in having exceptionally well-preserved feathers, which allowed the researchers to reconstruct the size and shape of the bird's wings in ways not possible with bones alone.
The newly discovered bird was named Eocypselus rowei, in honor of John W. Rowe, Chairman of the Field Museum's Board of Trustees.
First collected in southwestern Wyoming in a fossil site known as the Green River Formation, E. rowei lived roughly 50 million years ago, after the dinosaurs disappeared but before the earliest humans came to be.
The researchers say it was a tiny bird - only twelve centimeters from head to tail.
Feathers account for more than half of the bird's total wing length.
Swifts have super-long wings for gliding and high-speed flight
To find out where the fossil fit in the bird family tree, the researchers compared the specimen to extinct and modern day species, and found it was an evolutionary precursor to the group that includes today's swifts and hummingbirds.
Researchers have long puzzled over the birds, which have very different wing shapes.
'This fossil bird represents the closest we've gotten to the point where swifts and hummingbirds went their separate ways,' said Daniel Ksepka of the National Evolutionary Synthesis Center in Durham, North Carolin, who led the research.
Hummingbirds have short wings relative to their bodies, which makes them good at hovering in mid-air.
Swifts have super-long wings for gliding and high-speed flight.
But the wings of E. rowei were somewhere in between, the researchers found.
A Ruby Throated Hummingbird, Hummingbirds have short wings relative to their bodies, which makes them good at hovering in mid-air
'[Based on its wing shape] it probably wasn't a hoverer, like a hummingbird, and it probably wasn't as efficient at fast flight as a swift,' Ksepka said.
The shape of the bird's wings, coupled with its tiny size, suggest that the ancestors of today's swifts and hummingbirds got small before each group's unique flight behavior came to be.
'Hummingbirds came from small-bodied ancestors, but the ability to hover didn't come to be until later,' Ksepka explained.
Closer study of the feathers under a scanning electron microscope revealed that carbon residues in the fossils — once thought to be traces of bacteria that fed on feathers — are fossilized melanosomes, tiny cell structures containing melanin pigments that give birds and other animals their color.
The findings suggest that the ancient bird was probably black and may have had a glossy or iridescent sheen, like swifts living today.
Based on its beak shape it probably ate insects, the researchers say.
The results will appear in the May 1 issue of the journal Proceedings of the Royal Society B.
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