Hummingbirds are so tiny and quick you might not even notice one whirring through the air. But the sight of a miniscule bird, wings moving so fast they’re just an iridescent blur, is a beautiful vision indeed.

A new fossil discovery is telling scientists more about where these tiny creatures came from, and how they evolved. The study was led by Daniel Ksepka from North Carolina State University and was recently detailed in the journal Proceedings of the Royal Society B.

In southwestern Wyoming, in a dried out lakebed known as the Green River Formation, a small, fossilized bird was unearthed. Measuring only 4.5 inches long, this 50-million-year-old fossil was related to the common ancestor of hummingbirds and another type of tiny bird known as a swift.

Swifts and hummingbirds are members of the order Apodiformes—Latin for “footless.” Apodiformes are well known for their unusual and amazing ability to speed through the air. They spend most of their lives airborne, using their diminuitive legs almost exclusively for perching. Swifts feed on insects while flying through the air, whereas hummingbirds have adapted the ability to hover while feeding.

Eocypselus rowei, as the new fossil was dubbed, branched off from the common ancestor of swifts and hummingbirds. Unfortunately, it represents the end of its line—it left no descendant species after it became extinct.

But modern hummingbirds and swifts are offering insight into E. rowei’s ancient living habits. Its wings were somewhere in between the lengths of swift wings, which are long, and those of hummingbirds, which are shorter. The ancient bird probably practiced similar aerial acrobatics to today’s Apodiformes, and also most likely fed on insects.

The feathers of E. rowei were intricately preserved, allowing Ksepka and colleagues to using scanning electron microscopy to find melanosomes—molecules that indicate the color of ancient life—in the fossil wings. Its wings, the researchers determined, were most likely black and shiny.

E. rowei was as mini a bird as a hummingbird—it weighed less than one ounce. As Apodiformes shared an evolutionary history with E. rowei, scientists think that hummingbirds and swifts probably started out the tiny birds they are today, and then evolved their quick-moving flight skills later on in their evolutionary story.

Read more about Eocypselus rowei in the journal Proceedings of the Royal Society B.

The Paleontological Research Institution, Ithaca, New York, is pleased to sponsor Paleontology content for This View of Life. Founded in 1932, PRI has outstanding programs in research, collections, and publications, and is a national leader in development of informal Earth science education resources for educators and the general public.


Published On: May 10, 2013

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