According to a new study, Microraptors—four-winged, feathered dinosaurs that lived 125 million years ago—sported Earth's earliest known iridescence, as pictured in this illustration.
Recent research suggests the pigeon-size Microraptor's feathers glimmered black and blue in sunlight, like feathers of modern crows or grackles.
The findings are the earliest evidence of iridescence in any creature-bird or dinosaur, said study leader Julia Clarke, a paleontologist at the University of Texas at Austin.
Clarke and colleagues also suggest this iridescent coloring may have helped make Microraptor's tail feathers even more eye-catching to mates.
Using an electron microscope, the researchers compared tiny, pigment-containing structures called melanosomes in a Microraptor fossil to melanosomes of living birds.
The team found that Microraptor's melanosomes were narrow, elongated, and organized in a sheetlike orientation—features that produce an iridescent sheen on modern feathers.
"This study gives us an unprecedented glimpse at what this animal looked like when it was alive," study team member Mark Norell, chair of the American Museum of Natural History's Division of Paleontology, said in a statement.
(See "True-Color Dinosaur Revealed: First Full-Body Rendering.")
The new findings are detailed in this week's issue of the journal Science.