Newly Discovered Dino Had a Rainbow of Shiny Feathers

The fossilized creature was likely a blend of hummingbird and crow

Artist's concept of Caihong, a crow-sized iridescent dinosaur from the Jurassic Period. Velizar Simeonovski/The Field Museum

These days, a new feathered dinosaur may seem like just another addition to the growing catalog of these ancient beasts. But the latest fossil wasn’t just feathered, it was delightfully colorful. Sublimely preserved, the critter ​was dubbed ​Caihong juji, which is Mandarin for "rainbow with a big crest," in tribute to the microscopic structures in the fossil that suggest this Jurassic dino sported a coat of iridescent feathers, Michael Greshko reports for National Geographic.

The new species of dinosaur was identified from a fossil discovered by a farmer in the Hebei Province in northeastern China. Roughly the size of a crow, the creature lived roughly 161 million years ago. Though pretty, its colors likely had a purpose. Researchers believe that the rainbow plumage could have been used for social or sexual behavior. As Greshko reports, it was likely akin to a modern peacock’s tail.

“I was shocked by its beautifully preserved feathers, even though I had seen many feathered dinosaur fossils previously,” Xing Xu, paleontologist​ and co-author on the a new study in the journal Nature that describes the fossil, tells Greshko.

The researchers examined the fossil using scanning electron microscope (SEM), which can tease through the tiny details of a surface. As Laura Geggel writes for Live Science, the instrument revealed melanosomes, or microscopic structures that are responsible for pigmentation in modern bird feathers. The shape of these structures determines the color of the creatures' feathers.

Studying these structures, researchers learned that Caihong’s feathers were mostly dark. But its head and neck had pancake-shaped melanosomes ordered into sheets, which are similar to those of modern hummingbirds’ iridescent plumage, Will Dunham writes for Reuters. This suggests Caihong had a flashy, rainbow head. The researchers were unable to exactly match Caihong’s colors but are confident it had an iridescent glimmer, Greshko writes.

"Hummingbirds have bright, iridescent feathers, but if you took a hummingbird feather and smashed it into tiny pieces, you'd only see black dust," Chad Eliason, an author of the new study, says in a statement. "The pigment in the feathers is black, but the shapes of the melanosomes that produce that pigment are what make the colors in hummingbird feathers that we see."

Caihong’s feathers were likely both fluffy and sleek, with a mix of fuzzy down and streamlined quill-shaped pennaceous feathers. Its tail feathers were asymmetrical, Dunham reports, a key aerodynamic trait that allows modern birds to steer while flying. As Greshko writes, Caihong is the oldest known example of asymmetrical feathers, suggesting that the trait developed in tails prior to it developing in wings.

While Caihong is a feathered dinosaur that shares many characteristics with modern birds, Dunham reports that researchers are uncertain if it was capable of getting airborne. Instead, the two-legged predator was more akin to velociraptors with sharp teeth and bony eyebrow crests. This makes it an odd combination of a fluffy dinosaur with a raptor’s shape, Greshko writes.

“To be honest, I am not sure what function the feathers have, and I don’t think that you can completely exclude the possibility that the feathers helped the animal to get in the air,” paleontologist Xing Xu of the Chinese Academy of Sciences tells Dunham.

Caihong isn’t the first iridescent dinosaur to be discovered. Researchers think that Microraptor, a similarly-sized dinosaur that lived 120 million years ago, was completely covered in dark feathers with an iridescent blue gleam, similar to modern crows.

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