Researchers Discover Dinosaur with Shimmering Rainbow Feathers Like a Hummingbird

The almost complete Caihong juji fossil unearthed by paleontologist in China is believed to be 161 million years old, and its asymmetrical feathers are similar to the feathers used by bird to steer while flying. Scientists believe the crest played a significant role in mating, along with the shiny feathers.

The skull of Caihong juji.

It could be that Caihong's "rainbow" feathers were used to attract mates, just like modern peacocks use their colourful tails. By looking at the feathers of C. juji with a scanning electron microscope, a team led by China's Shenyang Normal University was able to speculate about its once-dazzling coloration. These pigments were nothing but the remnants of an organelle called melanosomes. The new species - called Caihong juji, Mandarin for "rainbow with the big crest" - is described in a study published by an worldwide team of scientists, including Chad Eliason, a postdoctoral researcher at The Field Museum.

"I was shocked by its beautifully preserved feathers, even though I had seen many feathered dinosaur fossils previously", said Xing Xu, a paleontologist at the Chinese Academy of Sciences and a co-author of the study.

"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.

A new bird-like dinosaur was discovered in the North-East of China, in the Hebei Province.

When dinosaur experts studied the fossil they could see evidence of brightly-coloured plumage. "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", explains Eliason.

From here, the researchers are aiming to work out how Caihong developed such a unique look, something they describe as evidence of mosaic evolution, where distinct traits evolve independently from one another.

Preserved in the slab of rock where Caihong juji was found were impressions made by its feathers, along with impressions made by the microscopic melanosomes themselves.

In addition to being the oldest example of a species with rainbow feathers, the newly discovered dinosaur is the earliest known animal with asymmetrical feathers, a feature that allows modern birds to steer or turn while flying. While it possessed many bird-like characteristics, researchers doubted whether it could actually fly. The bony crest represents a more ancient dinosaur feature, the University of Texas at Austin noted, while the iridescence, which could have helped it signal to potential mates, is newer. The researchers, writing in Nature Communications, report that the iridescent feathers would have resembled those of modern hummingbirds.

Julia Clarke, a coauthor and paleontologist at the University of Texas, says that the melanosome database could help solve a number of future scientific puzzles-especially if it continues to grow. "It has a velociraptor-type skull on the body of this very avian, fully feathered, fluffy kind of form".

  • Kyle Peterson