Why Colorful Dinosaur Feathers Evolved: Not to Fly But to Display

Birds aren't the only ones with feathers. Dinosaurs also possessed colorful plumage. But why did these ancient creatures have feathers long before early bird species, such as Archaeopteryx, attempted to fly? Scientists may now have the answer.

Dinosaurs and birds are close relatives. In fact, birds descend from a branch of medium-sized predatory dinosaurs known as theropods. Dinosaurs such as the T. rex and velociraptors are part of this two-legged group of dinosaurs. Yet what's interesting to note is that, like the birds that followed them, these dinosaurs had feathers.

"Up until now, the evolution of feathers was mainly considered to be an adaptation related to flight or to warm-bloodedness, seasoned with few speculations about display capabilities," said Marie-Clair Koschowitz, the first author of the new study, in a news release. "I was never really convinced by any of these theories. There had to be some particularly important feature attached to feathers that makes them so unique and caused them to spread so rapidly amongst the ancestors we know today."

In this case, the researchers examined dinosaur fossil finds. This showed them that the precursors to feathers resembled hairs similar to mammals' fur and served primarily to protect smaller predatory dinosaurs. Eventually, these small hair-like forerunners became large and flat, allowing for the display of color.

"Feathers enable a much more noticeable optical signaling than fur would allow," said Koschowitz. "Iridescent birds of paradise and hummingbirds are just two among a wealth of examples."

This suggests that feathers may have evolved for display rather than anything else. With their variety of colors and patterns, they could have acted as signaling for dinosaurs rather than having evolved for flight. Not only that, but dinosaurs would have been able to maintain these bright patterns while at the same time being warm blooded.

The findings are published in the journal Science.