Metals left behind in dinosaur fossils might offer a clue to what colors graced their feathers. Scientists have used x-rays to map the copper, zinc and calcium in feathers from living birds. These metals revealed where the birds were marked with different forms of melanin pigment, the team reported September 23 in the journal Scientific Reports.

"This work on modern animals now provides another chemical 'key' for helping us to accurately reconstruct the appearance of long extinct animals," coauthor Roy Wogelius, of the University of Manchester in England, said in a statement.

Melanin is the dominant pigment in birds and other mammals, and colors our skin, eyes and hair. One type of melanin, called eumelanin, creates a black or dark brown hue. Another, called pheomelanin, is responsible for a reddish or yellow color. Despite its importance, not much is known about how melanin interacts with different elements.