These studies also have further implications. For one, the finding that melanosomes are so common inside animals’ bodies may overhaul our very understanding of melanin’s function, says McNamara. “There’s the potential that melanin didn’t evolve for color at all,” she said. “That role may actually be secondary to much more important physiological functions.” Her research indicates that it may have an important role in homeostasis, or regulation of the internal chemical and physical state of the body, and the balance of its metallic elements. “A big question now is does this apply to the first, most primitive vertebrates?” said McNamara. “Can we find fossil evidence of this? Which function of melanin is evolutionarily primitive—production of color or homeostasis?”
At the same time, the findings imply that we may need to review our understanding of the colors of ancient animals. That’s because fossil melanosomes previously assumed to represent external hues may in fact be from internal tissues, especially if the fossil has been disturbed over time. McNamara says her research has also shown that melanosomes can change shape and shrink over the course of millions of years, potentially affecting color reconstructions. [...]
Shawkey is looking into such questions, with one of his recent studies indicating that the wing color of birds may play an important role in flight efficiency by leading to different rates of heating. “What started as a novelty of deciphering dinosaur colors has turned into a very serious field which is studying the origins of key pigment systems, how the evolution of colorful structures may have helped drive major evolutionary transitions like the origin of flight, and how color is related to ecology and sexual selection,” said Steve Brusatte, a vertebrate paleontologist and evolutionary biologist at the University of Edinburgh. “When I was growing up, so many of the dinosaur books I read in school said that we would never know what color they were. But as is so often the case in science, it was silly to treat this as impossible.”
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