"Our results show that the colors of the fossil beetles we studied changed during the fossilization process," lead author Maria McNamara told Discovery News.
"In particular, the colors have been shifted towards the red end of the spectrum -- not completely, but enough to make, for example, a formerly blue beetle more green, and a formerly yellow beetle more orange," added McNamara, a postdoctoral research fellow in the Department of Geology and Geophysics at Yale University.
She and her colleagues made the determination after studying fossil beetle specimens dating from 15 to 47 million years ago. The beetles once lived in what are now Idaho (U.S.), Germany, and other locations.
The beetles' flashy yellow, green, blue, red, and other metallic car-like hues were due to structural color, meaning color that results from interference of light. The ocean is blue, for example, because water absorbs colors in the red part of the light spectrum, leaving behind blue.
The fossil beetles achieved their light manipulation, not with water, but with "very fine layers, millionths of a meter, in the outermost levels of the beetle cuticle," McNamara explained.