Remarkably preserved beetles dug up from fossil pits in Europe and the United States have given scientists the most accurate picture to date of the colors that adorned their exoskeletons 15 to 47-million years ago. Unlike coloration that relies on pigments, which degrades over time, (read a recent story from The Scientist about dinosaur plumage) the striking metallic colors of beetles and other insects are generated by the scattering of light from complex nanostructures in their caparaces.
Researchers led by Yale University paleontologist Maria McNamara analyzed micro-scale fossil samples with electron microscopy and then used computer models to predict the color that would have been displayed by the surfaces millions of years ago. They found that the surfaces have changed slightly, making the colors appear redder than they had when the insects were alive. “You need to mentally redshift the color. If it’s green, it’s actually a little more on the yellow side. If it’s blue, it’s a little greener,” McNamara told Wired.