Despite being tens of millions of years old, some beetle fossils appear almost as they did in life. Not only are their shape and structure preserved, but so are the actual colors of their shells, which have changed only slightly in the intervening eons.
Though relatively little-known, these fossils represent the purest of biological colors retrieved from deep time, far richer than much-celebrated pigment traces of dinosaur plumage and more varied than the hues of a few ancient plants.
In a study published Sept. 27 in Proceedings of the Royal Society B, researchers led by Yale University paleogeologist Maria McNamara analyzed 10 of these spectacular beetle fossils, ranging from 15 million to 47 million years old, which owe their enduring shades to the phenomenon of structural coloration. Unlike pigments, which generate color from light bouncing off a chemical, structural colors are produced by the interaction of light with nanometer-scale surface geometries.