Crystal Caskets For Pigments

Many fossils are tinted with color, but few have had their pigments chemically analyzed. Now, researchers report the oldest pigment molecules extracted from fossils of a known organism—namely, the roughly 340 million-year-old fossils of marine animals called crinoids, which are related to starfish and urchins (Geology, DOI: 10.1130/g33792.1). The techniques used to measure the pigments could be easily applied to other tinted fossils, says Christina E. O’Malley, who did the analysis with paleontologist William I. Ausich and chemist Yu-Ping Chin, all of Ohio State University. In addition to reconstructing the color palette of ancient organisms, O’Malley hopes that organic molecules preserved in ancient fossils could help unravel phylogenetic relationships among fossilized and contemporary organisms. Crinoid fossils can vary in color from white to brown and reddish purple, O’Malley says. The team collected about a gram of sample from fossils of three crinoid species and found that the complex mixture of pigments consists of quinones derived from aromatic or polycyclic aromatic compounds.