Speckles on 390-million-year-old trilobite fossils (pictured) may have helped to camouflage the marine invertebrates.

Credit: CHRISTOPHER MCROBERTS

A team led by Christopher McRoberts, of the State University of New York at Cortland and Thomas Hegna at Western Illinois University in Macomb examined more than 25 Eldredgeops rana trilobites that were discovered in central and western New York state. The fossil exoskeletons were dotted with regular arrangements of a variable number of spots — more than 500 in some cases. Chemical and mineral analyses indicated that spots are of similar composition to the rest of the fossil, suggesting the markings are not artefacts.

No pigment molecules were preserved, but the authors speculate that the spots may have scattered sunlight and blurred a trilobite's shadow.

Geology http://dx.doi.org/10.1130/G34158.1 (2013)