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5 December 2013 11:26 am ,
Vol. 342 ,
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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31 July 2003 (All day)
When animals turn into fossils, they become faded, dingy semblances of their former selves. Even if original tissue remains, pigments can be altered over the eons. Now a pair of researchers has shown a way to deduce the true color of iridescent arthropods by measuring reflective layers on their exoskeletons.
Many animals are tinted with pigments, but these compounds aren't the only source of color. Minuscule ridges called diffraction gratings reflect and split light into various wavelengths. Iridescent color can also arise from surfaces called multilayer reflectors, which are found on some butterfly wings, bird feathers, and beetle carapaces.
Sparkling colors have also been seen on 50-million-year-old beetles from Messel, Germany, a treasure-trove of exquisitely well-preserved fossils. Such color is rare, and indeed it fades away as soon as these water-rich fossils dry out. Andrew Parker, a zoologist at the University of Oxford, U.K., teamed up with David McKenzie, a physicist at the University of Sydney, Australia, to study a specimen with blue coverings on its wings. Looking with an electron microscope, they found flat, smooth layers. As in living beetles, the layers alternated between 80 and 95 nanometers thick and bend light in different ways.
A computer model predicted that as light rays hit the layers, they would interfere with each other and reflect light primarily at a wavelength of 490 nanometers. That was smack dab in the middle of the spectrum of light reflected by the specimen, Parker and McKenzie report this week in Biology Letters. They suggest that measuring fossil multilayers could also be used to identify true colors in drab specimens collected elsewhere. "This beetle might be a Rosetta stone for fossil colors," Parker says, adding that similar features have been seen in trilobites, crustaceans, and other fossil arthropods.
The approach is "a very elegant way of showing that--with exceptionally preserved material--you may be able to infer what the color was," says paleontologist Derek Briggs of Yale University. The method might be able to paint in details of fossil life, revealing for example whether extinct animals once had warning coloration. Or, a host of iridescent animals might indicate that an ancient environment was particularly sunny, says Parker. Briggs's hunch, however, is that chemical changes eventually wipe out the minuscule layers.