New Study Sheds Light on Why Insects' Structural Color Changes during Fossilization

A new study discovers why and how structural colors of insects change during the fossilization process.

Modern insects have bright colors due to microscopic light-reflecting structures in their tissues. But the structural colors of fossilized insects are patchy and the original color changes during the fossilization process.

Researchers from the University of Bristol, U.K., have now found out what causes the original color of the insects to get destroyed during the burial process. The research team used modern beetles to explain color patterns in fossil records.

They carried out their experiment by simulating high pressures and temperatures that are found deep under the Earth's surface. They found that the beetles changed their color due to changes in the chemistry and physical architecture of the color-producing structures in their tissues.

"Our results explain a big mystery in the field of fossil color. By looking at what happens to structural colors in modern insects during fossilization experiments, we can now say exactly why and how structural colors change during the burial process," Dr. Maria McNamara, from University of Bristol, said in a statement.

"Now we know what key events in the geological history of sediments can cause color change. This will help us to pin down which fossils show colors that we can trust, and which have been altered."

McNamara and her colleagues also found that certain types of structural colors produced by 3-D photonic crystals are not found in the fossil record. These photonic crystals are the most complex color-producing structures known in nature.

Researchers have ruled out the possibility that these structures were not able to survive the fossilization process, as they are really tough and could survive the same burial conditions as other structural colors. This suggests that these structures evolved recently - within the last few million years, they said.

The research team also hopes the study could help in reconstructing the evolution of colors in insects. 

The findings of the study, "The fossil record of insect color illuminated by maturation experiments", are published online in the journal Geology. The research findings will be showcased at the Royal Society Summer Science Exhibition in London, from 1 to 7 July.