Long dead moths alive with color

Yale researchers are coloring in moths that have been dead for 50 million years.

A team of researchers including Derek Briggs, director of the Peabody Museum, discovered for the first time the patterns of color on an ancient moth derived from a 50 million-year-old fossil from Germany. This study, published in PLOS Biology in November, was a collaboration with geologists in Ireland and Germany and the third in a series of papers on the color of ancient organisms that Briggs’ team has worked on. Maria McNamara, a postdoctorate in the Department of Geology and Geophysics and a co-author of the paper, said the research is significant because it uses new techniques to analyze ancient fossils and has implications for understanding prehistoric ecosystems.

“The work is significant, not least because it represents the first time that original coloration has been reconstructed for a fossil lepidopteran, and the first time that the function of structural color has been deducted for a fossil organism,” McNamara said.

The lack of information about the colors of animals has always been an impediment in the bid of scientists to understand their behavior and how they interacted with other animals, Briggs said.

The work on the specimen started in August 2010 and the team worked through several methods before reaching the result, McNamara said. The original color was not preserved in the fossils, so the team used electron microscopy techniques and analysis of the structures to interpret the colors, Briggs said. They examined the fossilized bodies of daytime moths, which were originally found at the Messel oil shale pit near Frankfurt, Germany.

The team only analyzed the colors of a single 50 million-year-old moth, reconstructing its colors based on preserved ultrasound detail. They found the structural color of the moth’s forewings to be a matte, noniridescent yellow-green. Elsewhere the moth was brown, blue and green-cyan.

Through the research, the team was able to show that the fossil moths had used their colors to help them survive. When it was eating and vulnerable to attack, the bright colors warned off predators; when the moth was at rest in leafy habitats, the duller colors provided camouflage. McNamara said the “inferred functions of the colors” were similar to those of the living relatives of these moths.

“It is important to know the original colors of extinct animals because this can say a lot about ancient behaviors and ecological interactions, which may be lacking from the whole animal fossils alone,” said Andrew Parker, an honorary research fellow at Oxford University.

Parker said that the finding was important because it took into account the potential changes to the insect’s shell during the process of fossilization. He expressed hope that the method could be applied to other fossils that have been preserved in different ways, making it universally applicable. The role of color as an evolutionary adaptation can probably be traced back to the first highly mobile predator with vision, Parker said, which could have appeared as early as 520 million years ago.

The study’s co-authors include Heeso Noh and Hui Cao of Yale’s Department of Applied Physics.

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