One of the most commonly asked questions about long-extinct ancient animals is what they looked like and, more specifically, what color they once were. Now, researchers have been able to figure out the color of moths that lived an astonishing 200 million years ago, and they sported a wonderful metallic sheen.
Figuring out the color that many creatures were can be a difficult question to answer, but for some critters we can have a fairly good go at it. This comes down to the main divide between those animals that have pigmented color, like the hairs on your head or the skin on a lizard, and structural color as seen in the feathers of some birds or the casings of many beetles. In general, pigments are more fragile and less likely to fossilize (although nowadays we’re finding out otherwise), while structures can persist.
And it is the structure of these ancient insects’ wings that have enabled researchers to figure out what color they once were, publishing their results in Science Advances.
They were able to describe the optical properties of the scales in ancient fossilized Lepidoptera by using a whole gamut of microscopy techniques to image the minuscule structures, including scanning electron microscopy, transmission electron microscopy, and, finally, something called confocal laser scanning microscopy.
By doing this they could reconstruct how the scales were likely arranged on these early insects and, therefore, describe the earliest evidence for structural colors in any insect fossil to date. Comparing how the scales were arranged on the wings of these ancient Lepidoptera to a modern-day group of primitive moths known as Micropterigidae, the researchers could begin to infer what colors were likely found on these long-extinct animals.
It turns out that over 200 million, years very little has changed. The preserved arrangement and well as the herringbone ornamentation of the scales on the wings of these Jurassic moths is almost identical to those of their living counterparts. This suggests that they would most likely have been colored in exactly the same way with browns, purples, yellows, and cream hues.
But what is more, the researchers are able to work out that these early insects would also have had a beautiful metallic sheen to their wings. They can tell this by the fact that the way in which the scales would have been arranged, it would have scattered light in a way that causes such a shimmer. Once again, this is consistent with how many different species of Micropterigidae look today.
“These findings have broader implications,” enthuses Professor Wang Bo, who led the research. Because similar wing scales are prevalent in the Jurassic fossil record, it means that they most likely evolved incredibly early in the moths and butterfly lineage, before massively diversifying in the Cretaceous.