The Oldest Known Butterflies Existed Before Flowers
A new study raises intriguing questions about the evolutionary trajectory of butterflies and moths
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To help them slurp up tasty nectar from floral tubes, butterflies and moths have a long, tongue-like mouthpiece known as a proboscis. The prevailing (and very logical) theory about this handy appendage is that butterflies and moths evolved their proboscises in response to plants that developed flowers. But that theory might be wrong. As Ben Guarino of the Washington Post reports, a new study has uncovered evidence suggesting that butterflies and moths had proboscises millions of years before flowers came into existence.
While studying fossil cores dating to the late Triassic and early Jurassic periods, an international team of researchers discovered the fossilized remains of the tiny scales that coat the bodies of butterflies and moths. Using a needle tipped with a human nostril hair, Timo van Eldijk, a graduate student at Utrecht University in the Netherlands, was able to push 70 scales beneath a microscope.
“The nose hair has just the right length and springiness for getting a pollen grain, or in this case the butterfly scale, to adhere to it,” van Eldijk told Nicholas St. Fleur of the New York Times. “I was just provided these by my professor, I don’t know whose nose hair it was. It’s probably best not to ask.”
Van Eldijk then set about analyzing the structure of the scales. Some were solid and compact, which was not particularly unusual; previous research has shown that this structure was typical of early moths and butterflies, which used mandibles to chomp their food. But van Eldijk was surprised to discover that other scales were hollow—a feature only seen among moths and butterflies with proboscises.
"If you find the hollow scales,” van Eldijk told Rebecca Hersher of NPR, “you know the innovation of the proboscis must have occurred before that."
This discovery, described recently in the journal Science Advances, threw researchers for a loop because the scales are about 200 million years old, making them the oldest known Lepidoptera remains by about 10 millions years. Previous molecular studies on the creatures suggest a similar early evolution of proboscis-bearing butterflies and moths, Fabien Condamine, a butterfly researcher who was not involved in the study, tells Hersher.
The fossils are also about 70 million years older than the first flowers, raising intriguing questions about the evolution and function of the proboscis. It is possible that there is simply a gap in the fossil record, and flowers existed earlier than scientists realized. But the study authors believe the more likely explanation is that butterflies and moths evolved their proboscises before flowers came into being—possibly to help them lap up the sugary pollination drops produced by gymnosperms, the most common group of plants that sprung from the ground during the Jurassic.