Imagine a beetle buzzing through a Cretaceous forest 100 million years ago, its body glowing softly in the dark. Now scientists have found one of those ancient beetles perfectly preserved in amber, and it's revealing secrets about how fireflies learned to light up.
Researchers discovered the remarkable fossil in Kachin amber, a golden gemstone dug from mines in Myanmar. What makes this specimen so special is its incredible state of preservation. The beetle still has its elaborate antennae — 12 segments long, with unusual branched structures — and its abdominal light-emitting organs completely intact. Finding both features preserved together in a single 100-million-year-old fossil is extraordinarily rare.
The new species has been named Icaroramus perisi. It belonged to an extinct family of beetles called Cretophengodidae, which lived during the time of the dinosaurs. The study was led by Li Yanda, a doctoral student at the University of Bristol, along with Professor Cai Chenyang from the Nanjing Institute of Geology and Paleontology in China. Their findings appeared in the journal Proceedings of the Royal Society B in late July.
The beetle's antennae are its most striking feature. Each segment bears two pairs of side branches, each pair shaped differently. One pair near the base has widened tips covered in coarse hairs, while the other pair closer to the middle is slimmer and covered only in fine hairs. According to the researchers, this branching pattern is unlike anything seen in beetles today. They believe the antennae helped the beetle detect chemical scent signals called pheromones, which it likely used to find mates.
As for the glow, scientists think it served a different purpose than in modern fireflies. Living fireflies that use light to attract mates tend to have simple, unbranched antennae. But Icaroramus had both bright organs and elaborate antennae — a combination that doesn't match modern fireflies. The researchers believe the light probably worked as a warning signal to scare away predators, essentially saying "don't eat me, I'm toxic." A role in mating couldn't be ruled out completely, but defense seems most likely.
Together, these features tell us something important: by the mid-Cretaceous, around 100 million years ago, beetles had already evolved sophisticated ways to sense their world and communicate with each other. Multiple strategies — chemical signals, bright colors, and bioluminescence — had already emerged in the ancient ancestors of today's fireflies.
For the researchers, this fossil is like a time capsule. Soft tissues like antennae and light organs almost never survive fossilization, making this specimen an exceptionally rare window into how these remarkable communication systems first evolved.