Scientists have uncovered an intriguing connection between ancient fireflies and the time when dinosaurs roamed the Earth. Recent research confirms that a variety of firefly species illuminated the nights during the late Mesozoic era. This revelation stems from the discovery of a fossilized firefly species that was trapped in 99 million-year-old amber found in northern Myanmar. This beetle, named Flammarionella hehaikuni, is only the second firefly species identified from the Mesozoic period.
In a July 2022 study, researchers estimated that fireflies developed the ability to glow while flying at least 100 million years ago, following the examination of the first Mesozoic firefly fossil identified in 2015. However, the softer bodies of fireflies make it challenging for them to be preserved as fossils, complicating the study of their evolution and bioluminescence.
The recent identification of Flammarionella hehaikuni has provided a new perspective on the early evolution of fireflies. Chenyang Cai, a professor at the Nanjing Institute of Geology and Palaeontology, highlighted the significance of this fossil in bridging gaps in understanding the evolutionary history of lampyroid beetles, which include fireflies. He stated, "The fossil helps bridge gaps in understanding the evolutionary history of the lampyroid beetles... and shows that key traits, like abdominal light organs, have remained consistent since the mid-Cretaceous." Cai's enthusiasm was evident as he added, “How cool is it that dinosaurs once saw fireflies flying at dusk?”
When Cai first examined the firefly fossil in 2016, he initially believed it was a type of click beetle due to its unique serrate antennae. However, upon a closer look in late 2022, he recognized the well-preserved light organ characteristic of fireflies. This fossil discovery is particularly noteworthy because there are only ten known past firefly species identified from fossils. Dr. Oliver Keller, a specialist in firefly systematics at the University of Michigan, noted the rarity of firefly fossils from this era, emphasizing that the discovery of this new species could help refine the dating of firefly evolution.
Fireflies are known to glow for various reasons, including defence, communication, and attracting mates. While it’s difficult to imagine what the light displays looked like 100 million years ago, Keller suggested they may have been similar to the glowing patterns we see today. The study authors named the new beetle in honour of French astronomer Camille Flammarion and Haikun He, an amateur collector who contributed other amber specimens to the research.
Today, over 2,000 firefly species exist, and the authors hypothesize that the ancient species belongs to the Luciolinae subfamily, which includes about 450 species today. However, no current Luciolinae species has the peculiar antennae of the fossil, indicating differences that may also be related to the insect's sex. The newly identified fossil is that of a female firefly.
The less-than-1-centimetre-long fossil indicates that Mesozoic fireflies had a more diverse range of light organs than previously believed, although they still share similarities with modern fireflies. The authors hope that additional firefly fossils from the Mesozoic era will be found, further illuminating the origins of these fascinating bioluminescent beetles. Dr. Kundrata, one of the co-authors, expressed optimism for future discoveries that could shed light on the diversity and morphology of early fireflies.