The familiar buzz of a cicada is a hallmark of summer, but these insects have a history that extends deep into the ancient past. Long before they became a regular part of the seasonal soundscape, their ancestors existed in prehistoric ecosystems. A cicada fossil represents the preserved remains or imprints of these ancient insects, captured in stone or other materials over millions of years. These fossils are windows into the deep history of a well-known insect group, connecting the cicadas in modern backyards to a lineage that has survived major geological and environmental shifts.
The Earliest Cicada Ancestors
The evolutionary story of cicadas begins in the Mesozoic Era, with the earliest definitive fossils dating back to the Triassic period. These ancient relatives were not identical to the insects we see today, but they possessed the foundational traits that define the group. Mesozoic cicada fossils include a range of ancestral types, some of which are considered stem cicadoids—insects that are related to but predate the common ancestor of all modern cicadas.
By the Middle Jurassic, the two main families of cicadas, the Tettigarctidae (hairy cicadas) and the Cicadidae (true or singing cicadas), may have already diverged. Fossils from this time, such as those of Davispia, reveal insects with the characteristic wing shape and vein patterns that are unmistakably cicada-like. Although these early ancestors may have differed in size and other subtle anatomical details from their modern counterparts, the fundamental body plan was established hundreds of millions of years ago.
Preservation and Notable Fossil Sites
The most common method of preservation is through compression fossils, where the insect’s body is flattened between layers of fine-grained sediment. This process can preserve intricate details, such as the complex vein patterns on their wings and even body coloration. Another form of preservation occurs when a cicada becomes trapped in tree resin, which hardens over millennia into amber, creating a three-dimensional tomb that perfectly captures the insect.
These fossils are not found everywhere but are concentrated in specific geological deposits known as lagerstätten, which are areas of exceptional preservation. The Yixian Formation in China has yielded many important Mesozoic-era cicada fossils, providing a glimpse into their early diversification. In North America, the Green River Formation, spanning parts of Colorado, Utah, and Wyoming, is another significant site. A more recent, yet highly informative, location is the Messel Pit in Germany, a former volcanic lake where 47-million-year-old cicada fossils have been unearthed from oil shale.
Scientific Insights from Fossils
Studying cicada fossils provides more than just a record of their existence; it offers profound insights into insect evolution and ancient environments. The fossils allow scientists to trace the development of specific anatomical features. For example, the discovery of a 47-million-year-old singing cicada fossil, Eoplatypleura messelensis, pushes back the timeline for when these insects first produced their famous sounds.
Fossil evidence also helps map the global spread and diversification of cicadas over millions of years. The presence of certain cicada groups in locations like Germany challenges previous theories about their migration patterns, suggesting they inhabited Eurasia much earlier than once believed. Furthermore, because modern cicadas are often adapted to specific climates, their ancient relatives serve as valuable paleo-indicators.