The oldest known fossil of a singing cicada reveals that these insects were making music during the Eocene epoch — long before humans existed.
The fossil represents a new cicada species, Eoplatypleura messelensis, which lived about 47.2 million years ago. The discovery pushes back the timeline for when cicadas started to sing by about 17 million years and offers clues into the evolution of insect communication, scientists report April 29 in Scientific Reports.
“The fossil has been in the collection of the Senckenberg Museum since 1986,” says biological paleontologist Sonja Wedmann. It had been referred to as a cicada fossil back in 1988, but it was only when Hui Jiang, a specialist in singing cicadas, joined the museum in Frankfurt, Germany that the team brought together the whole collection of cicadas to study them.
Jiang was surprised to find not one but two singing cicada fossils from the Eocene. The two adult female specimens were both preserved in oil shale, a fine-grained rock that locks in delicate details. The fossils were from the Messel Pit, a famous fossil site near Darmstadt, Germany. A close look at their wings showed the insects measured about 26.5 millimeters long with a wingspan of 68.2 millimeters, and their wing vein patterns revealed they belonged to the Platypleurini tribe — a group of modern singing cicadas that had no fossil record until now.
“Cicadas are capable of producing some of the loudest sounds among all insects,” says Jiang, now at the University of Bonn in Germany. Though typically only male cicadas sing, finding the two fossilized Platypleurini females from the Eocene offers clues about the history of the insects’ song. Earlier fossils from other cicada groups had previously suggested the insects started singing around 30 million years ago.
Finding the fossils in Germany is also striking because scientists had assumed that cicadas only spread into Eurasia after Africa and Eurasia’s tectonic collision some 30 to 25 million years ago. However, the fossil hints that cicadas were there much earlier. Estimates of past climates suggest that the Messel area once averaged around 22 °C (71.6 °F), making it a suitable home for cicadas 47 million years ago. Platypleurini cicadas alive today live in similar temperatures in tropical and subtropical parts of Africa and Asia.
“The cicada family is poorly represented in the fossil record, says Daniel Pauvik, an insect ecologist at Bowling Green State University in Ohio. Finding these fossils from so long ago is important. The Eocene epoch, he says, “marks sort of the dawn or beginning of a lot of different groups that we have around today.” That emergence includes not only insects, but also some birds and even reptiles.
This Platypleurini cicada fossil, Pauvik says, hints at “the early origins of the whole group in that particular part of the world,” and “maybe for the whole planet.”