Scientists Recreated the Long-Lost Chirps of Jurassic Insects. Listen to the Simulated Soundscape of 165 Million Years Ago

Amid the footsteps of dinosaurs and the rustle of ferns in the wind, the soundscape of Jurassic forests would have been filled with the musical chirps of cricket-like insects—and some of those calls would have been too high-pitched for humans to hear. Based on 165-million-year-old insect fossils, a team of scientists reproduced the sounds that these extinct creatures would have made, using close analysis of wing structures and artificial intelligence modeling. Their results, published on August 25 in the Proceedings of the National Academy of Sciences, also challenge a widely held idea about insect predator evolution.

Actual sounds from the Jurassic had no way to be preserved, and the voice-making organs of dinosaurs and mammals do not fossilize easily. But insects can offer key fossil clues to what the world of the dinosaurs sounded like. Although humans might describe insects as “singing,” most of them—including crickets and grasshoppers—produce noise in a way that’s more akin to playing a musical instrument.

This process, or “stridulation,” involves rubbing together body parts with ridged surfaces. Grasshoppers and katydids drag a leg across a wing, while crickets move one wing across the other. So, while vocal cords don’t really fossilize, legs and wings can.

Scientists discovered 20 fossilized Jurassic insects with their wings intact in Inner Mongolia, China. The remains belong to nine species related to crickets and katydids. To approximate the sounds that these structures would have made, the team examined their ridged features.

The number of teeth, as well as the spacing between them and the size of the vibrating area on the wing, would have determined the pitch and rhythm of the insects’ calls. The researchers analyzed these wings alongside the mechanics of modern insects’ stridulations, which they studied with lasers. They took into account the evolutionary relationships between these species and made computer simulations of how the prehistoric wings would have vibrated.

An A.I. model predicted what each call’s pattern would have been like, based on the fossilized wing shape. Most of the insects, the team suggests, produced low-frequency calls that aligned with what today’s crickets might emit—sounds that are around five kilohertz. Many of these were “pure tone” calls, or musical notes of only one frequency.