Twenty Jurassic insect fossils from Inner Mongolia let researchers reconstruct 165-million-year-old chirps, with most species producing cricket-like calls near 5 kilohertz and one likely reaching 20 to 22 kilohertz.
Wing ridges, tooth spacing and vibrating areas preserved in nine cricket- and katydid-related species were analyzed against modern insects’ mechanics, then modeled with computer simulations and AI to predict pitch and rhythm.
Sigmaboilus peregrinus appears to have emitted ultrasonic calls just above human hearing, pushing such signals back to millions of years before the first bats and challenging the idea that bat predation drove their origin.
The study instead points to pressure from other predators or to competition within dense insect choruses, suggesting Jurassic forests had a richer and more varied soundscape than previously assumed.
Published in PNAS on Aug. 25, the work offers a template for reconstructing other prehistoric insect sounds and broadening evidence about ancient ecosystems beyond bones and footprints.