A multinational group of scientists was able to use the Jurassic fossils of katydid ancestors to reproduce the sounds they made.
The study, published in the Proceedings of the National Academy of Sciences journal, looked at 20 fossils from nine species taken from a formation roughly 143 miles northeast of Beijing.
Unlike the sound-producing body parts of creatures such as dinosaurs, which rarely fossilize well, some sound-producing parts of prehistoric insects did fossilize well, the study’s authors said in their abstract. Those include parts on their forelegs rubbed together to produce sound, as crickets do.
“Our findings reveal a wide variety of call frequencies. Several species produced pure, low-pitched sounds like modern crickets, whilst others produced higher frequencies, similar to our native leafhoppers,” Thorin Jonsson, a researcher at the University of Graz in Austria and one of the study’s authors, said in a statement from the school.
Mr. Jonsson also noted that one of the species produced sounds in the ultrasonic range beyond the capabilities of human hearing. The same range of frequencies is used by bats, which evolved 100 million years after the insects used in the study.
The study’s authors said that, as opposed to theories that insects capable of ultrasounds developed them to deal with bats, the species studied developed ultrasounds to deal with other predators roughly 165 million years ago.
Ensuring their sounds were audible amid noise from other prehistoric insects is another possible factor.
“One hundred sixty-five million years ago, the insect community may have already had sophisticated acoustic niches — multiple species occupying different frequency bands from low to high,” Jun-Jie Gu, another one of the study’s authors, told The New York Times.
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