Crickets and katydids carry their instrument on the wing: a serrated file and a scraper that fossilize well. From 20 fossil wings of nine species in Inner Mongolia, researchers reconstructed how they would have sounded about 165 million years ago. Most calls were pure tones around 5 to 7 kilohertz; one species sang above 20 kilohertz, in ultrasound. Nautilus’s write-up embeds a recording of the result.