Listen in on the Sounds of a Jurassic Period Forest

In a world without humans or bats, the sounds of a Jurassic forest in Mongolia can be heard through the echoes of katydids. These insects, belonging to the order Orthoptera, are known for their ability to create sounds by rubbing a file on the underside of their left forewing against a plectrum on the edge of their right forewing. This scraping motion is further amplified by a drum-like cell, while the amplitude of the sound can be adjusted by the pressure applied by the file on the plectrum.

Katydids in the Jurassic period had highly specialized ears located on their front legs, just below the knees. These ears were similar in structure to those of mammals, allowing them to pick up each other's calls. Despite the absence of bats, which would have evolved millions of years later, katydids had no competition for airspace from them.

In fact, the forests were teeming with insectivorous mammals and reptiles, such as tree-climbing theropods and flying pterosaurs, which might have been deterred by the sound of the katydids' unique melodies.

Interestingly, the study suggests that the ability to produce sound through wing stridulation may have evolved before the development of hearing as a defensive tool to ward off terrestrial predators. Although there were no bats or humans around to appreciate the sounds, the katydids certainly made sure their voices were heard in their Jurassic forest.