Updated

Updated · Sci.News · Aug 25

Researchers Reconstruct 165-Million-Year-Old Ultrasonic Insect Calls, Predating Bats by 55 Million Years

Updated

Updated · Sci.News · Aug 25

Researchers Reconstruct 165-Million-Year-Old Ultrasonic Insect Calls, Predating Bats by 55 Million Years

Q: If bats didn't force insects to evolve ultrasonic calls 165 million years ago, what terrifying ancient predator actually did?

It was most likely not one single “terrifying” predator, but early small insect-eating mammals — and possibly other ground predators such as reptilian or non-mammalian synapsid lineages — that pressured Jurassic insects to shift into higher-frequency sound. The new PNAS study says bats cannot explain ultrasonic insect calls 165 million years ago because bats evolved roughly 55 million years later. Instead, the researchers point to early mammals and other predators that were already capable of listening in on insect songs. That fits with broader evolutionary evidence: early mammals were small, often nocturnal insectivores, and mammalian hearing was becoming better at detecting higher-frequency airborne sounds as the middle ear evolved. The researchers also argue predator pressure was only part of the story. Jurassic forests were probably acoustically crowded, with many species calling at once. In that setting, insects may have evolved ultrasound partly to avoid being overheard and partly to carve out a less competitive acoustic niche. So the best answer is that no bat-like superpredator was responsible. The likely drivers were early mammalian insect hunters, along with other eavesdropping predators and competition in a noisy Jurassic soundscape. The study does not identify a single specific predator species, but it strongly shifts the blame from bats to early mammals and broader ecological pressures.

3 articles · Updated · Sci.News · Aug 25

Twenty fossil insects from China’s 165-million-year-old Jiulongshan Formation let researchers reconstruct Jurassic calls from preserved wing structures using lasers, computer models, AI and comparisons with nearly 100 living species.
One species, Sigmaboilus peregrinus, appears to have called above 20 kHz—ultrasonic and beyond human hearing—while most of the other nine analyzed species produced low pure-tone calls around 5 kHz.
That pushes the oldest known animal ultrasound communication back to the Middle Jurassic and undercuts the long-held idea that bats drove insects into the ultrasonic range, since bats emerged roughly 55 million years later.
The PNAS study instead points to early mammals, other predators and competition for acoustic space as likely pressures shaping diverse insect signaling in Jurassic forests.