What did a Jurassic forest sound like? Scientists recreate 165-million-year-old insect calls and make a startling discovery with AI, lasers and fossil wings

For roughly 165 million years, the soundscape of the Jurassic remained completely silent to modern ears. Dinosaurs, early mammals and countless insects once shared prehistoric forests, but while fossils can preserve bones and even delicate body structures, the sounds those creatures made seemed impossible to recover.

Now, scientists have found a way to bring part of that lost acoustic world back.

Using fossilised insect wings, experiments on living species, computer simulations and artificial intelligence, researchers have reconstructed the calls of nine extinct insects that lived during the Jurassic Period. The results provide what scientists describe as one of the most detailed evidence-based attempts yet to recreate the sound of an ancient ecosystem.


The study, published August 25 in the Proceedings of the National Academy of Sciences, examined 20 fossil specimens discovered in Inner Mongolia, China. The fossils belonged to insects related to modern crickets and katydids and preserved crucial features of their sound-producing wings.

But one discovery has attracted particular attention: at least one Jurassic insect may have communicated using sounds at frequencies reaching beyond the upper limit of human hearing.

A Jurassic forest may have been filled with insect calls

The insects examined in the study belonged to nine extinct species. Their fossilised wings retained structures that acted much like the sound-producing mechanisms found in some insects alive today.

Modern crickets, katydids and grasshoppers do not make their characteristic calls using vocal cords. Instead, many produce sound through stridulation, a process in which specialised body surfaces are rubbed against one another.

The same basic principle appears to have existed among some of their Jurassic relatives.

Researchers found evidence of ridged, comb-like structures on one wing and a scraping structure on the other. As the wings moved against each other, the scraper could catch the ridges in rapid succession, creating a series of vibrations that would have been perceived as a chirping sound.

The precise design of those structures mattered.

The spacing and number of ridges, as well as the size and shape of the vibrating parts of the wing, could influence the frequency and character of the resulting sound. In other words, the fossils did not merely reveal what these insects looked like — they preserved parts of the biological machinery that once made them audible.

That gave scientists an unusual opportunity to work backwards from anatomy to sound.

Scientists used living insects to solve an ancient mystery

Reconstructing a sound that disappeared more than 100 million years ago is not as simple as putting a fossil into a computer and pressing play.

The researchers first examined living insects to understand how comparable sound-producing structures behave.

High-speed cameras were used to capture wing movements during stridulation. Scientists also employed laser Doppler vibrometry, a technique that can measure extremely small vibrations, to determine how the wings moved as the insects produced sound.

Those observations helped researchers develop and test computer models showing how different wing structures translate into different acoustic signals.

The fossil wings were then converted into two-dimensional models. Their physical characteristics were incorporated into the simulations, while the evolutionary relationships between the extinct insects and their modern relatives were also taken into account.

Artificial intelligence and machine-learning techniques helped analyse the resulting patterns and estimate what the ancient insects' calls may have sounded like.

The process ultimately produced reconstructed calls for all nine species.

Most Jurassic insect calls were around 5 kHz

The reconstructed sounds suggest that many of these Jurassic insects produced relatively low-frequency calls.

Several were estimated to have called at roughly 5 kilohertz, placing them in a range comparable to the sounds produced by some modern crickets.

Rather than complex musical patterns, many of the reconstructed signals appear to have been relatively simple, with much of their energy concentrated around a single frequency. Scientists describe these as “pure tone” calls.

To modern listeners, the result would likely resemble clear, high-pitched chirps.

That finding offers a fascinating glimpse into what an ordinary Jurassic forest might have sounded like. The roar of large animals may have dominated parts of the landscape, but beneath it could have been a constant layer of insect communication.

One Jurassic insect may have called above 20 kHz

The most surprising result came from Sigmaboilus peregrinus.

Computer reconstruction suggests that this insect may have produced sounds between 20 and 22 kilohertz. For humans, that sits at or just beyond the upper boundary of normal hearing.

Human hearing is generally considered to extend from about 20 hertz to 20 kilohertz, although the precise upper limit varies between individuals and typically declines with age.

If the reconstruction is accurate, S. peregrinus may therefore have been capable of producing ultrasonic or near-ultrasonic signals long before bats appeared.

That possibility is significant because it challenges one popular explanation for the evolution of ultrasonic communication among insects.

Jurassic insects may have gone ultrasonic before bats appeared

One established idea is that insects evolved very high-frequency communication partly in response to bats.

Bats are highly effective predators of flying insects and use ultrasonic echolocation to detect prey. High-frequency insect communication may therefore have evolved alongside this predator-prey relationship.

There is one major problem with applying that explanation to these fossils.

Bats appeared much later than the Jurassic Period.

The insects reconstructed in the new study lived roughly 165 million years ago, while bats emerged around 100 million years after the Jurassic ended. Early bats therefore could not have driven the evolution of ultrasonic communication in these insects.

The researchers suggest several alternative possibilities.

High-frequency signals may have helped the insects communicate in an environment filled with other sounds. If numerous species were calling at similar frequencies, shifting to another frequency range could have made individual signals easier to recognise.

The insects may effectively have occupied different acoustic “channels”.

That could mean the Jurassic insect community already had a surprisingly sophisticated acoustic structure, with different species communicating at different frequencies.

Fossils could reveal a lost prehistoric orchestra

The study demonstrates how much information can survive in a fossil beyond the obvious shape of an extinct animal.

While soft tissues and behaviours are usually lost, insects have an advantage: their hard external skeletons can preserve specialised structures with remarkable detail.

Those structures can contain clues about how an insect sensed its surroundings or interacted with others.

Scientists now believe similar methods could potentially be applied to other extinct insects. Ancient beetles, ants and other groups may also have possessed specialised structures capable of leaving enough evidence for researchers to reconstruct aspects of their communication.

Artificial intelligence could make that process increasingly powerful by helping scientists compare fossil structures with living species and model how those anatomical features translated into sound.

The researchers describe the possibility as uncovering a kind of “paleo-orchestra” hidden inside ancient fossils.

What did the Jurassic really sound like?

The reconstructed insect calls could also change the way the Jurassic is portrayed in documentaries and popular science.

The research team collaborated with the creators of the Netflix documentary miniseries The Dinosaurs, providing reconstructed insect sounds for Jurassic sequences.

The addition may seem minor compared with recreating enormous dinosaurs, but it addresses an important problem with recreating extinct worlds: prehistoric landscapes should not sound like modern forests with dinosaurs digitally added.

Insects were an important part of those ecosystems, and their calls would have contributed to the background soundscape.

The new research cannot tell us exactly what a Jurassic forest sounded like. Computer reconstructions necessarily involve assumptions, and the original insects and their environments are gone.

But the study brings scientists closer than ever to hearing a small part of that vanished world — and suggests that 165 million years ago, prehistoric insects may already have been communicating across a surprisingly complex range of frequencies.