The love song of an extinct katydid that lived 165 million years ago has been brought back to life, according to a study in the latest issue of PNAS. The song is thought to be the most ancient known music documented to date.

The song was reconstructed from microscopic wing features on a fossil discovered in North East China. It allows us to listen to one of the sounds that would have been heard by dinosaurs and other creatures roaming Jurassic forests at night.

A veritable symphony of natural sounds must have filled the world 165 million years ago, with primitive crickets and croaking amphibians leading the way. These were among the first animals to produce loud sounds by stridulation, or rubbing certain body parts together. (We humans can do a version of this too, as this fellow demonstrates.)

Katydids produce mating calls by rubbing a row of teeth on one wing against an appendage on the other wing, but how their primitive ancestors produced sound and what their songs actually sounded like was unknown until now.

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The research began when a team of palaeontologists, including Jun-Jie Gu and Dong Ren from the Capital Normal University in Beijing, contacted Fernando Montealegre-Zapata and Daniel Robert, both experts in the biomechanics of singing and hearing in insects, in Bristol's School of Biological Sciences. The group also teamed up with Michael Engel of the University of Kansas, a leading expert on insect evolution.

The researchers from Beijing provided an exceptionally well preserved katydid fossil from the Mid Jurassic period. The specimen had such clearly defined wing features that the details of its stridulating organs were visible under an optical microscope. Such information has never been fully obtained before from insect fossils. It was identified as a new fossil species and named Archaboilus musicus by the Beijing-Kansas team.

The Bristol scientists examined the anatomical construction of the fossil's song apparatus, and compared it to 59 living katydid species. They concluded that this animal must have produced musical songs by broadcasting pure, single frequencies.

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"This discovery indicates that pure tone communication was already exploited by animals in the middle Jurassic, some 165 million years ago," Robert was quoted as saying in a press release. "For Archaboilus, as for living bushcricket (katydid) species, singing constitutes a key component of mate attraction. Singing loud and clear advertises the presence, location and quality of the singer, a message that females choose to respond to – or not."

He added, "Using a single tone, the male's call carries further and better, and therefore is likely to serenade more females. However, it also makes the male more conspicuous to predators if they have also evolved ears to eavesdrop on these mating calls."

The researchers believe that A. musicus sang a tone pitched at 6.4kHz and that every bout of singing lasted 16 milliseconds.

"Using a low-pitched song, A. musicus was acoustically adapted to long-distance communication in a lightly cluttered environment, such as a Jurassic forest," Montealegre-Zapata said. "Today, all species of katydids that use musical calls are nocturnal so musical calls in the Jurassic were also most likely an adaptation to nocturnal life. Being nocturnal, Archaboilus musicus probably escaped from diurnal predators like Archaeopterix, but it cannot be ruled out that Jurassic insectivorous mammals like Morganucodon and Dryolestes also listened to the calls of Archaboilus and preyed on them."

"This Jurassic bushcricket thus sheds light on the potential auditory capacity of other animals, and helps us learn a little more about the ambiance of a world long gone. It also suggests the evolutionary mechanisms that drove modern bushcrickets to develop ultrasonic signals for sexual pairing and for avoiding an increasingly relevant echolocating predator, but that only happened 100 million years later, possibly with the appearance of bats."

To hear the Jurassic love song, the world's oldest known music, Download Video_S1