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February 06, 2012

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Scientists reconstruct cricket sound from dinosaur age

Feb. 5, 2012
Courtesy of the University of Bristol
and World Science staff

A clean, high-pitched “ping” or chirp seems to pierce the air when you re­play a re­con­struc­tion by sci­en­tists of a crick­et’s song from the di­no­saur age.

Chin­ese pa­le­on­tol­ogists de­vel­oped the new recrea­t­ion to­geth­er with ex­pe­rts on in­sect song, us­ing in­forma­t­ion from a fos­sil. They have posted a vi­deo­clip on the Web dem­on­strat­ing the re­sult­ing sounds. Pos­sibly the most an­cient known song doc­u­mented to date, it’s some­thing that Ju­ras­sic di­no­saurs might well have heard in the for­est back­ground at night, they say.

To play the re­con­struct­ed crick­et song, you need to have Ap­ple's Quick­Time Play­er  (click to down­load. Some brow­s­ers will also re­quire that the whole vi­deo be down­loaded be­fore it can be played). The song was pro­cessed to take into ac­count slight echoes pro­duced by the light­ly clut­tered en­vi­ron­ment of con­i­fer­ous trees and gi­ant ferns.

A clean, high-pitched “ping” or chirp seems to pierce the air when you replay a reconstruction by scientists of a cricket’s song from the dinosaur age. Chinese paleontologists developed the new recreation together with experts on insect song, using information from a fossil. They have posted a video clip on the Web demonstrating the resulting sounds. Possibly the most ancient known song documented to date, it’s something that Jurassic dinosaurs might well have heard in the forest background at night, they say. A variety of sounds enlivened ancient woodlands some 165 million years ago, in the mid-Jurassic period, scientists say. Primitive bush-crickets and croaking amphibians were among the first animals to produce loud sounds by stridulation (rubbing certain body parts together). Modern-day bush-crickets – also known as katydids – produce mating calls by rubbing a row of teeth on one wing against a structure called a plectrum on the other wing. But how their primitive ancestors made sounds and what these sounded like has been unknown. On discovering several insect fossils, Chinese palaeontologists including Jun-Jie Gu and Dong Ren of Capital Normal University in Beijing contacted Fernando Montealegre-Zapata and Daniel Robert, experts in the biomechanics of singing and hearing in insects, in Bristol’s School of Biological Sciences in the U.K. They also teamed up with insect evolution specialist Michael Engel of the University of Kansas. The Chinese group provided a bush-cricket fossil from northeastern China so well preserved, the stridulating wing structures were clearly visible under a microscope. It was identified as a new fossil species and named Archaboilus musicus. Montealegre-Zapata and Robert examined the song apparatus and compared it to 59 living bushcricket species. They concluded the insect must have broadcast pure, single notes. “This discovery indicates that pure-tone communication was already exploited by animals in the middle Jurassic, some 165 million years ago,” Robert said. “For Archaboilus, as for living bushcricket 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. 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 scientists say the research, published today in the research journal PNAS, implies that the acoustic environment was already quite busy, with many animals singing at the same time, possibly chorusing, joining additional noise from waterfalls, streams and wind. Following biomechanical principles that he said he discovered some years ago, Montealegre-Zapata concluded that A. musicus sang a tone with a pitch measured at 6,400 Hertz, or vibrations per second. That’s higher than what a piano can play (it would take four additional white keys to the right of the rightmost note on a standard piano keyboard, reaching a high “G,” to approximate the insect’s pitch.) The researcher also concluded that each tone lasts just 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,” he added. “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,” he went on. “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.”