Karela Fry

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A Jurassic sound

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Jun-Jie Gu and friends report in PNAS:

Behaviors are challenging to reconstruct for extinct species, particularly the nature and origins of acoustic communication. Here we unravel the song of Archaboilus musicus [Gu, Engel and Ren sp. nov.], a 165 million year old stridulating katydid. From the exceptionally preserved morphology of its stridulatory apparatus in the forewings and phylogenetic comparison with extant species, we reveal that A. musicus radiated pure-tone (musical) songs using a resonant mechanismtuned at a frequency of 6.4 kHz. Contrary to previous scenarios, musical songs were an early innovation, preceding the broad-bandwidth songs of extant katydids. Providing an accurate insight into paleoacoustic ecology, the low-frequency musical song of A. musicus was well-adapted to communication in the lightly cluttered environment of the mid-Jurassic forest produced by coniferous trees and giant ferns, suggesting that reptilian, amphibian, and mammalian insectivores could have also heard A. musicus’ song.

If you need help decoding that, then look no further than the BBC:

Scientists from the US and China discovered the tiny fossil and named their newly discovered species Archaboilus musicus , because the music-making structures in its body were so clearly visible.

When insect expert Dr Fernando Montealegre Zapata, from the University of Bristol, found out that his colleagues had such a remarkable fossil, he was keen to see it.

“I was very surprised,” he told BBC Nature, “because those [structures] are very very small – at the microscopic level.”

Dr Zapata studies sound production and communication in living insects, working out how the musical instruments contained in many insects’ bodies produce a particular sound, and exactly how that sound is made.

He immediately asked the question: “Could we reproduce the sounds [this insect made] from that fossil?”

Just like modern bush crickets – also known as katydids – the Jurassic insects produced music with their wings. A “plectrum” on one wing was dragged along a microscopic comb-like structure on the other.

This produces a continuous “chirp” as the male insects rub, or “stridulate” their wings in a scissor-like motion. Dr Zapata described this stridulation as similar to playing a tiny violin.

By looking at the wing structures, he explained, “I could estimate that the animal made pure, musical tones”.

Such a single-note tone would have transmitted efficiently – a regular wave of sound penetrating a noisy environment cluttered with vegetation. This would have allowed a female cricket to detect a male’s song from tens of metres away.

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Written by Arhopala Bazaloides

February 10, 2012 at 5:34 pm

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