NANJING, Dec. 13 (Xinhua) -- Paleontologists from China, France, Germany and other countries have restored the ancient soundscape of katydids based on numerous insect fossils, and their research indicates that katydids likely hold the oldest record of high-pitched chirping among all animals.
As early as 240 million years ago, katydids had already evolved to produce a wide range of chirp frequencies. The sounds of the ancient katydids varied from 4 kilohertz -- close to the highest piano key -- to about 16 kilohertz, which is near the upper limit of audible to humans, according to Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
The team of researchers also tried to reconstruct the acoustic signals in ancient forests. "We believe that sounds of insects dominated the soundscape of forests more than 200 million years ago. Around 160 million to 180 million years ago, frogs and birds began to join the 'forest symphony,'" said Wang Bo, a researcher at the institute who led the study.
"The forest symphony has become increasingly complicated and closer to that of modern forests, as an increasing number of animal species capable of making sounds appeared about 100 million years ago," Wang added.
The international team of paleontologists built a fossil morphology database of over 1,000 fossil katydids that lived about 100 to 240 million years ago on the earth. They also found that the male katydids have been able to convey information including territorial competition and courtship by means of singing as early as 160 million years ago.
The findings were recently published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). ■
