We take it for granted that virtually every habitat on Earth is alive with the sounds of animals, from the haunting songs of whales in the oceans to the riotous symphony of birds, frogs and insects in forests to the hubbub of humans and our technological creations in cities the world over. Yet for most of our planet’s history the only sounds were those of the wind, rain and waves.
The oldest-known putative insect dates to 408 million years ago and was probably soundless and deaf. Scientists do not know exactly when insects started to first make or hear sounds, but the fossil record provides a minimum date: a katydid from around 250 million years ago has the sound-producing anatomy characteristic of this group. The earliest-known fossils of cicada relatives also date to this time.
Among the most acoustically talented animals in the Mesozoic were the dinosaurs. In 1981 David Weishampel carried out one of the first reconstructions of a fossil animal’s vocalization, working with the herbivorous, duck-billed dinosaur Parasaurolophus. This creature had a giant crest on its head that connected to its airway. Weishampel demonstrated that the crest made for an excellent resonating chamber.
For short-necked animals, including humans, the resulting delay in signal speed is trivial. But for a giant, long-necked dinosaur, this delay would be comparatively enormous—so much so, in fact, that there would be no way to properly control the rapid movement of the vocal cords during complex vocalizations such as honking or trumpeting. The next time you watch Jurassic Park, imagine honking hadrosaurs, trumpeting tyrannosaurs and hissing brachiosaurs.
Interestingly, the other vertebrate fliers of the Mesozoic, the pterosaurs, did not have a syrinx. So contrary to what Hollywood might have us believe, pterosaurs did not sound like birds. They probably sounded more like other reptiles. They might have growled, hissed, clicked or even bill clacked, opening and closing their beaks to make a clattering sound.
The evolution of echolocation in bats marked a major ecological revolution: vertebrates could now hunt insects on the wing in total darkness. After 275 million years, flying insects had nowhere to hide. Bats flourished as a result of this innovation. Today they make up roughly 25 percent of mammal species, and although some bats rely solely on vision to hunt, most of them echolocate.
Well I coulda told ya that.
!!!!!!!!
ravenscimaven It was the day beans were first discovered.
It is the Americans who r destroying the nature
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