Instead, the scientists noticed that the dinosaur nasal passages appear to have evolved separately from the external crests, taking on shapes that were not just a by-product of the outward crests. "This tells us that the nasal passages of the crests had an important function in addition to visual display," Evans explained. The researchers also witnessed a scientific first -- the world's first look at the inner ear structure of a lambeosaur. "It confirms that they could likely have heard the types of sounds that could have been made by the crests," says Evans, who believes the noises were deep, eerie and bellowing. Prior computer modeling supports that theory. He and his team detected the crests, nasal passages and inner ears in both male and female crested duck-billed dinosaurs, suggesting that all of these animals may have accompanied their visual displays with noise. Evans mentioned that duck-billed dinosaurs without complicated crests possessed similar inner ears, so they at least likely heard such sounds, and might have produced them too. Duck-billed dinosaurs may even have a modern-day counterpart in sound production. Earlier research suggests that cassowaries, extant flightless birds that can weigh up to 125 pounds, use their helmet-like bony casque to help produce low, "booming" calls. "When close to the bird, these calls can be heard or felt as an unsettling sensation, similar to how observers describe elephant vocalizations," said Andrew Mack, who led the study for the Wildlife Conservation Society. Mack said, "These investigations are exciting because many dinosaur fossils exhibit casques at least superficially similar to those of living cassowaries." Evans added that living crocodilians also possess inner ears that are comparable to those of the duck-billed dinosaurs. Somewhat similar to cassowaries, crocodiles and alligators produce very low, rumbling calls, sounds that may have been common during the Dinosaur Age. Related Links: |
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