BBC reports on new research reconstructing the sounds of the dinosaurs, the honks, hoots, chirps, and vibrating grunts that the giant creatures used to communicate millions of years ago:
Some dinosaurs had greatly elongated necks – up to 16m (52ft) long in the largest sauropods – which would have likely altered the sounds they produced (think about what happens when a trombone is extended). Others had bizarre skull structures that, much like wind instruments, could have amplified and altered the tone the animals produced. One such creature, a herbivorous hadrosaur named Parasaurolophus tubicen…had an enormous crest almost 1m (3.2ft) long protruding from the back of its head. Inside this were three pairs of hollow tubes running from the nose to the top of the crest, where two of the pairs performed a U-bend to wind back down towards the base of the skull and the animal’s airways. The other pair widened to form a large chamber near the top of the crest. In total they formed what was essentially a 2.9m (9.5ft) long resonating chamber.
In 1995, palaeontologists at the New Mexico Museum of Natural History and Science unearthed a nearly complete skull of this unusual looking Parasaurolophus. Using a computerised tomography (CT) scanner, they were able to take 350 images of the crest, allowing them to see inside in unprecedented detail. Then, working with computer scientists, they digitally reconstructed the organ and simulated how it might behave if air was blown through it.
“I would describe the sound as otherworldly,” says Tom Williamson, one of those who worked on the dig and is now curator of palaeontology at the museum. “It sent chills through my spine, I remember.”
The closest analogues he can find in living animals today are the vibrating grunts of the southern cassowary, which lives in Australia. This flightless bird emits a series of deep bellows and growls that reverberate through the thick jungle where they live.
“It’s easy for me to imagine a misty Late Cretaceous rainforest setting with those eerie sounds thundering in the background,” says Williamson. “The sounds are of low frequencies – just what is necessary to penetrate the dense undergrowth.”
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Not all dinosaurs were blessed with what amounted to a trumpet atop their heads. And we have no fossilised evidence of voice boxes from dinosaurs, leading some to speculate the animals may even have been mute.
“What we do have are fossil clues that can tell us about different parameters of the airways like its diameter and its length,” says Julia Clarke, a palaeontologist at the University of Texas at Austin. “We can compare those geometries to see how they relate to those dinosaurs that are living today – birds.”
But Clarke has another clue that has provided a further piece of the puzzle. In the mid-2000s, she and her colleagues conducted a detailed examination of the preserved skeleton of an early type of bird found over a decade earlier by Argentinian researchers on Vega Island, a tiny scrap of land on the tip of the Antarctic Peninsula. The fossil itself remains partially embedded in a piece of rock, but using advanced CT scanning techniques, Clarke and her team were able to detect bits of the fossil hidden from view. They then digitally reconstructed the fossil from the scans.
And there, nestled amongst the fossilised bone fragments, were the remnants of something astonishing – the mineralised rings of a syrinx, the sound producing organ found in birds, dating back to the time of the dinosaurs.The primitive bird it belonged to – a goose-like creature called Vegavis iaai – would have coexisted with non-avian dinosaurs at the end of the Cretaceous period, 66-68 million years ago. At around this time, this part of modern Antarctica would have been covered in temperate forests and surrounded by shallow seas. The honking sounds of V. iaai were probably part of that landscape.
But for Clarke, the discovery reveals something else by its presence – that these sound-producing organs can fossilise, and their absence from most dinosaur fossils is telling.
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Her work has led her to a revelation that will shake the ground from under the feet of five-year-olds and movie goers around the world. Dinosaurs almost certainly didn’t roar. They probably cooed instead.
Or more accurately they may have produced sounds in ways similar to the way doves coo or ostriches boom. Many modern birds use what is known as closed-mouth vocalisation, where sound is made by inflating the throat rather than passing air through the syrinx. Crocodiles – another distant relative of the dinosaurs that split from a common ancestor around 240 million years ago – also use closed-mouth vocalisation to generate deep rumbles that can cause the water around them to “dance” around their bodies. Crocodiles, like other reptiles and mammals, have a larynx rather than a syrinx that produces the sound. But they bypass this when producing their mating bellows.
“The Jurassic Park films have got it wrong,” laughs Clarke.
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“The cochlear elongation denoting sensitivity to squeaky noises occurred near the origin of the archosaurian ‘ruling reptiles’, which includes birds and crocodiles,” says Bhart-Anjan Bhullar, associate curator of vertebrate paleontology at Peabody Museum of Natural History, Yale University, in New Haven, Connecticut…
“Given that baby birds and baby crocodiles chirp, it’s reasonable to infer that baby non-bird dinosaurs did as well, and that their parents listened to them and cared for them just as crocodile and bird parents do,” he says.