No one on Earth has ever heard a dinosaur roar. But that hasn’t stopped scientists and filmmakers from wondering: what did dinosaurs look like?
The most famous answer might come from the movie jurassic parkwhich featured dinosaur roars that sounded like this:
It’s a scary noise, but it’s probably not realistic. Dinosaurs were reptiles, but when the jurassic park The sound designers created their roars, they built them mainly from the sounds of mammals – from recordings of tigers, lions, koalas (!), donkeys, dolphins and elephants.
There is no scientific basis for a T. rex to sound like a donkey. Instead, the filmmakers were trying to evoke the feeling to be in the presence of a dinosaur. (jurassic park Sound designer Gary Rydstrom once responded to a scientist’s critical question about the film by laughing and saying, “It’s a movie. “)
Figuring out what the dinosaurs actually looked like is a nearly impossible task, as scientists can’t exactly unearth a fossilized roar. “Most sound-producing structures are soft tissue or less resilient hard tissue,” says paleontologist Michael Habib. Inexplicable, Vox’s science podcast on unanswered questions. “It’s muscle and cartilage, and those tend not to fossilize.”
Still, scientists think it’s an important question. Understanding what dinosaurs looked like means understanding a little better the world they lived in and is essential to understanding how they behaved.
For starters, the shapes of dinosaur skeletons provide some tricks. A dinosaur, called Parasaurolophus (aka Ducky’s The land before time), had a long chamber in its skull, which allowed scientists to estimate general frequencies that might have been resonating in its head. But this room doesn’t tell us about the true voice of the dinosaur that fueled it.
However, all hope is not lost. In order to understand what a real dinosaur voice might sound like, scientists can turn to living relatives of dinosaurs.
“We have to do our best,” Habib says, with the clues the scientists have. These are the most promising leads.
Crocodilians emit low-pitched growls. Maybe a T. rex too.
Scientists can turn to living relatives of dinosaurs to piece together their sounds. If they share a common ancestor, they may also have similar attributes, such as the way they make sounds.
One such related group is the crocodilians (crocodiles, alligators, caimans), which share a common ancestor with the dinosaurs that lived around 250 million years ago.
If you look jurassic parkyou’ll see a T. rex opening its mouth to roar, but if T. rex’s are more like crocodilians, they probably would have made more of a low-pitched, closed-mouth rumble.
“They rumble so powerfully that you see ripples all around them on the water,” Habib says of the crocodilians. “They’re shaking the pond, basically.”
Larger animals tend to make lower pitched sounds than smaller animals. So imagine a huge dinosaur, several times larger than a common crocodile; it’s possible that this dinosaur made a very low-pitched, closed-mouth crocodilian growl.
Paleontologist Julia Clarke demonstrated this with the BBC, throwing an alligator sound extremely far to simulate what a T. rex might have sounded like:
As the pitch decreases, it approaches the range known as infrasound. Just as infrared light is too long a wavelength for a human to usually see, infrasound waves vibrate so slowly that they can be difficult for a human to hear. So if dinosaurs sounded like an ultra-low pitched crocodilian, a lot of their sounds might have been hard to hear. The hairs on the ears are too small to vibrate from this sound, but larger parts of the body might have vibrated.
If a human was sent back in time, they could have felt the sound in their legs or chest. Creepy !
Birds are even closer to dinosaurs, so could dinosaurs have sung?
Crocodiles are a good starting point for imagining what dinosaurs might have looked like, but they are not the closest relatives of dinosaurs.
This honor goes to the birds, the direct descendants of the dinosaurs. “I used to put a roast chicken on the document viewer in the classroom,” says Clarke. “You can see the assembly of these structures that are in your roast chicken in the fossil record.”
So how can birds potentially teach us what dinosaurs looked like? Hint: birds have a unique vocal organ. Most vertebrates make sound using their larynx, a vocal organ located in the throat, but birds use a syrinx, a vocal organ located deep in the chest, next to the heart. Clarke likes to joke, “Birds sing from the heart.”
Because a syrinx is located deep in the chest, it produces sound more efficiently, which is why small birds can make such loud noises. Also, unlike a larynx, a syrinx actually has two openings, so birds can produce multiple pitches at once. “They can sing a duet with themselves,” says Habib. The wood thrush, for example, does this by singing two notes at the same time.
But if birds are actually tiny dinosaurs, why consider the sounds of crocodilians? The problem is that scientists don’t know when syrinxes first appeared. Clarke found a syrinx from 67 million years ago (about a million years before the extinction of the large dinosaurs), but this syrinx came from an ancient duck relative, not from a huge dinosaur. She has yet to find concrete evidence of a huge dinosaur with a syrinx.
But because syrinxes are soft structures, it’s hard to find evidence for them. (Clarke’s syrinx was an extremely rare find.) So it’s possible that there are other, even older syrinxes, waiting to be unearthed.
Dinosaurs singing a duet with themselves?
If scientists confirmed that dinosaurs had syrinxes, it would open up a world of sonic possibilities. Dinosaurs might have looked like large flightless birds like ostriches or emus, which can produce all sorts of whistles, guttural hisses and throat-clapping.
But the bigger a dinosaur, the weirder it would have seemed. Habib describes a huge potential dinosaur syrinx sound as a “tuba honk”. “It’s like an impulse,” he says. “A very weak sound. Bruhhhhhm, bruhhhhhm, bruhhhhhm. Habib made this noise to me on the phone:
But wait. It can get much weirder. A syrinx would have allowed a dinosaur to make two sounds at once, so Habib can really let his imagination run wild: “Take two snorkels. And have them play different notes on top of each other as loudly as possible. It’s just that kind of rumble of war.
It’s also possible that the dinosaurs looked like a mixture of birds and crocodilians. Habib says they could have made open-mouthed bird-like sounds and closed-mouthed crocodilian sounds together.
Here is what he imagines:
They could make open-mouthed sounds with two different tones, and then could also make closed-mouthed sounds that would be a rumble. And they could switch between the two, which means they could rumble, and while your body is still shaking from the rumble, they can open their mouths and blast you with two non-infrasonic but still very low notes, while things are always kind to shiver from the rumble. It could get very interesting.
Habib is quick to warn that because we don’t know if the massive dinosaurs had syrinxes, this is all speculative. “The most conservative estimate would be to use crocodilian-based sounds” to imagine dinosaurs, he says. “But the best is probably a careful combination of all of the above.”
In this week’s episode of Inexplicable, Vox sound designer Cristian Ayala tried his hand at creating scientifically plausible dinosaur sounds based on these conversations. Here’s his process for putting together a new T. rex sound, based on what we’ve learned from paleontologists.
He started with the “b’caw” of a chicken, poked it, and added the sound of a sandpiper (and Inexplicable producer Mandy Nguyen’s pigeon, Sunny), layering noises at different frequencies on top of each other. There is a little tuba influence and some ostrich, emu and alligator sounds as well.
Was this what a T. rex actually looked like? Nobody knows!
But it’s likely to be a more accurate representation than what you’ll hear in jurassic park. The scientists I spoke to emphasized that this exercise is more than just child’s play. Sound is important because it shows how ancient animals communicated, how they moved, how they lived. Scientists may never know exactly what this world looked like, but by trying to recreate dinosaur sounds, they can imagine, if only a little better, the world these creatures lived in.