What noise did dinosaurs make?
The sounds of dinosaurs roaring are arguably some of the most famous in pop culture. Almost anyone can identify the T.rex roar from Jurassic Park. It has often begged the question though...what did dinosaurs sound like?
Well, if you're looking for the short answer, it's frankly impossible to know without a time machine. As I have said in previous posts, fossilisation of a terrestrial vertebrate is extraordinarily rare to begin with. It is even rarer to find a nearly complete skeleton and a downright miracle for any soft tissue to be preserved. It's this soft tissue that will give the best estimates on any animal's sounds, so most vertebrates throughout Earth's history are, for all intents and purposes, mute.
Having said that, there are certain dinosaurs that are outliers. This could be either due to making sounds in a very specific way, indirect estimations inferred from other features, or even just weird coincidences. Let me elaborate.
A Quick Foreword...
Firstly, we need to ask why any animal actually needs to make a noise. The animals of todays world can be a noisy bunch, including many mammals, birds and especially...humans, so it's easy to imagine a world where dinosaurs are running around roaring at the top of their lungs all day long. However, making noise in the animal kingdom has very specific purposes and, in the wild, using this ability when it's not needed can be a detriment (again, not including humans I don't like or my cat at 3am). Whether or not you're the hunter or the hunted, alerting other animals about your presence isn't exactly the best the best idea since sliced bread.
So, why make any noise at all? Well, for the same reason we do: communication. Communication is a key part of many animals' lives and many use noise to do so. This could be for communicating with a pack/herd, part of a mating display or showing a rival/predator that you mean business.
There is also the fact that, from we can tell, dinosaurs likely lacked a larynx, since modern avian dinosaurs and crocodilians (their closest relatives) also lack them. This vocal organ is essential for creating that signature 'roar' that we hear in movies. Birds do have an alternative, however, known as a syrinx, which they use for their vocalisation.
With that out of the way, let's dive into some discussion as to what noises dinosaurs actually made.
An odd coincidence...
In paleontology, you'll often hear the phrase 'the present is a window into the past'. This couldn't ring more true here. Essentially, we'll never know for sure, but today's animals got their traits from somewhere, right? As I've said many times before, modern birds are scientifically classed as avian dinosaurs as they were the only group of theropods that survived the asteroid impact. Other than birds, the closest living relatives are crocodilians, so looking at the noises these animals make (and, just as importantly, why) can give us a good idea on what noises non-avian dinosaurs made.
This leads to some very strange coincidences. The best example is when we ponder what noise a dromaeosaur (the group commonly referred to as 'raptors') might have made. Dromaeosaurs were just about as close to a bird as you could get without actually being a bird, so the noises they made could have been fairly similar. But birds make so many different noises, so what one is the closest?
Well, whilst it might not have been remotely close, take a listen to the call of a Stellar's Sea Eagle and see if you can hear anything that reminds you of a certain toe-tapping dinosaur from a certain film...
Again, we don't have any reason to believe that this is what Velociraptor mongoliensis actually sounded like anymore than any other bird, but considering that the creators of Jurassic Park the sounds of an angry goose and tortoises making...smaller tortoises, it's a funny coincidence that they could have just recorded one of these beasts and gotten something very close!
Another bird call that makes it sound like your on a journey to the centre of the Earth is the call of the Channel-billed cuckoo.
Seriously it sounds like a a giant Azhdarchid is flying right above you...
An educated guess...
This brings us nicely on to how we can estimate the sounds of most non-avian dinosaurs, which is mostly through modern analogues. However, given the amount of variation in bird calls alone, this doesn't exactly narrow things down. To get a little more resolution, we need to take alternative approaches. We know that modern and extinct avian dinosaurs (birds) have evolved a syrinx, which serves the same function as a mammalian larynx, however, there isn't actually any evidence at the time of writing this that non-avian dinosaurs had the same organ, so it remains unlikely that they didn't.
What scientists have concluded with reasonable confidence, is that non-avian dinosaurs produced something called 'closed mouth vocalisation'. This type of vocalisation, as you may have guessed, doesn't involve opening the mouth, instead pushing air through their oesophagus whilst manipulating it. Extant animals that do this today include crocodilians, ostriches, pigeons and many others. So the sounds produced by the non-avian dinosaurs were likely closer to humming, cooing, croaking and hissing. These sounds could have been produced at great volumes with relative ease too, considering dinosaurs had the bird-like air sac respiratory system.
We can narrow it down even further if we think outside the box too. Evidence shows that there is a correlation between the pitch of the sound an animal produces and the animal's hearing range. With that in mind, we can look at cavities in the skulls of dinosaurs, showing the shape of their brain and ear cavities. We can see that many of the larger dinosaurs, namely sauropods and Tyrannosaurs, had an incredibly low hearing range. Considering that the only reason for these animals to make noise would be to communicate with (mostly) other members of the same species, we can reasonably conclude that animals such as T.rex and Apatosaurus also produced incredibly low frequency sounds. So low, in fact, that you likely wouldn't be able to hear them. This doesn't mean to say that the sounds were quiet though.
These dinosaurs would have been able to communicate with each other over many miles, since low frequency sound travels further, so whilst you may not have been able to necessarily hear the noise produced by a T.rex, you would have certainly felt it reverberating through you bones...which sounds much scarier to me...
As close as we can get...
Not all dinosaur sounds are lost forever though. The closest you'll ever get to actually hearing a dinosaur is thanks to Parasaurolophus walkeri.
That wonderful head crest has been long thought to serve the same function as the head crests seen on many other ornithopods, which is for display. However, a CT scan revealed that the inside of the crest had resonating chambers and tube similar to a trombone. After seeing this, paleontologists did the only logical thing and played various harmonics through a reconstruction of the crest, producing a variety of sounds that Parasaurolophus likely made.
Seriously, this thing is hauntingly beautiful...
So, whilst dinosaur sounds are never going to be 100% known without a time machine, leaps and bounds in paleontology have meant that the sounds of these awesome animals are much easier to imagine in real life.
Until next time!