We have their avian descendants to look at, as well as other large animals. That gives us a reasonable idea of the pitch/volume a dinosaur might have.

But it is important to remember that there is no guarantee. The things you see in a fossil are not even close to the whole picture.

[removed]

They don't. They can only guess. As far as I know, no dinosaur fossil has ever been found with a hyoid bone, which is part of how we're able to make noise and speak. That doesn't mean they couldn't make sounds. It's quite likely they could, at least some of them. Think less high pitched chirping ala birds today, and more hissing, rumbling, and trumpeting.

The thing is that they don't know. It's a puzzle with some educated guesses, based on some facts that they have managed to shake out of the dirt.

You see, dinosaurs and their skeletons have a lot of similarities to birds. Which means that you can make the educated - but difficult to prove or disprove - guess that a dinosaur would sound like a really huge bird.

Just by comparing a sparrow's sound to the sound of an ostrich, you get a hint of how size changes the sound. Apply similar reasoning to the size difference between an ostrich and a large dinosaur...and there IS a chance that they actually sounded kind of like it's pictured in a lot of movies.

Do we know for sure? No. Of course not. We cannot know for sure.

But guessing is fun too, when other scientists agrees that your guesses are not completely stupid.

IIRC for some dinosaurs they know that their heads had cavities that would have acted as resonators, thus shaping the sounds they produce.

Dinosaurs most likely had a Syrinx, just like their bird descendants. And a syrinx is much more capable of making a wide variety of noises (and it generally does not involve the hyoid bones) than the mammal larynx.

As for modern birds "chirping". Modern birds have a very wide variety of sounds they can make. Take an ostrich for example and google what kind of sounds they can make (make sure to google ostrich mating call since many results don't bring that up).

Or google lyre birds if you really want to know the capabilities of a birds syrinx when it comes to generating sounds.

I'm too lazy to look it up, but I read an article years ago where they took a skull that had been 3d printed off of scans, plugged the holes that would have been blocked by tissue, and blew air through it. They immediately got sounds, so it was definitely shaped as a resonating chamber.

They don't, and I've never heard one confidently say they did.

Educated guesses based on what they do know and what they think they know about behavior, anatomy, etc. are common and often proven right and proven wrong by later research.

This is true, also general size of chest cavity etc. But they don't know much else. There could be all kinds of obstructive tissue, convoluted airflow pathways, muscular limitations and just about any other barrier you can imagine. It's entirely possible for a big barrel chest and other appropriate anatomy to produce a cute little whistle or some kind of baby dinosaur from a Hollywood movie trill.

> make sure to google ostrich mating call

Just did, can recommend :D (Link for the lazy among you)

[removed]