In the movies, we often hear dinosaurs let out big, scary sounds. If you've ever played with toy dinosaurs, maybe you've also made your little Tyrannosaurus rex roar.
While dinosaurs have a reputation for roaring, I wasn't entirely certain whether or not they actually did so in real life. I asked my friend, Washington State University professor Cynthia Faux.
Examining an animal's voice box might give us clues about what kind of sound it made. There are lots of birds on our planet and they all have different tweets, caws and chirps. Of course, a dinosaur's voice box would have been much bigger than a bird's voice box.
Sometimes, when we want to learn about life in the past, we examine fossils. Fossils are preserved traces of plants and animals. Some scientists even study poop fossils to find out what animals ate. But not all parts of an animal can be traced through fossils. Some voice boxes are made up of soft tissue.
This soft tissue breaks down over time, which makes it hard to figure out exactly what kind of voice box a dinosaur used to make their sounds.
Scientists who conducted some of the most recent research into dinosaur sounds have found the creatures actually might have cooed or boomed. In fact, that sound may been similar to the kinds of noises today's emus or ostriches make, Faux said.
Roaring is also more of a mammal thing, Faux added. Lions, tigers and bears are all predators that roar - but they aren't roaring all the time. When they do roar, it's often to show their dominance or to scare away another animal.
After all, making a lot of sound when you approach your prey isn't the brightest idea. It works much better to quietly sneak up on your prey, so they don't know what's coming.
There may have been some other ways dinosaurs communicated, too. Some dinosaurs may have displayed their feathers. Yes, some dinosaurs had feathers. They may have used them as a way to send messages to those around them-perhaps as a defense or to attract a mate.
Sauropods - plant-eating, four-legged dinosaurs that usually had long necks - were as big as houses and made a lot of noise just by walking around. Perhaps their stomping sent a message to those around them.
Some dinosaurs may have communicated in a way similar to alligators. By creating vibrations in the water, they could let creatures around them know they are frightened and might strike.
Alligators, birds and all kinds of animals make interesting sounds on our planet these days. Can you hear any animal sounds in your neighborhood? Can you guess what animal is making the sounds you hear?