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Why Don't Dinosaurs Have Ears?

We are used to seeing mammals every day. Mammals tend to have large, extravagant ears. In fact, many are known for their big ears—like elephants, cats, and bats!

But what about dinosaurs?  What did their ears look like?

There’s compelling evidence in the fossil record which shows that dinosaurs had inner ears and well-developed hearing. A great example comes from Sue, the famous Tyrannosaurus rex at The Field Museum in Chicago.  Researchers discovered that a tiny inner ear bone, called a stapes, had been preserved in the remains of this dinosaur. It’s a small bone that would have transmitted sound vibrations from the inner ear to the ear drum. Sue would have been able to hear the sounds of her Late Cretaceous environment.

Other evidence of dinosaur hearing comes from investigators utilizing new technologies to look at dinosaur remains. Using CT scanning equipment and 3D computer visualization paleontologists have been able to peer into the brain cavities of dinosaur fossils. From the size and shape of these brain cavities, they can make inferences about dinosaur hearing. Researchers have determined that some dinosaurs had large forebrains, which would lead to heightened senses of both hearing and smell.

So did dinosaurs have big outer ears?   

Ears are made of cartilage and skin, and these are soft tissues which typically do not preserve well in the fossil record. So paleontologists look closely at modern animals for answers. While mammals have large protruding ears, the closest living relatives of the dinosaurs, birds and reptiles, do not. So it seems very unlikely that dinosaurs would sport large floppy ears.

Birds have ear openings. These are holes just below and behind the eyes. Sometimes these ear opening can be quite large, but you just can't see them because they are covered in feathers. It seems likely that dinosaurs had the same type of ear openings, that may have also been covered in feathers.