Was T. Rex Scaly — or Fluffy?

Any dino lover can picture a Tyrannosaurus rex. After all, the massive meat-eater is one of the most popular dinosaurs — and the star of blockbuster movies. T. rex was a scaly, brownish-gray giant whose loud roar could rumble the Earth and drown out an entire pride of lions, right?

Probably not.

The “king of the tyrant lizards” — that’s what “Tyrannosaurus rex” means — more likely had a mullet of fluffy, maybe even colorful feathers on its head, neck and tail. And those loud roars? Forget about them. T. rex probably made deep booming, honking or grunting sounds like a modern-day emu.

How could we have been so wrong for so long about what T. rex was like? The short answer is: We didn’t know any better. Up through the 1980s, T. rex skeletons were pretty rare finds, so we didn’t have much to go on. When there’s not much evidence, scientists have to figure things out based on what they already know.

Until the 1840s, nobody knew that any dinosaurs had ever existed. So a huge bone discovered in the 1670s was believed to have come from a man — a giant man! Bird-like tracks found in the early 1800s were called the “tracks of Noah’s raven,” referring to the biblical account of Noah sending out birds in search of dry land. And large tooth-shaped fossils discovered in 1822 were identified as coming from something like a super-sized iguana. Wrong, wrong, wrong.

By 1841, British scientist Richard Owen realized that these fossils had come from extinct animals the likes of which we’d never seen before. He named them “Dinosauria,” which means “terrible lizards.”

Figuring out exactly how these ancient animals looked or moved around was difficult. Paleontologists, the scientists who study life long ago, learn a lot by studying fossils and comparing their anatomy to other, living animals with similar features. But through the mid-1900s, they had few fossils to study. Based on the bits of discovered dinosaur skeletons and their knowledge of reptiles, early paleontologists believed dinosaurs plodded along with their tails dragging behind them. In fact, dinosaurs seemed so ill-suited to life on Earth that scientists initially believed they died out on their own. (Now we know a massive asteroid impact led to their extinction.)

Early depictions of T. rex—even in famous natural science museums — fit this image. In art and exhibits, the dinosaurs were posed standing upright with their tails dragging on the ground like monstrous kangaroos. (And before a complete T. rex skull was found, their heads and mouths were drawn ridiculously small, too.)

In the 1960s and ’70s, some paleontologists began to realize that they had gotten T. rex really wrong. The king of the tyrant lizards would not be able to hold itself upright without dislocating its hips and maybe even breaking some tail bones. Scientists began to think that, instead of being colossal, cold-blooded, lumbering lizards, dinosaurs probably were warm-blooded and more bird-like: agile and lively — but way more ferocious. They realized that T. rex moved in a stalking posture with its body nearly parallel to the ground and its long tail suspended in air to balance its huge, fearsome head. Museums everywhere had to change their exhibits.

Since the early 1990s, paleontologists have discovered many more dinosaur fossils, including another dozen T. rex skeletons and several other tyrannosaur relatives. They also gained a better understanding of evolution and comparative anatomy — knowing how joints can and cannot move in any animal — and what life was like during the Mesozoic Era when dinosaurs lived. Scientists also developed new tools to study dinosaurs. They made 3D scans of fossil bones and used computers to learn more about how the dinosaurs were put together and might be able to move.

Still, for more than a century, scientists had little evidence suggesting that dinosaurs looked much different from their scaly reptilian relatives on the outside. Soft tissues, including skin, decompose quickly after an animal dies and rarely get preserved in fossils. But in the 1990s, paleontologists in China found a treasure trove of amazingly well preserved fossils that changed our entire understanding of dinosaurs.

Many dinosaurs had feathers! Paleontologists found feathers not just on the little avian dinosaurs that evolved into today’s birds but even on ferocious tyrannosaurs — though nobody found a T. rex fossil with feathers (yet). Not that they haven’t tried. Some paleontologists examined fossilized impressions of an adult T. rex’s skin from parts of its stomach, chest, neck, pelvis, and tail. It was scaly. Period. No traces of feathers.

Does that mean that T. rex was not one of our feathered friends? Nope.

Scientists believe that a T. rex baby, which was about the size of a small turkey, had an entire coat of downy feathers to keep it warm. But as it grew bigger — which it did at an alarmingly fast rate — the little fluff ball lost most of its feathers. By the time a T. rex was fully grown, it was mainly scaly.

To figure this out, scientists relied not just on the fossils they found but also on their understanding of evolution and how animals adapt to their environments. T. rex evolved to be much bigger than its predecessors, and — like other big animals — it undoubtedly got hot when it dashed to catch its next dinner. Having a full coat of feathers would have been a disadvantage, because it would not have let the T. rex cool down.

But T. rex was hardly bald. It still sported patches of feathers on its head, neck, tail and maybe back. Those feathers were just for show. Like modern birds—which are considered “avian dinosaurs”—many dinosaurs long ago used displays to attract their mates. They showed off their flashy feathers and their best dance moves. (And they made sounds much more like bird-like booms and grunts than lion roars.)

T. rex was probably no exception. It likely flaunted its feathers by waving its tail and even prancing around like a bird. That’s quite a different depiction from the lumbering lizard of the 1800s!