The classic image of Tyrannosaurus rex is a reptilian monster. A green or brown, scale-covered brute that looks like an overgrown version of a crocodile or lizard. But in recent years, a new image has been making its way into books, television documentaries and online dinosaur palaeoart: a feather-covered T. rex.

Is this true?

First, there is not yet any direct fossil evidence of feathers on a T. rex. Nobody has found a T. rex skeleton cloaked in feathers, or any feathers sticking out of a T. rex arm bone. But this isn’t surprising. Feathers, muscle, skin, internal organs and other soft structures don’t often preserve as fossils. Most fossils are of hard objects like bones, teeth and shells, which can be more easily turned to rock and survive the ravages of geological time.

With that said, we have good reason to believe T. rex did have some feathers. In China, in the Early Cretaceous, volcanic eruptions buried entire ecosystems similar to how the city of Pompeii was buried by Mount Vesuvius. The dinosaurs were killed and interred quickly, and their soft tissues were locked in place.

Many of these dinosaur skeletons are covered in feathers, including two tyrannosaurs – close cousins of T. rex – called Yutyrannus and Dilong. This means that the ancestors of T. rex had feathers, which means T. rex probably did too.

As an aside, a recent study made headlines by dividing T. rex into three separate species, based on differences in the proportions of the thigh bone. It’s a provocative study, but to me, this variation is minor, and not yet conclusive enough to show whether there was more than one type of T. rex.

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Asked by: Eddie Smith, via email

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Authors

Steve is a professor and palaeontologist at the University of Edinburgh and the author of the book The Rise And Reign Of The Mammals (£20, Picador), a 325-million-year odyssey of mammalian evolution and the people who study mammal fossils.