Amanda Kelley

World’s only fossils of T. rex skin suggest it was covered in scales—not feathers

Was Tyrannosaurus rex—the giant king of the tyrannosaurs—actually sporting bright plumage? Mounting fossil evidence of feathers and protofeathers on several T. rex cousins has intensified the debate. But without direct proof that T. rex had feathers, some scientists decided to hunt for clues in the next-best place: fossilized skin. They examined the world’s only known fossils of T. rex skin—from the neck, pelvis, and tail of a long-dead dino named Wyrex, stored since 2006 at the Houston Museum of Natural Science in Texas (above). They found no sign of feathers; just smooth, scaly skin. They also analyzed skin impressions from large tyrannosaurs that lived around the same time, such as Albertosaurus and Gorgosaurus. Like Wyrex, those dinosaurs were covered in scales, they report today in Biology Letters. So if these large tyrannosaurs had any feathers at all, says the team, their fluff would have been limited to their backs—the only body part for which they were lacking fossil impressions.Because their earlier cousins did have feathers, it’s likely that the large tyrannosaurs lost them somewhere along the way, the team suggests. It’s possible that the giants didn’t need feathery thermal insulation, as their bodies were better able to retain heat.