T T he first known fossilized skin impressions for Tyrannosaurus rex suggest that this gigantic carnivore, unlike many other dinosaurs, had little to no feathers.
The fossils, reported in the journal Biology Letters, show that T. rex was instead covered with a tough and scaly hide. Fossilized skin impressions for other tyrannosaurs — including Albertosaurus, Gorgosaurus, and Daspletosaurus — reveal that all such dinosaurs lacked feathers, too.
Co-author W. Scott Persons and his colleagues were thrilled when they first saw the T. rex remains, which preserve numerous patches of skin impressions from the dinosaur’s neck, pelvis, and tail.
“Mostly I couldn’t wait to touch it!” Persons said, referring to one such well-preserved fossil. “It is every kid’s dream to pet a T. rex, and — if we are honest — it is also every dinosaur paleontologist’s.”
“The skin is bumpy,” he continued. “None of the scales are as big as what you see on the back of a crocodile, but they are similar to the scales along a croc’s flank. I suppose tyrannosaur hide would make for a nice set of luggage.”
The T. rex remains were unearthed near the town of Baker, Montana, and date to the Late Cretaceous (100.5–66 million years ago). Lead author Phil Bell of the University of New England, Persons, and the rest of the international team examined the fossils in detail. The resulting information, combined with observations of the other dinosaur remains, allowed the researchers to assemble a new dataset concerning both tyrannosaur skin and overall body size.
The scientists note that the wolf and lion-sized ancestors of tyrannosaurs were among the first carnivorous dinosaurs to be discovered with feathered, rather than scaled, skin. Over the course of evolution, many in the lineage must have therefore lost their feathers.
Persons said that the feather coats of the tyrannosaur ancestors probably served as insulation to hold in body heat. As T. rex and certain other tyrannosaurs grew ever larger over time, their need for feathers probably diminished.