Feather furore: T.rex may not have been fluffy after all, skin study suggests | Susannah Lydon

Recent speculation that giant dinosaur predators were covered in downy feathers has been challenged by a new study of tyrannosaurid skin

The evolution of feathers, and how this relates to bird evolution, is something that even people outside the world of palaeontology can get very agitated about. Just look at the recent debate around the lack of feathers on the GM theropods in Jurassic World. By the 1990s, it was pretty much accepted by everyone (well, everyone apart from one or two very vocal opponents) that birds were the descendants of theropod dinosaurs. 'Non-avian dinosaurs' is now a standard phrase in the literature: a constant reminder that birds are just the final twigs of a much larger branch of the tree of life. Our cut-off point between the concepts of 'dinosaur' and 'bird' is due to the fact that dinosaurs were extinct before people starting classifying living things, rather than anything to do with their evolutionary relationship.

Since the well-publicised discoveries of exquisitely-preserved feathered dinosaurs from China, the debate has shifted from "did dinosaurs have feathers?" to "which dinosaurs had feathers, what sort of feathers did they have, and where did they have them?". We can even look at changes in feathers through the lifetime of a dinosaur, from juveniles to older individuals. The species that have been described with true feathers are all theropods: the bipedal, carnivorous dinosaur group. There is no evidence for feathered sauropods (the enormous, long-necked, four-legged herbivores), but there is some evidence for feather-like filaments in other dinosaur groups, which some researchers have interpreted as evidence that dinosaurs as an entire group may have possessed feathers as an ancestral condition. Against this is the fact that most dinosaur integument impressions show scaly, 'reptilian' skin.