Ever since tyrannosauroid fossils (namely, Dilong and Yutyrannus) started turning up with evidence of feathers, the idea that the Big T and its close relatives were at least partially feathered themselves was awfully intriguing. I mean, basal coelurosaurs had feathers, early tyrannosauroids had feathers—it stood to reason. But a new study examining fossilized tyrannosaur skin impressions concludes that Tyrannosaurus and its close relatives Albertosaurus, Daspletosaurus, Gorgosaurus and Tarbosaurus had scaly skin rather than feathers. Size may be one reason why: large mammals are less hairy for heat-loss reasons (the exceptions being arctic dwellers like mammoths).
I admit to some disappointment: I was more invested in the idea of a feathered T. rex than I ought to have been.