Experts think that T.Rex could have had feathers when they were young in order to stay warm, it would be a fine layer of downy feathers. When T.Rex reached adulthood, their sheer volume would keep the heat efficiently because, in general, bulkier bodies hold heat better. A large Tyrannosaurus certainly a feather cape hinder him when refrigerated ... especially in an era that was believed to be about 6 degrees higher than today. For example, the body of modern elephants generate a large amount of heat, if we add a warm climate, it is hard to imagine that dispense with an insulating layer (either feathers or hair).
Well, if I ever see Steven Spielberg will say that, apart from that the film should be called "Cretaceous Park" by T.Rex would be missing a few feathers.
But ... Why is thought to have feathers?
The fact attributed feathers T.Rex was not formed spontaneously when a paleontologist morning wake up ... no. The idea that the "Tyrant of the saurian" had feathers is suggested by the appearance of the remains of an ancestor, discovered this year in China, and notably had feathers. But not a few, was full of feathers. It was called "Yutyrannus Huali" or Yutyrannus whose name means "beautiful feather Tyrant."
Another example was the Dilong, a dinosaur discovered in 2004 that also keeps a relationship with the T.Rex (are of the same family). This was also covered with feathers.
The Tyrannosaurus, Velociraptor, the Dilong, the Yutyrannus, and many more ... apparently was more common than we think: prehistoric carnivorous dinosaurs had feathers.