|This picture is from the slideshow that accompanied this National Geographic article.|
According to both the National Geographic article and the American Natural History article, the Dilong paradoxis was covered with protofeathers, which were presumably to keep the dinosaur warm. Unlike the Dilong paradoxis, the Tyrannasaurus rex, because of its large body mass, would have more difficulty expelling heat than generating it, so it is reasonable to suppose that the T-rex did not have feathers. However, according to the American Natural History article, it is plausible that the young Tyrannasaurus rexes might have had protofeathers for warmth which they molted as they matured.
There is a great NPR piece on the Dilong paradoxis. Also, if you were like me and you grew up reading about dinosaurs and watching Walking with Dinosaurs over and over again there is apparently a paleontological blogging community (I love the internet!) that is out there. As I was doing research, I stumbled across the blog of a Marshall student named Nick Gardner, called "Why I Hate Theropods." I immediately decided to find out what a theropod was (see the top of this blogpost). He wrote an blogpost on the subject, which illuminates some of the scientific debate on the subject. Overall, I am sorry to say, that Nick's terminology is too technical for my classicist mind (although I once had some aspirations of becoming a paleontologist, those went by the wayside when I realized that I neither have the patience nor the complexion for the incredible and painstaking art of uncovering dinosaur bones), but his blog is quite fascinating nonetheless and even disregarding the jargon of biological classification his overall points are generally clear.
- Tyrannasaurus Rex more or less translates as "the tyrant king" which is pretty amusing considering that tyrannos, tyrant, was set in oppositition to basileus (and in Latin rex) because tyrants were considered to be those who did not inherit the thrown, whereas a king came to the position by birth.