Size and Weight:
Discovered in 2004 in China, Dilong caused quite a stir: this bipedal theropod was clearly a type of tyrannosaur, yet it lived 130 million years ago, tens of millions of years before bigger (and more famous) tyrannosaurs like Tyrannosaurus Rex and Albertosaurus. Even more astonishingly, there's good evidence that the small, turkey-sized Dilong was covered with primitive, hair-like feathers.
What do paleontologists make of all this? Some experts think Dilong's bird-like attributes--namely its small size, feathers and carnivorous diet--point to a warm-blooded metabolism similar to that of modern birds. If Dilong was indeed warm-blooded, that would be powerful evidence that at least some other dinosaurs had similar metabolisms. And at least one expert has surmised that all juvenile tyrannosaurs (not just Dilong) may have had feathers, which most genera shed on reaching adulthood!