The Tiny T-Rex ( Raptorex) lived about 60 million years before T-Rex. It seems as though size was about the only evolutionary change between the two. It’s amazing to think that 60 million years of evolution wouldn't change it's bone structure at all. I was reading on National Geographic, and apparently scientist still believe that earlier ancestors to the two dinosaurs had longer arms. It's hard to image a T-Rex (large or small) with longer arms. Seems like it would throw off it's balance or something.