Which dinosaur had a mouth so big that a cow could have fit inside? Give up? It was Tyrannosaurus rex. The dinosaur’s 50 sharp teeth, however, would have made its mouth an uncomfortable place for any creature. Let’s try another one: which dinosaur could run 45 mph [72.4 kmh]? Struthiomimus, of course—the world’s fastest dinosaur. These details and other fascinating facts will keep young dinosaur enthusiasts turning the pages for more. Interactive features such as pop-up word definitions, multi-touch zoom, and interactive study cards deliver an experience beyond the printed book.