Dinosaurs probably communicated both vocally and visually. Large meat eaters like Tyrannosaurus rex, with its loud roar, or a Triceratops shaking his head, would hae made its intentions very clear. The chambered head crests on some dinosaurs such as Corythosaurus and Parasaurolophus might have been used to amplify grunts or bel- lows. Mating and courtship behavior and territory fights probably involved both vocal and visual communication. Scientists believe that the sounds created by dinosaurs like Parasaurolophus were so individual that each had a slightly different tone. They also believe that these dinosaurs had different calls, ranging from low rumbles to high-pitched notes, which they used for different situations.