Muttaburrasaurus was one of the largest creatures in the southern hemisphere at its time. At 8 metres long and 3 tonnes it dwarfed all other herbivores, and carnivores in its environment. Despite its overwhelming size it was not particularly fast, but it didn't need to be. Sheer size was its defense. Only the oldest, or the sickest were at risk from predatory Allosaurs. Muttaburrasaurus certainly lived in large groups for extra protection just in case. Muttaburrasaurus had a large bony growth on its nose, from the eyes to the tip of the jaw. It is likely, given that it is a hadrosaur that this was some kind of resonating chamber that was used for communication. This also supports the idea that they lived in groups.