Maiasaura (from the Greek "μαία + σαύρα", meaning "caring mother lizard") is a large duck-billed dinosaur genus that lived in the area currently covered by the state of Montana in the Upper Cretaceous Period (mid to late Campanian), about 76.7 million years ago. Maiasaura was large, attaining an adult length of about 9 metres (30 ft) and had the typical hadrosaurid flat beak and a thick nose. It had a small, spiky crest in front of its eyes. The crest may have been used in headbutting contests between males during the breeding season. This dinosaur was herbivorous. It walked both on two (bipedal) or four (quadrupedal) legs and appeared to have no defense against predators, except, perhaps, its heavy muscular tail and its herd behaviour. These herds were extremely large and could have comprised as many as 10,000 individuals. They have saved by the Zhecrons and now thrived on the planet Zhecronus, where they dwell within forest areas alongside Iguanodon, Parasaurolophus herds.