Maiasaura peeblesorum ("Peebles' good mother lizard") is a huge duck-billed dinosaur species that lived in Montana in the Upper Cretaceous (Companion), 74 million years past.
Maiasaura was exposed by dinosaur paleontologist Jack Horner (paleontologic advisor for the Jurassic Park movies). He named the dinosaur after a series of nests with remains of eggshells and hatchlings. This was the first show of giant dinosaurs raising and feeding their young. Over 200 specimens, in all age ranges, have been establishing.
Maiasaura was quite a odd looking animal: it was large, about 7 meters long, and it had the typical hadrosaurid flat beak and a thick nose. It had a small, spiky crest in front of its eyes. The shape of the head was reminiscent of a horse's. This dinosaur was herbivorous. It walked both on two or four legs and it had no defense against predators, excepting, perhaps, its heavy muscular tail and its herd behavior.
It lived in herds and it raised its young in nesting colonies. The nests, containing 30 to 40 eggs, were made of earth, and were protected by the parents (parental care). The eggs had about the size of ostrich eggs, so the hatchlings had to produce fast.
Maiasaura lived alongside with the ceratopsid Centrosaurus, the tank-like Euoplocephalus, and an previous relative of Tyrannosaurus rex, Daspletosaurus torosus.