Real Maiasaura were large, 9-metre long hadrosaurs that lived in what is now Montana 75 million years ago, in the Late Cretaceous period. They lived in large herds to discourage attacks from predators such as the tyrannosaur Daspletosaurus. Maiasaura eggs, nests, and hatchlings have been discovered, showing evidence that these common dinosaurs took care of and fed their young. The name Maiasaura means "caring mother lizard".