"Mother Maiasaur" is a character who appears in The Land Before Time II: The Great Valley Adventure. She is, as her name implies, a Maiasaura.
She scolds the Prehistoric Pals for rolling rocks down a hill, her reasoning being that they potentially could have damaged her nest. She is unaware that said rock rolling had inadvertedly thwarted an attempt by Ozzy to raid her nest.
She was labeled as "Mother Maiasaur" in the credits and was voiced by Tress MacNeille.