Name Means: "Good Mother Lizard"
Time: Late Cretaceous (80-65 million years ago)
Location: Montana
This duck-billed plant-eater got its name when fossils were found alongside eggs, nests and young. Paleontologists think a female laid about 25 grapefruit-sized eggs in a leaf-lined ground nest, and then cared for the young until they had at least doubled in size (Maiasaura was about a foot long at birth). Adults reached 30 feet long, 8 feet tall and weighed 8,000 pounds. They bred in large colonies and returned to the same nesting sites annually.