The name of the 26-foot (8-meter) hadrosaur Maiasaura, or “good mother lizard,” was based on fossil finds in Montana. The nesting colony spanned 2.5 acres and included 40 nests, each containing up to 25 grapefruit-sized eggs. This herbivorous dinosaur showed an advanced social and breeding behavior, including returning to the same nesting sites every breeding season, refurbishing existing nests, placing nests one dinosaur length apart (about 25 to 30 feet [7.6 to 9.1 meters]) so there was room for movement back and forth, incubating eggs using a warm compost layer, and feeding the nest-bound young with vegetation until they were ready to leave.