For 140 million years, dinosaurs ruled the world! What is now Montana was once their great kingdom. Montana's state fossil is the Maiasaur, or "Good Mother." It is called this because of the way the species cared for its young. The discovery of its fossilized nests and eggs in Montana caused scientists to rethink old theories about dinosaurs. Some of the biggest dinosaur discoveries are made right here in Montana. The fifteen stops along the Montana Dinosaur Trail allow you to discover these paleontological breakthroughs for yourself.