The Bayan Nur Geopark holds the biggest and most important late Cretaceous dinosaur fossils in China or even in the East Asia, abundant in fossils, such as ceratopsia, ankylosauria, coelurosauria, furtherover chelonian, crocodilian, saurischian and mammalian, and egg fossils of vertebrates. This paper summarizes the major features of dinosaur fossils and egg fossils, expands the significance of discovery of the dinosaur and egg fossils in studying the biological involvement from extinction of dinosaur to emergence of mammalian during the late Cretaceous.