Classification of dinosaur age stages:
1. Triassic: The beginning and end of the Triassic are marked by an extinction event. The rock marks during this period are obvious and clear.
2. Jurassic period: during the Jurassic period, the mainland began to really split, and dinosaurs embarked on the path of independent evolution. The climate of the Jurassic period began to become warm and humid, and the vegetation was luxuriant. Dinosaurs derived a large number of dinosaurs and other creatures with different shapes, such as the huge herbivorous Brachiosaurus and Diplodocus, the raphiosaurus with a long bone plate on its back, the carnivorous ones such as Allotrosaurus, hornnose dinosaurs, Dilophosaurus.
3. Cretaceous: The Cretaceous period is the last period of the Mesozoic era. Compared with the Jurassic period, the dinosaur species are significantly reduced. The relatively prosperous ones are the herbivorous hornosaurs, duckbill dinosaurs, dinosaurs and carnivorous Tyrannosauridae, Arbelidae and Sharodontosauridae on land.