The Law of Superposition is a basically the layers of the earth, stating the youngest layer of rock stay on top and the oldest stay on the bottom as long as they are undisturbed.
Law of Superposition
The Geologic Timescale is a system of chronological dating that relates geological stratigraphy to time. The order of the eras go Cambrian, Paleozoic, Mesozoic, and Cenozoic
In this era there were organisms that began to show up with shells. (541 Million Years ago - 485 Million Years ago)
The Paleozoic era was the era of the first reptiles. This period saw the development of large tropical swamps across North America, Europe and Siberia which are the source of great coal deposits. (323 Million Years ago - 299 Million Years ago)
During the Mesozoic Era, the famous dinosaurs were the dominant species. They were ended by a mass extinction from the meteor that hurdled towards the earth and made many species extinct. (252 Million Years ago - 201 Million Years ago)
Cenozoic was the era the dinosaurs actually went fully extinct along with many other species at the time. (66 Million Years ago - 23 Million Years ago)