What are the different periods in the Earth's history?

After the 'Archeozoic' period of the Precambian era, which lasted till about 550 million years ago, came the Paleozoic era.  This era is subdivided into Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian periods. In the Cambrian period, different types of organisms lived in the sea. The first land plants appeared in the Ordovician period. This fact can be proved with the help of fossils. The Mesozoic or the 'medieval age of the Earth', which is classified into the Triassic, Jurassic, and Cretaceous periods, began around 250 million years ago. The first mammals, as well as the dinosaurs, first appeared in the Triassic period. At the end of the Cretaceous period, the dinosaurs became extinct. Man evolved in the late Cenozoic period, which started about 65 million years ago.