1. Paleozoic Era (541 million years ago - 252 million years ago): This era is known as the "Age of Ancient Life" and is characterized by the emergence and diversification of complex life forms. It is further divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. During this era, life evolved from simple marine organisms to the first vertebrates and land plants.

2. Mesozoic Era (252 million years ago - 66 million years ago): Known as the "Age of Reptiles," the Mesozoic Era saw the dominance of dinosaurs and other reptiles. This era is divided into three periods: Triassic, Jurassic, and Cretaceous. The rise of mammals and the extinction of dinosaurs at the end of the Cretaceous period are significant events that occurred during this era.