The Paleozoic Era is a major division of Earth's history that lasted from about 541 to 252 million years ago. It is known for the emergence of diverse life forms, including the first fish, amphibians, and reptiles. This era is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. During the Paleozoic, the continents were arranged differently than today, and many marine organisms thrived in the oceans. The era ended with the largest mass extinction in Earth's history, known as the Permian-Triassic extinction, which wiped out about 90% of species.