The Paleozoic Era is a significant period in Earth's history that lasted from about 541 to 252 million years ago. It is known for the emergence of many 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 the climate varied widely. The era ended with the largest mass extinction in Earth's history, known as the Permian-Triassic extinction, which wiped out approximately 90% of marine species and 70% of terrestrial vertebrates.