ThePalaeozoic (orPaleozoic)era is the earliest of the three eras of thePhanerozoic. Its name meansearly life. It lasted from about 541 to 252 million years ago (mya) and ended with the greatestextinction event, thePermian–Triassic extinction event. The Palaeozoic was the beginning of plants and animals. In particular, fish dominate the Palaeozoic.
Oxygen content of the atmosphere over the last billion years.[1]
At the start of the longCarboniferous period oxygen was low and carbon dioxide was high. The huge growth of trees and other plants during this time reversed these data. The carbon dioxide level dropped throughout theCarboniferous, and the oxygen level rose continuously until it dropped in the Permian.[2]
Oxygen reached a peak of about 30% about 280 million years ago.[3] That is much higher than today's 21%.
