Time range: 298.9 - 272.3 million years ago
Major Events: Evolution of early reptiles and therapsids.
Time range: 272.3 - 259.8 million years ago
Major Events: Diversification of therapsids, first large herbivorous reptiles.
Time range: 259.8 - 251.9 million years ago
Major Events: Permian-Triassic extinction event.