CarboniferousPermian

The Carboniferous-Permian interval is an informal label for the span of Earth history that covers the late Carboniferous and early Permian periods of the Paleozoic Era. In conventional geologic time, the Carboniferous lasted from about 359 to 299 million years ago and is divided in North America into the Mississippian and Pennsylvanian subperiods; the Permian followed from about 299 to 252 million years ago and is divided into the Cisuralian, Guadalupian, and Lopingian epochs. The boundary between the two periods marks a major ecological and climatic transition that set the stage for Permian terrestrial biotas and the subsequent end-Permian crisis.

Ecologically, the Carboniferous is noted for expansive coal-forming swamp forests, high atmospheric oxygen, and the evolution and diversification of early amniotes and giant arthropods. The Pennsylvanian witnessed widespread cyclothems, fluctuating sea levels, and ongoing forest development, especially in Euramerica; Gondwanan records preserve evidence of continental glaciation that influenced global climate and sea level.

In the Permian, land ecosystems became increasingly dominated by seed plants and by amniotes, including more advanced synapsids and reptiles. The supercontinent Pangaea created extreme interior climates, with arid to semi-arid conditions in many regions but coastal belts remaining humid. Marine faunas diversified and later declined as conditions changed.

The interval ends at the Permian-Triassic boundary around 252 million years ago, marked by the greatest known mass extinction, which profoundly altered global biodiversity and opened ecological space for Mesozoic life. The Carboniferous-Permian interval thus represents a pivotal transition in Earth's climate, geography, and biotic evolution.