Carboniferous Rainforest Collapse

Approximately 305 million years ago, the vast tropical coal swamp forests that had covered equatorial Euramerica for tens of millions of years fragmented and collapsed. Intensifying glacial cycles drove a shift from persistently humid to seasonally arid conditions, and atmospheric CO₂ dropped to levels comparable to modern ice ages — partly because the forests themselves had sequestered enormous quantities of carbon as peat and coal. The collapse extinguished the dominant arborescent lycopsid trees and fragmented habitats into isolated patches. This drove the diversification of early amniotes, whose water-independent eggs gave them a decisive advantage over amphibians in the drier landscape.