Before revision: Greenhouse and icehouse periods have played key roles in the evolution of life on Earth by directly and indirectly forcing biotic adaptation and turnover at various spatial scales across time.970x970px||center Greenhouse Earth alt=An illustration of ice age Earth at its glacial maximum.|An illustration of ice age Earth at its glacial maximum.
After revision: the lastGreenhouse and icehouse periods have played key roles in the evolution of life on Earth by directly and indirectly forcing biotic adaptation and turnover at various spatial scales across time.970x970px||center Greenhouse Earth alt=An illustration of ice age Earth at its glacial maximum.|An illustration of ice age Earth at its glacial maximum.