The end-Triassic mass extinction, 201 million years ago, is linked to volcanism that resulted from the break-up of Pangea and which pumped out vast amounts of CO2 into the atmosphere, causing extreme global warming of 5 to 10 degrees Celsius. As a result, tree-dominated vegetation collapsed and the highly disturbed landscapes were colonized by ferns that formed savannahs across large swaths of what is now Northwest Europe.