sentences:  Most plant groups were relatively unscathed by the Permo-Triassic extinction event, although the structures of communities changed.This may have set the scene for the appearance of the flowering plants in the Triassic (~), and their later diversification in the Cretaceous and Paleogene.The latest major group of plants to evolve were the grasses, which became important in the mid-Paleogene, from around .