Quantitative analyses of the early angiosperm radiation

Abstract

Although the pattern of the early angiosperm radiation has been substantially clarified by palaeobotanical and stratigraphic investigations over the last 30 years1–3, knowledge of associated vegetational and floristic change remains limited. Quantitative analyses of Cretaceous fossil floras indicate that by ∼90 million years before present (BP) angiosperms had achieved widespread floristic dominance, at least in the Northern Hemisphere. Although some non-angiosperm plant groups show no pronounced shifts in diversity in association with the angiosperm radiation, others show marked declines that contribute to profound alterations in the composition of terrestrial plant communities. Comparative trends in systematic diversity suggest competitive displacement of cycadophytes and pteridophytes by angiosperms, but current evidence is not sufficient to exclude the probability of a more complex basis for mid-Cretaceous floristic change.