FOSSIL EVIDENCE FOR THE EVOLUTION OF BIOTIC POLLINATION

The Cretaceous-Paleogene history of plants and insects reveals a discernible pattern in the evolution of floral character complexes and insects. Earliest Cretaceous flowers were small apetalous magnoliids with few parts. They co-occurred with a greater variety of anthophilous insects than has previously been supposed, and the idea that Coleoptera were the principal early insect pollinators is in need of review. By the mid-Cretaceous rosid flowers are known with well-developed corollas and the Rosidae are diverse by the late Cretaceous. The more derived asterid floral types are not firmly established until the Tertiary. Nectaries are present in many of the late Cretaceous rosids and may signal the beginning of the most significant evolutionary interaction between Hymenoptera and angiosperms. Advanced floral types in Maastrichtian and early Tertiary deposits are consistent with the appearance of meliponine Apideae (Stingless honeybees) in the late Cretaceous.