Flowers of Turonian Magnoliidae and their implications

Abstract

Recently discovered fossil flowers of Magnoliidae from Atlantic Coastal Plain deposits of Turonian age are considered in the context of the overall fossil record of magnoliid reproductive remains. The assemblage of fossils from these Turonian localities is diverse and affects our understanding of the history of reproductive structures in the Magnoliidae (and in the angiosperms in general). Within Piperales (sensu Cronquist 1981), they include the earliest stamens similar to those of modern Chloranthus. Turonian fossil Magnoliales document early diversity of complicated flowers with numerous spirally arranged organs and laminar stamens and also reveal diversity in Magnoliales with cupulate floral receptacles. In Laurales, there are two taxa of fossil flowers of Lauraceae, and a fossil flower sharing some, but not all, characters with Calycanthaceae. In the context of the overall Cretaceous record of angiosperms, these fossils have important implications with respect to the sequence of appearance of disparate types of floral morphology in Magnoliidae. They also reveal diversity in character complexes now associated with several different modes of insect pollination and suggest that during the Turonian, passive (e.g., wind) dispersal of seeds was important in magnoliid taxa.