An herbaceous fossil conifer: Gymnospermous ruderals in the evolution of Mesozoic vegetation

Fast growing conifers have been recognized in disturbed habitats of the tra nsitional Lower Middle Triassic Gres a Voltzia delta from the Buntsandstein in eastern France. These herbaceous conifer fossils reveal that some Mesoz oic seed plants were capable of opportunistic growth and rapid prolific rep roduction long before the origin of flowering plants, Such ruderals indicat e that certain gymnosperms came to characterize river terrace floras by the evolution of reduced size and enhanced reproductive allocation, while othe rs dispersed to dominate more arid expanses of the Mesozoic landscape befor e the rise of flowering plants. The widespread occurrence and quantitative distribution patterns of pollen similar to that of Aethophyllum in the Midd le Triassic suggests that Aethophyllum and related conifers may have played an important role in the evolution of distinctive Mesozoic wetland communi ties. (C) 2000 Elsevier Science B.V. All rights reserved.