COMPARATIVE STUDIES ON THE LATE DEVONIAN FLORAS FROM CHINA AND USA

There is a salient floristic difference between the Chinese and American floras in the Late Devonian. The Chinese Late Devonian floras were represented by the early arborescent lycopsids like Sublepidodendron (Nathorst) Hirmer and Leptophloeum Dawson. In contrast, the coeval American floras were dominated by the early ferns and progymnosperms (such as Archaeopteris and Rhacophyton). Climatic and paleogeographic differentiations from western to eastern areas might have caused this difference. By the Late Devonian, the equatorial current and the trade wind of the ancient Tethys ocean had fewer and fewer influences on the American floras than the Chinese floras, and South China may consist of a part of the Tethyan archipelagic ocean system. Dry continental climate became more and more evident in the Euramerican province than the Cathaysian province in the Carboniferous-Permian due to the continuous growth of a Paleozoic Pangea. By comparing the sedimentology, taphonomy, paleoecology and paleogeography from some Late Devonian localities in China and USA, a better understanding of the Late Devonian paleoclimatic and paleogeographic changes, oceanic anoxic events and biotic crises, especially floral extinction, recovery and succession, will be promising.

*Supported by the NSFC (# 40402001) and a MOA program between Dr. Walter Cressler, West Chester University of Pennsylvania and Dr. Wang Qi, Institute of Botany, the Chinese Academy of Sciences.