STUDY ON THE PALEOECOLOGY OF YIXIAN FORMATION IN BEIPIAO AREA, WESTERN LIAONING PROVINCE, CHINA

The specimens of fossil plants studied in this paper are collected from the second member of Yixian for-matiom at different fossil locastibns in Beipiao area, Western Liaoning. The "feathered" dinosaurs, primitive birds, some reptilian and insect fossils as well as early angiosperm are from the sedimentary strata of laustrine facies(2nd member of Yixian F.). Applying the theory and method of modern phytoecology, the conditon of paleoecology shown by fossil flora are analyzed and discussed. Four fossil communities are set up based on the composition characters of flora and the analysis on the ecology of taxonomic group, i.e. (1) hygrophyte from intracoastal + calcophic vegetation in shallow water:Equisetites longevaginatus + Beipiaoa spinosa Community; (2) lowland-slow-slope:Tjrmia acrodonta + Co-niopteris burejensis Community; (3) intermontane upland:Liaoningocladus boii + Baiera borealis Community; and (4) xerophyte:Pagiophyllum + Gurvanella exquisite Community. By comparing the leaf feature between Yixian flora and modem vegetation in different climatic zones, the Yixian flora indicates a subtropic-warm temperate zone with warm wetness weather. At the same time, the occurrence of deciduous Ginkgoales represents a seasonal variation of the climate. The features of xerophilous Gnetales, Bennettiales with membranous leaves and Conifersles with scaled leaves may indicate a seasonal arid or semi-arid climate condition.