Study On Juglandaceae Fossils From The Late Miocene Of Lincang,Yunnan Province,China

Yunnan Province is located in the Southwest of China,and the unique geographical and climatic conditions make it has the reputation of the "kingdom of plants".During the uplift process of Qinghai-Tibet Plateau in Cenozoic Yunnan Province experienced several geotectonic movements,and preserved a series of Cenozoic strata.The geotectoic movements also created numerous small basins in Yunnan Province.These basins commonly are known as "Bazi",where not only grow many diverse modern plant types,but also preserved much rich plant fossils.These materials are important for study of the flora's composition and the characteristics of fossil plants in the Cenozoic.In this study,the material was collected from the Bangmai Basin that located in Lincang City,Southwest of Yunnan Province.The Bangmai Flora is much diverse in plant fossils.It provides rich materials to study the vegetation type and the palaeobiogeography of some groups.In this investigation,we studied Juglandaceae macrofossils(including samaras and leaves)based on their morphology.By the detailed comparison,these fossils were assigned into their natural positions of systematics.Especially,the study on reproductive organs of the Juglandaceae,not only as surd the valid of our identification,but also is significant for study of biological evlution.The palaephytogeography was discussed based on the global fossil record of Palaeocarya and Pterocarya.The main conclusions as follows:1.The identification of Juglandaceae plant fossil confirms they belong to 3 genera(Palaeocarya,Pterocarya and Juglans)and 6 species.They are Palaeocarya lincangensis sp.nov,Palaeocarya yunnanensis,Palaeocarya longialata,Pterocarya lincangensis sp.nov.,Pterocarya serrulata and Juglans miocucathayensis.2.Two genera of winded fruits are recognized.They are fossil genus Palaeocarya and the extant genus Pterocarya.3.The global fossil record of Palaeocarya and Pterocarya demonstrated the climate change at the boundary of Eocene and Oligocene(E-O),the famous cooling events in the Cenozoic.It was remarkable for the earth's temperature declined from"Greenhouse" to "Icehouse".