Acer Fossils And Quantitative Reconstruction Of Paleoclimate In The Late Miocene Of Lincang,Yunnan Province,China

Yunnan Province is a favorable area for study of plant diversity,floristic evolution and migration routes of angiosperms.It is also a best place for study of fossil plants for palaeobotanists.Lincang city is located in the southwest region of Yunnan Province.Landforms are mostly intermontane basins,The strata are well developed and exposed.containing aboundant fossils of angiosperms,which provides good material for study of Cenozoic angiosperms.In this study,We choosed 25 Acer fossils to investigate from the upper Miocene Bangmai Formation of Lincang,Yunnan Province,They are assigned into four species including one new species-Acer lincangense sp.nov.and one conformis-Acer cf jingdongense.The occurrence of the genus Acer in Bangmai Formation provides the evidence that this flora was mixed with North Temperate elements and paleotropical elements.Finally,On the basis of statistical analyzis of the number of fossil and extant species,we find the evolutionary history of the diversity of Acer can be divided into three maximum phases,i.e.,Eocene,Miocene and post-Holocene.The number of species diversity through geological time is spirally increased.Also could be seen the environment of Acer is north temperate zone or subtropical mountains.Also,we choosed 357 specimens of angiosperm leaf fossils from the upper Miocene Bangmai Formation to conduct a paleoclimatic analysis.These leaves were devided into 39 morphotypes generally to do LMA analysis.We obtained MAT was 18.9?.Then,The 30 morphotypes among 39 morphotypes with qualified morphology were selected for CLAMP analysis(online or offline).We obtained 11 climatic parameters of the late Miocene of Lincang,such as the annual average temperature(MAT)was 18.19±1.25?,rainfall(GSP)was 1441.5±217.7mm,etc.At last,we compared them with those of the present.The result shows that the late Miocene is a bit more warm and humid than today in Lincang,and the climate type also belongs to subtropical climate.In line with growing environment of Acer.