Abstract:

Yunnan Province is a favorable place for investigation of plants diversity, floristic evolution and migration routes of
angiosperms. In this study, eight leaf impressions and seventeen winged fruits ofAcer from the upper Miocene Bangmai Formation of
Lincang, Yunnan Province were investigated. 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 the Bangmai Formation provides the evidence that the
Lincang flora was mixed with elements of the north temperate and paleotropical zones. And this character of Neogene floristic diversity
formed the basis of modern plant diversity in Yunnan Province. Furthermore, on the basis of statistical analysis of the number of fossil
species at different geological periods and extant species at present, the evolutionary history of the diversity of Acer can be divided into
three optimum phases, i.e., the Eocene, the Miocene and the post-Holocene. The diversity of Acer at species level is spirally increased
through the three evolutionary cycles.

Key words: Lincang, Bangmai Formation, Late Miocene, Acer, biodiversity