The occurrence of Burretiodendron from the Oligocene of South China and its geographic analysis

Abstract The fossil records of Burretiodendron Rehder are reviewed based on diagnostic winged fruits from the Oligocene Ningming Formation, Guangxi, South China. Today, this genus is endemic to Southeast Asia with six extant species that are well distributed in limestone mountain forests under a monsoonal climate. The fossil records of this genus were represented only in Yunnan of southwestern China. The fossil fruits are assigned to a new species, Burretiodendron guangxiensis J.L. Dong et B.N. Sun sp. nov., are smaller than those of living species. Burretiodendron is a good indicator of paleoclimate and karstification due to its restricted distribution which is determined by specific temperature, precipitation and the topographic condition. We investigated the climate requirements of Burretiodendron . It is possible to accurately infer that the Ningming paleoflora represented a warm and humid climate with seasonal precipitation during the Oligocene. Edaphic preferences of the nearest living relative identified for the fossil species may point to the existence of a karstic system in the Ningming Region during the Oligocene.