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在海南岛长昌盆地始新世长昌组中发现了樟科植物一新种长昌油丹Alseodaphnechang changensissp.nov.的完整叶片化石标本,这是迄今发现的时代最早、纬度最低的油丹属化石,为进一步研究该属植物的起源和演化以及海南岛始新世古气候提供了新的化石资料.根据叶的形态和表皮特征,当前标本与现生油丹A.hainanensis Merrill最为相似.现生油丹主要分布在海南岛热带低地雨林、热带山地雨林和亚热带山地常绿阔叶林,在广东珠海万山群岛和越南北部也有少量分布.这些分布地的年均温为20～22.6℃,气温年较差12～12.6℃,年降雨量1784～2500mm.根据最近亲缘种原理,推测海南岛长昌盆地始新世古气候可能接近于现生油丹分布地的气候.
A complete leaf fossil specimen of the new Lauracetus species Alseodaphnechang changensissp.nov. Was found in the Changchang Formation of the Eocene in the Changchang Basin, Hainan Island. This is the earliest and lowest latitudinal discovery of the genus Dansen The fossils provide new fossil data for further studying the origin and evolution of the genus and the Eocene Paleoclimate in Hainan Island.According to the morphological and epidermal characteristics of the leaves, the present specimen is most similar to A.hainanensis Merrill Oil Dan mainly distributed in the tropical lowland rain forest of Hainan Island, tropical mountain rainforest and subtropical mountain evergreen broad-leaved forest in Guangdong Zhuhai Wanshan Islands and northern Vietnam also have a small amount of distribution of these annual average temperature of 20 ~ 22.6 ℃, temperature The annual difference is 12 ~ 12.6 ℃, annual rainfall is 1784 ~ 2500mm.According to the recent kinship theory, it is speculated that the Eocene paleoclimate of Changchang basin in Hainan Island may be close to the climatic distribution of present oil Dan.