亚洲早古近纪哺乳动物生物年代学与生物地理学的新认识(英文)

AN UPDATED MAMMALIAN BIOCHRONOLOGY AND BIOGEOGRAPHY FOR THE EARLY PALEOGENE OF ASIA

近期的研究极大地丰富了亚洲古新世和早始新世哺乳动物群信息,因此有必要对现存亚洲生物年代学和生物地理学框架做出调整。在定量和定性分析的基础上,将生物年代界线与主要的动物群更替事件对应起来,改进了古新世和早始新世亚洲陆相哺乳动物分期年代对比及生物地理学的认识。以往知之甚少的上湖期以原始啮形类和钝脚类为主,其后的浓山期则呈现出亚洲哺乳动物的地方性分异。随着新的基干啮形类以及真正的啮型类的出现,啮形类开始辐射。上湖期-浓山期的界线与北美Torrejonian-Tiffanian界线相当,并且动物群更替很可能是由全球变冷阶段的开始引发的。格沙头期哺乳动物进一步分化,亚洲土著类群急剧减少,以多瘤齿兽类、夜鼩类(nyctitheriids)、克莫土兽类(cimolestids)和食果猴为代表的北美迁入物种开始出现。而在北美,亚洲哺乳动物(包括北柱兽类和原恐角兽类)的第一次入侵发生于Tiffanian-5a期初期,第二次入侵发生于Clarkforkian初期,包含了啮齿类、裂齿类及冠齿兽类。因此格沙头期的开始可与北美Tiffanian-5a的开始相对比。伯姆巴期的开始以偶蹄类、奇蹄类和真灵长类的首次出现为标志,与古新世-始新世界线相当。这些类群在亚洲的出现与它们在北美和欧洲出现于始新世之初的情况类似。与格沙头期初期的动物群扩散不同,伯姆巴期的动物群扩散似乎持续了更长时间,并且也有可能直接发生在亚洲和欧洲之间。

Recent research has greatly increased the information available on Asian Paleocene and early Eocene mammal faunas,creating the need to update the existing Asian biochronological and biogeographical framework.Based on a quantitative and qualitative analysis,biochronological boundaries are refined to correspond to major faunal turnovers,and an improved age correlation and biogeography of the Paleocene and early Eocene Asian Land Mammal Ages（ALMAs） is proposed.The poorly known Shang-huan ALMA is characterised as an assemblage dominated by primitive gliriforms and pantodonts.The following Nongshanian ALMA shows an endemic diversification of Asian mammals.Gliriforms radiated,with the appearance of new basal gliriforms and the first appearance of true Glires.The Shanghuan/Nongshanian boundary has been correlated to the Torrejonian/Tiffanian boundary in North America,and it is suggested here that the faunal turnover was possibly triggered by the start of a period of global cooling.The following Gashatan ALMA witnesses a further diversification and an abrupt reduction of the endemism of Asian mammals.Multituberculates,nyctitheriids,cimolestids and carpolestids appeared in the Gashatan faunas and represent North American immigrants.Conversely,a first wave of Asian mammals consisting of arctostylopids and prodinoceratids invaded North America at the start of Tiffanian-5a,and a second wave consisting of rodents,tillodonts and coryphodontids arrived in North America at the beginning of the Clarkforkian.The start of the Gashatan is therefore correlated with the start of North American Tiffanian-5a.The start of the Bumbanian ALMA is marked by the first appearance of artiodactyls,perissodactyls and true primates,similar to their appearance in North America and Europe at the start of the Eocene,and is correlated to the Paleocene-Eocene boundary.Contrasting with dispersal at the start of the Gashatan,dispersal during the Bumbanian seems to have been possible during a more extended period,and was also possible directly between Asia and Europe.