泥河湾哺乳动物群与中国第四系下限

NIHEWAN FAUNA AND Q/N BOUNDARY IN CHINA

对泥河湾动物群（狭义）与欧洲维拉方经典动物群中属级相同的２０种哺乳动物进行形态和进化水平上的对比发现，其中有１１种（包括亚种）和晚维拉方期的 Ｏｌｉｖｏｌａ动物群的成员最接近，有４种可与中维拉方晚期的Ｓｅｎｅｚｅ动物群的成员比较，其中有２种因为仅发现于Ｓｅｎｅｚｅ，不足以说明它们一定只和泥河湾者接近。另外两种（Ｌｙｎｘ ｓｈａｎｓｉｕｓ和Ｐｓｅｕｄｏｄａｍａｅｌｅｇａｎｓ）确实和Ｓｅｎｅｚｅ者更接近而不同于Ｏｌｉｖｏｌａａ者。有两种动物（Ｂｏｒｓｏｄｉａ ｃｈｉｎｅｎｓｉｓ和Ｍｅｌｅｓ ｃｈｉａｉ）间接地表明泥河湾动物群可能和 Ｏｌｉｖｏｌａ更接近。还有 ３种时代意义不大。总之，对比表明泥河湾动物群（狭义）与欧洲晚维拉方早期的Ｏｌｉｖｏｌａ动物群最为接近，其年代应为１８Ｍａ左右，接近于海相Ｖｒｉｃａ剖面更新世／上新世界线（１．７９６Ｍａ）。

A comparison between the Nihewan mammalian fauna (s. s.) and those of the Villafranchian age in Europe was carried out based on 20 commonly shared mammals at generic and/ or specific level. Eleven of them (Vulpes sp., Canis chihliensis, C. c. palmidens, C c. minor, Ursus of. U. etruscus, Pachycrocuta licenti, Chasmaporthetes of. C ossifragus, Megantereon nihowanensis, Homtherium cf. H. crenatidens, Sus sp. Eucladoceros boulei) show close morphologic similarity with corresponding forms of the Olivola fauna. Four forms (Nyctereules sinensis, Lynx shansius, Pseudodama elegans, Megalovis piveteaui) are to be compared with their counterparts of Seneze fauna based on different grounds. Nyctereutes megamastoides became extinct after Seneze, while Megalovis was found in Europe only in Seneze. Lynx shansius and Pseudodama elegans are truly closer to their counterparts in the Seneze fauna than in Olivola. The Olivola lynx, Lynx issiodorensis, minima, became reduced in general body size, while that of the Nihewan fauna did not The Olivola Pseudodama nestii is certainly more advanced in character than its counterpart in Nihewan, Pseudodama elegans. Two forms (Meles chiai and Borsodia chinensis) are, at least not opposite to the possibility to compare the Nihewan with Olivola. Although Meles thorali from Saint Vallier is the only record in the European Villafranchian, it is ceylonly more primitive in general evolutionary level than M chiai of the Nihewan fauna. On the other hand, Borsodia newtoni, which is generally considered the form most closely related to the Chinese one, ranges from Seneze to Forest beds. Three forms are not very useful in phylogenetic analysis: Sivapanthera pleistocaenus (probably a new species), Equus sanmeniensis, and E. teilhardi. If the above comparison proves tenable, the base of the Nihewan fauna will be coincident with the late Villafranchian, and consequently with the Q/N boundary defined at the Vrica marine section and the top of C2n (= Olduvai) in the astronologically calibrated GPTS, which is dated l.796Ma.