甘肃灵台雷家河新第三纪晚期的大哺乳动物组合及其时代

讨论的大哺乳动物化石出自甘肃灵台雷家河村东南小石沟72074(1)、72074(4)]和文王沟(93002)等地的新第三纪晚期地层。它们包括15种,分属8属、9科、4目,可能代表两个不同时代的组合。第一组合所在的地层层位是72074(4)剖面的L5~L3层和72074(1)剖面的第3层,主要由 Hipparion pater、Acerorhinus sp．、Nyctereutes．、 Hyaeninae gen．et sp．indet．和Gazella niheensis等类型组成,其性质与山西榆社高庄组南庄沟段和醋柳沟段产出的大哺乳动物的接近,时代可能为中上新世。第二组合所在的地层层位是72074(1)剖面的第2层,以Anancus sinensis 和Cervidae gen．et sp．indet．为代表,其性质与榆社麻则沟组动物群的相近,时代为晚上新世。

THE LATE NEOGENE MACROMAMMALIAN ASSEMBLAGES FROM LINGTAI, GANSU PROVINCE, CHINA

A series of Late Neogene deposits are well developed in the area near the Leijiahe Village, Lingtai County, Gansu Province.Since 1972s, a great amount of mammalian fossils have been collected at 72074(1), 72074 (4), 93001 and 93002 sections of the area. Among them, the micromammalian remains were identified by Zheng and Zhang (2000 and 2001) and according to them, 4 biostratigraphic zones are recognized at the 72074(4) section. The ages of the I - IV zones are from Late Miocene to Late Pliocene.The macromammalian remains, mostly represented by teeth and fragmentary limbs, are obtained from the L3 - L5 and L8 of the section 72074(4), the 2 - 3 layers of the section 72074(1) and the CL4 - CL5 of the section 93002. However, the amount of the specimens are much less than those of the micromammals, even in the same section and in the same layer. Up to now, 15 species, assigned to 8 genera and 9 families of Camivora, Proboscidea, Perissodactyla and Artiodactyla have been identified. They are Nyctereutes sp. , Caninae gen. et sp. indet. , Hyeninae gen. et sp. indet. , Martes sp. , Felis sp. , Hipparion pater, H . houfenense , Hipparion sp., Acerorhinus sp., Anancus sinensis , Proboscidea gen. et sp. indet. , Cervidae gen. et sp. indet. , Gazella niheensis , Gazella sp. and Oioceros sp. etc. Their distribution in the sections 72074(1) , 72074(4) and 93002 is given in the table 1 .The macromammals are dominated by the herbivores, especially Hipparion and Gazella . They may contain more than two assemblages belonging to the different ages. The first assemblage,yielding from the L3 - L5 of 72074(4) section and the 3rd of 72074(1) section, consists of Hyaenidae gen. et sp. indet., Hipparion pater. Acerorhinus sp. and Gazella niheensis . Besides, it contains Nyctereutes sp. , Felis sp. , Hipparion houfenense , Proboscidea gen. et sp. indet. and Cervidae gen. et sp. indet. , which are known from the 72074 (4) section, and Caninae gen. et sp. indet. and Martes sp. from 72074 (1) . It is characterized by the last occurrence of Acerorhinus , the first appearance of Nyctereutes and Gazella nihensis , the absence of Homotherium , Lynx shansius , Anancus sinensis , Mammuthus sp. , Antilospira licenti, and Gazella sinensis etc., which are first appeared in the Late Pliocene in Northern China, and the absence of Indarctos, Ictitherium , Adcrocuta , Hipparion dermatorhinus , Chilotherium , Sinotherium , Chleuastochoerus, Cervavitus novarossiae, Gazella gaudryi and G. dorcadoides etc. , which are the last occurrence in the Late Miocene of Northern China. Therefore, it is comparable with the assemblage from Nanzhuanggou Member and Culiugou Member of Gaozhuang Formation of Yushe basin, Shanxi Province. Its age may be Middle Pliocene.The second assemblage, yielding from the 2 layer of 72074(1) , consists of Anancus sinensis and Cervidae gen. et sp. indet. Anancus sinensis is one of the typical forms in the late Pliocene fauna of Northern China. Its first occurrence is in the Mazegou Formation of the Yushe basin, Shanxi Province. The age of the assemblage is Late Pliocene and may be comparable with the Mazegou one.The materials yielding from the L8 of 72074(4) section and CL 5 - CL4 of 93002 section are too rare to form assemblages. Zheng and Zhang (2000, 2001) considered the layers are of late Miocene and the Early Pliocene respectively according to the micromammals.