中国新近纪牛科分类及演化规律

TAXONOMY AND EVOLUTIONARY PROCESS OF NEOGENE BOVIDAE FROM CHINA

我国新近纪的牛科相当繁盛。至今已记录了30属,归入5个亚科(Hypsodontinae,Urmiatheriinae,Caprinae,Antilopinae和Bovinae)。化石主要出现在我国北方且大部分为土著类型,以颊齿中等高冠至高冠、前臼齿列短、头骨粗壮、弯曲和角心特化为特征。在整个新近纪时期,牛科经历了5个发展阶段和4次大的更替。与同时代欧亚大陆其他地区的牛科类群相比,中国牛科化石出现的时间早,且基本组成不同。在中新世,我国的牛科主要由Hypsodontinae,Urmiatheriinae,Caprinae的早期特化类型和Gazella组成,Boselaphini稀少并缺乏转角羚羊(Antilopinae);在上新世,除Gazella外,我国北方仍生活着Caprinae的一组土著类型。

Bovidae is one of the most diversified groups of Neogene mammals. The study of Chinese Neogene Bovidae traced back to the beginning of the 20^(th) century (Schlosser, 1903). During the 1920's and 1930's, Neogene bovid fossil collecting and describing reached a peak. From the 1950's on, not only some new bovid taxa have been reported based on the materials obtained from Northern and Southwest China, but also the systematic positions of some bovid genera have been revised by Chinese paleontologists.In this paper, we try to review the taxonomy based on the most recent progress. Till now, 30 genera belonging to 5 subfamilies of Bovidae have been recognized from Chinese Neogene (Table 1). Most of the genera were found from North China. There discovered few taxa from the Late Miocene of Southwest China.Analysis of the geological and geographical distribution of fossil Bovidae from China shows 5 evolutionary phases and 4 turnovers during the Neogene:Phase 1; Late Oligocene-Early Miocene. Fossil Bovidae is only represented by Sinopalaeoceros Chen, 1988 ( Hypsodontinae). It occurred in the Early Miocene of Qinghai and in the Late Oligocene of Xinjiang.Phase 2; Middle Miocene ( Tunggurian) . Bovids are characterized by the presence of Tur-cocerus K(o)hler, 1987 and Kubanotragus Sokolov, 1973. They distributed only in North China.Phase 3 : Late Miocene ( Bahean-Baodean) . Bovids are characterized by the flourishing of Urmiatheriini, and a specialized group belonging to Caprinae. Gazella ( Antilopinae) is also one of the most common genera. Phase 4: Early Pliocene. The dominant elements are Gazella and endemic forms of Caprinae.Phase 5 Late Pliocene. Bovids are characterized by the occurrence of extant genera and species, e. g. Ovis and Gazella subgutturosa.These phases also indicate 4 turnover events of bovid faunas during the Neogene.The first turnover event happened after the first phase, in between the Early and Middle Miocene. Sinopalaeoceros went extinct, and there occurred Turcocerus, which is the dominant element during the Middle Miocene in North China. The Middle Miocene/Late Miocene boundary witnessed the second remarkable turnover event of Bovidae. None of the Middle Miocene taxa survived into the Late Miocene. The third turnover event happened near the Miocene/Pliocene boundary. The diversified group Urmiatheriini went extinct. The fourth turnover event is characterized by the occurrence of extant genera and species during and after the Late Pliocene.Excluding the argued Palaeohypsodontus and Hanhaicerus, there recorded earlier bovid taxa in China than in other areas of Eurasian continent. The faunal composition of Chinese Bovidae during the Neogene is also distinct. Hypsodontinae, Urmiatheriinae, and endemic forms of Caprinae constitute the major part of Miocene bovid faunas. In other areas of Eurasia, Bovi-nae (including Eotragus, Boselaphini, Bovini) , spiral horned Antilopinae, and early forms of Caprinae are the dominants in the Miocene.There recorded two major immigration events of Bovidae during the Neogene, e. g. the immigration of Eotragus at MN 6, and Miotragocerus during the Late Miocene. However, these immigration events did not alter the endemic faunal composition of Chinese Bovidae.