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Middle Miocene hominoid Nacholapithecus and hominoid evolution

中新世人科动物 Nacholapithecus 和人科动物进化

基本信息

批准号：
13375005
负责人：
ISHIDA Hidemi
金额：
$ 22.05万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Human origin is an extension of evolutions of the middle so Miocene hominoids. Elucidating the evolutional processes of the Miocene hominoids is thus essential to understand the mechanism of the human origin. In this study, we have excavated e Site BG-K in Nachola, northern Kenya, whore many hominoid fossils wan empirically expected to be found, and conducted accompanying geological anti palaeontological surveys.Basaltic lava bed overlying the fossil containing sediments was removed at BG-K and we excavated 632m^2 in the year 2001, and 824m^2 in 2002. We firstly excavated relatively soft, 2m deep silt layer, and then hard, 20cm thick shale layer below the silt layer. The latter contained more fossils bat it is so hard that we had to collect anti bring all blocks containing fossils back to Kenya National Museum in Nairobi foes removal of matrix by skillful technicians.As a consequence, we collected more than 500 fossil specimens, including skulls, of the 15 million year old large homino … More id, Nacholapithecus. Morphological features of the fossils showed that is was not so differentiated as the 17 million year old Miocene hominoid, Afropithecus, suggesting that Nacholapithecus a common ancestor of later hominoid and human clades. Its locomotor behavior was also considered to be derived towards the extant hominoids. Development of forelimb was more prominent in Nacholapithecus thus in the preceding Miocene hominoid, Proconsul.Three fifth of the excavation at the Site BG-K has been unfinished. We will complete the excavation and detailed analyses of the specimens and plan to publish a monograph on Nacholapithecus in near future. There is no other group in the world who excavated fossils of a single species as abundantly as our group did. Moreover, our specimens include its whole skeleton and ace generally in excellent condition. Therefore, we will be able to thaw the entire picture of Nacholapithecus, a typical middle Miocene hominoid. Our achievements will be highly appraised internationally. Less

人类的起源是中至中新世古人类进化的延伸。因此，阐明中新世类人猿的进化过程对于理解人类起源的机制至关重要。本研究对肯尼亚北部Nachola的BG-K遗址进行了挖掘，发现了许多经验上预计会发现的类人猿化石，并进行了相应的地质和古生物调查。在BG-K，我们对覆盖在含化石沉积物上的玄武岩熔岩层进行了清除，2001年挖掘了632m^2, 2002年挖掘了824m^2。我们先开挖较软的，2m深的粉砂层，然后在粉砂层下面开挖较硬的，20cm厚的页岩层。后者包含了更多的化石，但由于难度太大，我们不得不收集并将所有包含化石的块带回内罗毕的肯尼亚国家博物馆，并由熟练的技术人员去除基质。因此，我们收集了超过500个化石标本，包括1500万年前的大型人猿的头骨。化石的形态特征表明，其与距今1700万年前的中新世古人类非洲猿人（Afropithecus）差异不大，表明Nacholapithecus是后来的古人类和人类分支的共同祖先。它的运动行为也被认为是向现存的类人猿进化而来的。前肢的发育在Nacholapithecus中更为突出，因此在之前的中新世人科动物Proconsul中。BG-K遗址五分之三的挖掘工作尚未完成。我们将完成对这些标本的挖掘和详细分析，并计划在不久的将来出版一本关于Nacholapithecus的专著。世界上没有任何一个群体像我们这样发掘出如此丰富的单一物种化石。此外，我们的标本包括它的整个骨架，总体上保存完好。因此，我们将能够解冻Nacholapithecus的整个画面，这是一个典型的中新世中期类人猿。我们的成就将在国际上得到高度评价。少