Study on origins of man and living apes in East Africa

正如我们项目的标题所示，主要目标是弄清楚原始人的起源和现代非洲猿的起源。最初，我们计划在肯尼亚和扎伊尔进行实地调查。前者是发现原始人的化石，后者是发现黑猩猩和大猩猩的祖先。然而，扎伊尔的政治局势自1991年春末以来更糟。因此，我们停止了在扎伊尔的实地调查。在肯尼亚研究的地区是Samburu Hills和Nachola地区。在地层学基础上，该区新近系由高到低划分为7组：Nachola F. （19-15Ma）、Aka Aiteputh F. （15-10Ma）、namurungulle F. （10-7Ma）、Nanyangaten-Kongia F. （7-5Ma）、tir - tir F. （4Ma）。从地质和年代学资料来看，纳慕伦居勒组与南扬噶顿组之间存在极其明显的构造缺口，表明纳丘拉组、阿卡艾特普斯组和纳慕伦居勒组断层较多，而南扬噶顿组上部构造断层较少。下三组断裂标志着9 ~ 8 Ma的裂谷系大构造运动。在那慕伦格勒地层中发现了大量的马科动物和牛科动物的遗骸。这些分类群标志着开阔林地环境向稀树草原环境的转变。看来那慕伦居勒动物群可能是撒哈拉以南热带草原和林地环境中现代动物群的先驱。在地层中发现了一种大型类人猿，桑布鲁-类人猿。类人猿可能是陆地上用指关节行走的动物或两足动物。对于原始人起源的讨论，人们强烈期望有更多的原始人发现。

As shown in the title of our project, the major objectives have been to make clear the origin of hominids and origin of modern African apes. Originally, we had planned to conduct field surveys in Kenya and Zaire. The former was to discover fossils of proto-hominids, and the latter was to discover ancestors of chimpanzees and gorillas. A political situation of Zaire, however, has been worse since late spring of 1991. Therefore, we stopped having the field survey in Zaire. The areas studied in Kenya are Samburu Hills and Nachola area.On the basis of stratigraphy, the Neogene System in the areas is divided into following seven formations in ascending order : Nachola F. (19-15Ma), Aka Aiteputh F. (15-10Ma), Namurungule F. (10-7Ma), Nanyangaten-Kongia F. (7-5Ma), and Tirr-Tirr F. (4Ma). From the geological and geochronological data, an extremely marked structural gap is recognized between the Namurungule and Nanyangaten formations indicating many faults in Nachola, Aka Aiteputh and Namurungule formations but few in the upper formations from Nanyangaten Formation. The faults in the lower three formations is indicating a major tectonic movement of rift system in age from 9 to 8 Ma.The numerous equid and bovid remains have been found from the Namurungule Formation. These taxa indicates the open woodland to savanna environments. It seems that the Namurungule Fauna might have been the forerunner of the modern Sub-Saharan fauna in savanna and woodland environments. A large hominoid, Samburu-hominoid, was discovered from the formation. The hominoid might have been terrestrial knuckle-walkers or bipeds. Additional discoveries of the hominoids are strongly expected for a discussion of the origin of hominids.