Study of hominoid evolution and human origin in East Africa

尽管东非中新世中晚期的化石证据在类人猿进化和人类起源中起着重要作用，但仍然很少。因此，这个时代被称为人类进化史上“化石证据的巨大缺口”。该项目专注于这个尚未被发现的时期，并进行了多年的挖掘。2000年，按照初步研究建议的计划，在肯尼亚北方的Nachola和Samburu山进行了挖掘和地质调查。研究结果如下：纳乔拉是一个化石非常丰富的地区，采集到了丰富的化石标本。我们在BG-K化石点进行了大规模的发掘，在那里收集到了大量的凯里那古猿的新属和新种。我们收集了更多的化石标本，并移除了覆盖化石沉积物的部分风化玄武岩层。工作区南北长160米，东西长30米。玄武岩层厚5米。劳动力开采的玄武岩砂和岩石总量约为10，000吨。2001年田间季节的设置就这样完成了。新的化石标本数量超过50件。在桑布鲁山的Nakapoleterado河和Moru Abeyo地区进行了地质调查。在接下来的几个季节里，预计将在BG-K化石遗址出土大量的克里氏那古猿标本。一群个体可以提供线索来揭示这个化石类人猿的社会结构。

Despite its central role for the evolution of hominoids and human origins, fossil evidences from middle-to-late Miocene from east Africa are still scarce. Hence, this age is colled the 'great gap of fossil evidence" in human evolution. This project has focused on this yet-to-known tie period and conducted excavations for years. In 2000, excavations and geological surveys have been conducted in Nachola and Samburu Hills, northern Kenya as had been planned in the initial research proposal. Results of the research are as follows.Nachola is a very fossil rich area and abundant fossil specimens have been collected. We did and extensive excavation at the BG-K fossil Site, where the bulk of hypodigm of Nacholapithecus kerioi, new genus and species has been collected. We collected additional fossil specimens and removed a partly weathered basalt layer which covers the fossil bearing sediments. The work area is 160m north to south and 30m east to west. The layer of basalt is 5m in thickness. The total amount of the basaltic sand and rock taken by labors is about 10,000 tons. The setting for the 2001 field season is thus completed. Number of the new fossil specimens exceeded 50.Geological survey in Samburu Hills has been conducted at river Nakapoleterado and Moru Abeyo areas. Taphonomic analyses have been done to investigate the duration and the pattern of the sediment formation.In the forthcoming seasons, it is expected that numerous Nacholapithecus kerioi specimens will be unearthed from the BG-K Fossil Site. One troop of individuals could give a clue to reveal the social structure of this fossil hominoid.