HRRBAA: Paleontology and paleoanthropology of a potential Late Miocene site in the Laikipia highlands

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The period between 11.6 - 5.33 million years ago (the Late Miocene) was a major turning point in human and ape evolution, with the human, gorilla, and chimpanzee lineages all originating during this interval. The recognizable fauna of the African savanna as we know it - dominated by elephants, zebras, and many kinds of antelopes - was also established during this critical interval of environmental change, characterized by expanding C4 vegetation (predominantly grasses). Despite the importance of the Late Miocene in human and mammalian evolution, the fossil record from the Late Miocene in eastern Africa is restricted to only a handful of sites in the East African Rift System (EARS). This high-risk research project will improve our understanding of human and mammalian evolution in the Late Miocene by developing the scientific potential of a newly discovered fossil site called Tumbili Estate, located outside the EARS in the highlands of Laikipia County, Kenya. This project will provide research experience for American and Kenyan undergraduate and graduate students, which will bolster the researcher pipeline and lead to a more globally engaged workforce. Through our partnership with the Laikipia Forum, a consortium of local Kenyan stakeholders, this project will enhance the understanding of human evolution among community members, and give local people a voice in the science being conducted on their land. DNA evidence has firmly established that the human, gorilla and chimpanzee lineages originated during the Late Miocene. However, the fossil evidence for the origin of these lineages is meager. The known ape fossils from the Late Miocene are fragmentary, and the potential links between the fossils and the modern apes are largely unknown. The recovery of additional fossil ape and/or hominin (i.e., human ancestor) fossils from this time period is the key to understanding the origin of the hominin, gorilla, and chimpanzee lineages. This research project will confirm the age and extent of sediments at the Tumbili Estate, which likely date between 9 - 10 Ma based on fossils previously recovered, and also allow survey of nearby areas for additional sites. Analysis of the paleoenvironment at Tumbili will provide valuable new data bearing on the timing of the C4 vegetation expansion and the modernization of the African mammalian fauna. The fact that Tumbili is located on a high-elevation plateau far outside the EARS will add significantly to our understanding of the spatial and altitudinal variation of the habitats on the landscape during the Late Miocene.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.