Geological and palaeontological context of a Pliocene juvenile hominin at Dikika, Ethiopia

摘要

Since 1999, the Dikika Research Project (DRP; initiated by Z.A.) has conducted surveys and excavations in badlands that expose Pliocene and Pleistocene sediments south of the Awash River in Ethiopia, between surrounding hominin localities at Hadar(1), Gona(2) and the Middle Awash region(3). Here we report our geological mapping and stratigraphic measurement of the DRP area, and the context of a remarkably well-preserved skeleton of the earliest known juvenile hominin at the Dikika DIK-1 locality(4). Our mapping of the DRP area permits a complete definition of the hominin-bearing Hadar Formation and provides a cohesive structural and tectonic framework defining its relationships to adjacent strata. Our findings reveal the basin-scale tectonic, depositional and palaeoenvironmental history of the area, as well as a clear taphonomic and palaeontological context for the juvenile hominin. Such data are crucial for understanding the environmental context of human evolution(5,6), and can be integrated into larger-scale tectonic and palaeoenvironmental studies(7,8). Our basin-scale approach to palaeoenvironments provides a means to elucidate the complex geological history occurring at the scale of temporally and geographically controlled fossil point localities(3,9-11), which occur within the rich tectonic and depositional history of the Awash Valley.