The Omo-Turkana Basin of southern Ethiopia and northern Kenya preserves a rich record of late Cenozoic fossil vertebrates and plays a central role in our understanding of early hominin evolution. In this chapter we focus on the northern area of the basin, the lower Omo Valley of Ethiopia. We provide a brief history of research in the area, present a review of previous studies focused on the paleoenvironments of the Shungura Formation (Figure 24.1), and offer a fresh perspective for the paleoecological context of hominin evolution in the lower Omo Valley with analyses of mammalian diversity and faunal similarity patterns from ~3.6 to 1 Ma.