New cranium of the large cercopithecid primate Theropithecus oswaldi leakeyi (Hopwood, 1934) from the paleoanthropological site of Makuyuni, Tanzania.

The Pleistocene hominin site of Makuyuni, near Lake Manyara, Tanzania, is known for fossils attributable to Homo and Acheulean artifacts (Ring et al., 2005; Kaiser et al., 2010; Frost et al., 2012). Here we describe the fossil primate material from the Manyara Beds, which includes the first nearly complete female cranium of Theropithecus oswaldi leakeyi and a proximal tibia from the same taxon. The cranium is dated to between 633 and 780 Ka and the tibia to the Pleistocene. The T. oswaldi lineage is one of the most important among Neogene mammals of Africa: it is both widespread and abundant. The size of the dentition, cranium, and tibia all confirm the previously recognized trend of increasing body size in this lineage and make their taxonomic assignments secure. The morphology of this specimen provides new insights into the evolution of this lineage through time, as well as its geographic variation and sexual dimorphism. The cranium also shows damage consistent with a mammalian carnivore, most likely a felid. The identification of this material as representing T. o. leakeyi agrees with the Middle Pleistocene age estimates for the MK4 locality in particular and the Manyara Beds in general.

Refined age estimates and Paleoanthropological investigation of the Manyara Beds, Tanzania.

The Manyara Beds in the area of Makuyuni Village in the Lake Manyara Basin, Tanzania have been studied for nearly a century, but interpretations of their age have ranged from Middle Pleistocene to Late Pliocene. New geological, paleontological and archeological fieldwork was conducted at the site and has provided siginificant new evidence, including refined stratigraphy, radiometric age estimates, preliminary paleomagnetic analysis, significant new faunal collections, as well as stratigraphic context for some of the lithic artifacts in stratigraphic context. These efforts have succesfully constrained the geological age estimates for the Manyara Beds to between less than 0.63 to 1.3 Ma, and the age of the two hominin bearing localities to between 0.63 and 0.78 Ma. This new chronology may impact the taxonomic interpretation of the hominin remains recovered from the site. They also suggest that two mammalian taxa, Metridiochoerus compactus and Eurygnathohippus, may have some of their youngest known occurences in the Manyara Beds. Acheulean lithics were also found in stratigraphic context during this more narrow time interval. Furthermore, the presence of potential cut-marks on the surface of a bovid mandible may represent the first evidence for human modification of bones from the Manyara Beds.