Australopithecussediba from Malapa, South Africa
First discovered in August of 2008, the site of Malapa, South Africa revealed two relatively complete partial skeletons that we assigned to a new species, Australopithecus sediba. Additional individuals have since been detected, and await excavation at the site. It appears that these hominins were washed into the cave through a deep vertical shaft, likely in a single depositional event resulting from a large storm inflow. Burial and cementation were rapid, occasioning the exceptional preservation of these skeletons. Uranium-lead and paleomagnetic dating combine to precisely constrain the age of the site to 1.977 ± 0.0015 Ma. Cranial and postcranial remains of A. sediba demonstrate numerous australopith-like features that denote a hominin at an australopith adaptive grade, prompting its inclusion in the genus Australopithecus. However, A. sediba also displays a series of characters that align it more closely with Homo than any other australopith species. We consider the evidence supporting the appearance of Homo prior to 1.977 Ma to be inconclusive, therefore we hypothesize that A. sediba from Malapa could be ancestral to Homo. Alternatively, if the existence of Homo prior to 1.977 Ma can be confirmed, this would not preclude a population of A. sediba that predated Malapa from occupying this role. Therefore we hypothesize that A. sediba indeed represents the ancestor of the genus Homo.
KeywordsHomo Skeletal morphology Taxonomy
We would like to thank our exceptional fossil preparation team, including C. Dube, B. Eloff, C. Kemp, M. Kgasi, M. Languza, J. Malaza, G. Mokoma, P. Mukanela, T. Nemvhundi, M. Ngcamphalala, S. Jirah, S. Tshabalala, and C. Yates, our chief preparator. Other individuals who have given significant support to this project include B. de Klerk, C. Steininger, B. Kuhn, L. Pollarolo, B. Zipfel, J. Kretzen, D. Conforti, J. McCaffery, C. Dlamini, H. Visser, R. McCrae-Samuel, B. Nkosi, B. Louw, L. Backwell, F. Thackeray, and M. Peltier. We also thank E. Mbua, P. Kiura, V. Iminjili, and the National Museums of Kenya for access to comparative specimens in their care. S. Potze and T. Perregil facilitated access to the fossil hominins of the Ditsong Museum (formerly Transvaal Museum). T. Stidham assisted with the cladistic analysis of the Malapa hominins. J. Smilg facilitated CT scanning of the specimens. R. Clarke and F. Kirera provided valuable discussions on these and other hominin fossils in Africa. We would like to thank the South African Heritage Resource agency for the permits to work on the Malapa site and the Nash family for granting access to the Malapa site and continued support of research on their reserve. The University of the Witwatersrand’s Schools of Geosciences and Anatomical Sciences and the Bernard Price Institute for Palaeontological Science provided institutional support and facilities, as did the Gauteng Government, Gauteng Department of Agriculture, Conservation and Environment, and the Cradle of Humankind Management Authority. The South African Department of Science and Technology, the South African National Research Foundation, the Institute for Human Evolution (IHE), the Palaeontological Scientific Trust (PAST), the Andrew W. Mellon Foundation, the Africa Array Program, the United States Diplomatic Mission to South Africa, Duke University, the Ray A. Rothrock Fellowship of Texas A&M University, the Texas A&M Program to Enhance Scholarly and Creative Activities, the University of Zurich 2009 Field School, and Sir Richard Branson all provided substantial funding for the excavations and research conducted at Malapa.
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