The first Paranthropus from the Malawi Rift

The Hominid Corridor Research Project (HCRP) began a long-term study of the Malawi Rift in 1983, focusing on the role played by south-eastern Africa i n the origin and dispersion of Plio-Pleistocene faunas, including early hom inids (Schrenk et al., 1993; Bromage & Schrenk, 1995; Bromage et al., 1995a ). The sample of vertebrates recovered from the Chiwondo Beds of Northern M alawi now includes about 1000 identifiable vertebrate specimens from 145 fo ssil localities between the Mwangwabila and Remero Rivers in the north, and in the vicinity of Uraha Hill in the south. The sedimentology and stratigraphy was described by Ring & Betzler (1995) a nd Betzler & Ring (1995). Lake beds and fluviatile deposits of paleolake Ma lawi have been subdivided into five depositional units which are bounded by unconformities reflecting sedimentary breaks. Prior to the formation of a major perennial lake, the area was characterized by extensive fluviatile de posits mainly formed by the reworking of material from Jurassic red beds. F ormation of a major lake after this episode is reflected in widespread lacu strine silts and sands with interbedded mollusc-rich layers. Tectonic reorg anization of the Rift finally led to localized uplift, resulting in an angu lar unconformity and exposure of the Plio-Pleistocene deposits. Most of the Late Pliocene fossil localities are attributed to stratigraphic Unit 3A, while older Middle Pliocene localities occur in stratigraphic Uni t 2 in the north and the south. An age determination of greater than 4.0 Ma to ca. 1.5 Ma for Units 2 and 3A is based on their respective faunal assem blages (Schrenk et al., 1993; Bromage et al., 1995a). Terrestrial vertebrat e fossils dominate the collections made from the interbedded soft sandstone s, and fresh water molluscs are limited to the consolidated beds of carbona te cemented sandstone. Most of the mammal remains are collected from the su rface of the sediments by systematic surveys. Because of the very low fossi l density-on average one fossil per 1 km(2)-systematic excavations took pla ce only at those localities where a high concentration of surface finds ind icates an accumulation of fossils in a certain horizon. One such fossil-rich horizon was identified at Malema. The discovery of the second hominid from the Chiwondo Beds at Malema demonstrates the importanc e of this locality within the Malawi Rift deposits, since, like the early H omo discovery, it also derives from Unit 3A. The geographic position of the Chiwondo Beds in southeastern Africa has the potential to provide (C) 1999 Academic Press.