Fauna, taphonomy, and ecology of the Plio-Pleistocene Chiwondo Beds, Northern Malawi

Abstract

The vertebrate fauna of the Chiwondo Beds in Northern Malawi is heavily biased towards the preservation of large terrestrial mammals, the majority being ungulates. The faunal diversity resembles an African shortgrass plains assemblage. The taxonomic diversity is nevertheless low, emphasizing an incomplete fossil record. Based on modern bovid representation in African game parks, statistical tests show that the Chiwondo bovid assemblage consists of a mixture of species found in the Somali-Masai and the Zambezian ecozones. The composition of the terrestrial fauna is similar to Swartkrans 1 and the Upper Ndolanya Beds. The fossil assemblages can be assigned to three biostratigraphic time intervals that date from older than 4.0 Ma to less than 1.5 Ma. The occurrence of Paranthropus boisei at a lake margin site in the Chiwondo Beds corresponds to robust australopithecine-bearing localities near Lake Turkana, Kenya. A case study showed that the investigated death assemblage on a delta plain in the Malema region was subject to heavy modification after deposition. This has affected the size distribution, the frequencies of skeletal elements, and thus the taxonomic composition. High-density skeletal elements such as molars and partial mandibles dominate the assemblage. The Homo rudolfensis locality at Uraha has a different faunal composition, the preservation in a paleosol points to a different taphonomic history and the Uraha area encompasses a longer time span.