Homogeneity of fossil assemblages extracted from mine dumps: an analysis of Plio-Pleistocene fauna from South African caves

Mine dumps associated with limestone cave deposits are common in dolomitic areas of southern Africa. The dumps often contain blocks of breccia, which are rich in micro-mammalian fossils (especially rodents, shrews and bats). Unfortunately, these fossiliferous breccia blocks are out of geological and stratigraphic context. Nevertheless, they provide a large amount of palaeontological material of great interest. In order to use this kind of material, a first approach is to test for homogeneity of the fossil assemblages extracted from the breccia blocks. Fisher's exact test can be used. Two analyses were undertaken. The first was performed on block samples taken in situ from breccia at the Drimolen hominid site. The results indicated that the samples were homogenous, as expected. The second analysis was carried out on different samples extracted from blocks of breccia collected from a dump at the Gondolin site. The results show that it is possible to group several samples in a single representative assemblage. Some blocks could be grouped together and then used to address taphonomic issues. Once these problems are solved, the data set can be used with greater confidence to address matters concerning palaeoenvironmental reconstructions associated with Plio-Pleistocene hominids.