Palaeoecological reconstructions are fundamental for the understanding of interactions between all the mammalian communities in a given environment and their choices in terms of habitat, diet and migrations. During the Late Pleistocene in north western Europe, hyenas and human groups shared essentially the same ecological niche. A comparison of their crossed relationships could therefore yield important data on the palaeoecological context. Unfortunately, numerous Palaeolithic sites in north western Europe were excavated well before modern archaeological techniques were devised. Thus the faunal assemblages collected during those early excavations do not have any stratigraphic context and the results extracted from these collections by classical approaches are therefore limited. However, in the karstic region of the Meuse Valley (southern Belgium), many sites have yielded massive amounts of archaeological and palaeontological material dated to the MIS 3. One of the challenges of this on-going doctoral research is to attempt to study this area by attempting an ecological reconstruction based on these old faunal collections in order to highlight settlements and dispersions of the MIS 3 key-species like ungulates, carnivores and humans.