Small vertebrate remains found in archaeological context are of particular interest as they bring precise information on the palaeoenvironmental context of human occupations. However a taphonomic analysis of the fossil assemblages is necessary to get information on the origin of the accumulations and the deposits formation, as well as on possible biases of anatomical and/or faunal representation affecting the palaeoecological interpretations. In the present paper we consider two case studies from northern France, a region remaining poorly considered for small vertebrate studies. The Carpentier Quarry (Abbeville, Somme) has yielded Middle Pleistocene occupations attributed to Homo heidelbergensis (~600 ka BP), while Mützig (Alsace) is a Late Pleistocene site having been occupied by Neanderthals (~90 ka BP). We do not discuss here the chronological or cultural attribution of the two sites, but only the taphonomic pattern delivered by small vertebrate assemblages in order to better understand the sites formation within their own geographic and geologic contexts, including comparison with data from other disciplines (large mammals, infilling). Several differences emerge between the two sites, as well as within each site, highlighting post-depositional perturbations in some levels. In these levels we thus should be cautious about palaeoenvironmental conclusions deduced directly from the faunal lists, and suggest detailed comparison between data provided by small vertebrates with other disciplines for greater reliability.