Small mammals as tools to characterize archaeological contexts in the Chalcolithic of El Portalón site (Atapuerca, Burgos, Spain)

Abstract

El Portalón is the current entrance to the Cueva Mayor Karst system of the Sierra de Atapuerca (Burgos, Spain). The latter is internationally well-known for its rich Early to Middle Pleistocene hominin-bearing localities. Besides, El Portalón is an important archaeological site with a long stratigraphic sequence roughly covering the last 30.000 years (latest Pleistocene-Holocene). The Holocene deposits, which document intense human activity, have been divided into nine chrono-cultural units comprising the Mesolithic, Neolithic, Chalcolithic, Bronze Age, Iron Age, Roman, and Medieval periods. We present for the first time the small-mammal assemblage from three different archaeological contexts of the Chalcolithic occupation of El Portalón: the prepared soil, the unprepared soil and the “Fumiers”. The complete set of small mammals from the Chalcolithic of El Portalón includes four insectivores (Sorex minutus, S. gr. araneus-coronatus, Crocidura russula, and Talpa sp.), nine rodents (Apodemus sylvaticus, Microtus [Terricola] lusitanicus, M. [T.] duodecimcostatus, M. [Microtus] arvalis, M. [M.] agrestis, Chionomys nivalis, Arvicola sapidus, Sciurus vulgaris, and Eliomys quercinus), one undetermined leporid, and two chiropterans (Miniopterus cf. shreibersi and Myotis gr. myotis/blythii). The sediment of the prepared soil, allochthonous in origin, also contains Pliomys lenki, but this species surely corresponds to a contamination from the Pleistocene. Fossil small mammals have been traditionally used for biochronology and palaeoenvironmental reconstructions. Here, slight but meaningful quantitative and qualitative differences among contexts in terms of their small-mammalian contents are used as effective tools to characterize them both chronologically and taphonomically.