Late Middle Pleistocene malacofauna of the Acheulean site of Valdocarros II, Jarama river valley, Madrid, Spain

Abstract

ing to its geographical position relative to northwestern Europe, the Iberian Peninsula was a refuge for many species during periods of harsh environmental conditions in the Quaternary. Despite this, the Pleistocene history of non-marine molluscs in Spain has been scarcely addressed. In this study, we examine the malacofauna of Valdocarros II, a site within the Complex Terrace of Arganda in the Jarama river valley tributary of the Tagus River in central Spain. This large, minutely-excavated site consists of five flood sequences identified in five archaeological levels and has been dated to the late Middle Pleistocene (end MIS 8–beginning MIS 7). Specimens of twelve freshwater and eighteen land mollusc taxa were identified. The most abundant species observed was Xerotricha madritensis, a land snail endemic to the Iberian Peninsula that today inhabits exposed surfaces with scarce plant cover. The most abundant freshwater species found was Anisus spirorbis, which currently thrives in tributaries of the Jarama River. This malacofauna assemblage features different ecological components, though dry, open-ground terrestrial species predominate. A correspondence analysis of the most frequently appearing land animals and the archaeological levels revealed a slight separation of level 2 from the other levels, indicative of its mesophilous character. However, few differences among these levels were identified in three correspondence analyses performed on the land or freshwater species datasets. Our observations of the malacofauna assemblage of Valdocarros II indicate a site characterized by a temperate climate and open areas with riverside vegetation. Furthermore, we propose the assignment of this site to an interstadial given the observed malacofauna of the five levels.