Early-Middle Pleistocene freshwater ecosystems in the Sierra de Atapuerca (northern Iberia) based on the Gran Dolina fish record

Abstract

Fish bones are common in Pleistocene cave deposits in Europe. In this paper, we report on fish remains from the Gran Dolina cave (Trinchera del Ferrocarril) in the Sierra de Atapuerca in Spain, to increase what is known of the freshwater ecosystems close to the cave. The 19-m-thick section, divided into 11 stratigraphic levels, represents an Early to Middle Pleistocene time span as dated by biostratigraphy, ESR, U-series, and magnetostratigraphy. We focus on the Sondeo South site, excavated from 1993 to 1999, which has yielded 1087 fish bones comprising the following taxa: brown trout (Salmo trutta), the common European eel (Anguilla anguilla) and chub (Squalius sp.). Taphonomic studies suggest that the European eagle owl (Bubo bubo) was the most likely predator responsible for the accumulation. Changes observed in the body size of brown trout through the sequence cannot be attributed to climate change (contravening Bergmann's rule). Our study documents the presence of a pre-mountain river system characterized by permanent, oxygen-rich, relatively cold flowing waters around the Sierra de Atapuerca during Early-Middle Pleistocene times.