Chronology of the early Pleistocene Orce and Huéscar sites (Baza Basin, SE Spain)

Abstract

The Baza Basin (SE Spain) preserves one of the most complete continental records of the European early Pleistocene and is central to debates on the timing of the first human dispersals into Western Europe. This study provides an updated chronological and biochronological framework for the key sites of Orce (Fuente Nueva-1, Venta Micena, Barranco León and Fuente Nueva-3) and the nearby locality of Huéscar-1. We integrate large and small mammal biostratigraphy with paleomagnetism and published numerical dating (ESR, U-series, and cosmogenic nuclides) to refine the temporal succession of faunal assemblages spanning the middlle Villafranchian to the Epivillafranchian. Fuente Nueva-1 is placed near the middle–late Villafranchian transition (ca. 2.1–2.0 Ma). Venta Micena records a derived post-Dmanisi fauna best dated to ca. 1.6–1.5 Ma. Overlying layers at Barranco León and Fuente Nueva-3, which have yielded lithic artefacts, cut-marked bones, and a human deciduous tooth, are slightly younger (ca. 1.5–1.3 Ma), documenting the earliest well-dated human presence in Western Europe. Faunal changes between Venta Micena and these sites indicate increasing environmental openness and aridity and the replacement of mesodont caprines by more hypsodont forms, together with equid diversification. Huéscar-1 represents a later Epivillafranchian community (ca. 1.07–0.8 Ma), characterized by more generalized taxa linked to the Early–Middle Pleistocene Transition. The combined evidence supports a diachronous sequence of faunal turnovers and confirms that hominins reached southwestern Europe before the return of suids at the onset of the Early-Middle Pleistocene Transition, constraining the ecological context of the earliest European populations.