New dating results at Incarcal‐I (Spain) shed light on the exceptionally rich late Early Pleistocene fossil record of the Iberian Peninsula

Abstract

More than five decades after the first report of fossil remains found in a limestone quarry near Crespià, NE Spain, we provide here the first dating results for the palaeontological assemblage from Incarcal‐I, one of the various fossil‐rich sinkholes identified at the locality that has yielded ~2,000 remains representing at least 15 taxa of large mammals. Palaeomagnetism in conjunction with combined U‐series and electron spin resonance (ESR) dating of fossil teeth consistently constrain the age of Incarcal‐I to the latest part of the Early Pleistocene. Specifically, with palaeomagnetic results showing reverse magnetic polarities for the large majority of the samples and no indisputable evidence of normal polarity in the stratigraphic succession, the deposits may be reasonably correlated to the Matuyama Chron (2.61–0.77 Ma), thus providing a minimum age constraint of 0.77 Ma for the sedimentary infill. Additionally, direct dating of two fossil teeth of Hippopotamus antiquus using the most advanced analytical procedures, through a combination of unusually high sampling density ( n = 17) for bulk ESR and U‐series analyses and high‐resolution laser ablation Inductively Coupled Plasma‐Mass Spectrometry (ICP‐MS) analyses, yields a mean age of 862 ± 52 ka (1σ). Interestingly, the data set collected shows the exceptionally high spatial homogeneity of the ESR and U‐series data across dental tissues and of the natural radioactivity of the sedimentary environment. Furthermore, the uncertainty around the uranium uptake modelling carries very little weight in the age calculation, which is unusual for such old fossil teeth. Consequently, this set of evidence supports the robustness and reliability of the ESR chronology, adding a new solid chronological tie point for biochronological inferences. In summary, the various lines of evidence available enable confident positioning of Incarcal‐I in the latest part of the Early Pleistocene, that is, somewhere between the end of the Jaramillo Subchron (1.01 Ma) and the Matuyama–Brunhes boundary (0.77 Ma). The numerical dating results indicate that the fossil assemblage of Incarcal‐I is coeval with those from other well‐constrained key Spanish localities such as Atapuerca Gran Dolina TD4‐6, and Vallparadís Station EVT7, highlighting the overall exceptional density of the Iberian fossil record between ~0.8 and ~1.0 Ma. Finally, a critical evaluation of the existing age constraints available for the Calabrian (1.80–0.77 Ma) fossil localities of the Iberian Peninsula is also proposed here, with a first tentative classification of the sites into four main categories (A to D) based on the robustness and precision of their chronostratigraphic framework.

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