Publication: Luminescence dating and palaeomagnetic age constraint on hominins
from Sima de los Huesos, Atapuerca, Spain
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Publication Date
2014
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Elsevier Science B.V., Amsterdam
Abstract
Establishing a reliable chronology on the extensive hominin remains at Sima de los Huesos is critical for
an improved understanding of the complex evolutionary histories and phylogenetic relationships of the
European Middle Pleistocene hominin record. In this study, we use a combination of ‘extended-range’
luminescence dating techniques and palaeomagnetism to provide new age constraint on sedimentary
infills that are unambiguously associated with the Sima fossil assemblage. Post-infrared-infrared stimulated
luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated
luminescence (TT-OSL) dating of individual quartz grains provide weighted mean ages of 433 � 15 ka
(thousands of years) and 416 � 19 ka, respectively, for allochthonous sedimentary horizons overlying the
hominin-bearing clay breccia. The six replicate luminescence ages obtained for this deposit are reproducible
and provide a combined minimum age estimate of 427 � 12 ka for the underlying hominin
fossils. Palaeomagnetic directions for the luminescence dated sediment horizon and underlying fossiliferous
clays display exclusively normal polarities. These findings are consistent with the luminescence
dating results and confirm that the hominin fossil horizon accumulated during the Brunhes Chron, i.e.,
within the last 780 ka. The new bracketing age constraint for the Sima hominins is in broad agreement
with radiometrically dated Homo heidelbergensis fossil sites, such as Mauer and Arago, and suggests that
the split of the H. neanderthalensis and H. sapiens lineages took place during the early Middle Pleistocene.
More widespread numerical dating of key Early and Middle Pleistocene fossil sites across Europe is
needed to test and refine competing models of hominin evolution. The new luminescence chronologies
presented in this study demonstrate the versatility of TT-OSL and pIR-IR techniques and the potential
role they could play in helping to refine evolutionary histories over Middle Pleistocene timescales.