New interpretation of the Gran Dolina-TD6 bearing Homo antecessor deposits through sedimentological analysis

I Campaña,E Carbonell,J M Bermúdez De Castro,A Pérez-González,J Rosell,R Blasco,A Benito-Calvo,J L Arsuaga

doi:10.1038/srep34799

Abstract

Gran Dolina is a cavity infilled by at least 25 m of Pleistocene sediments. This sequence contains the TD6 stratigraphic unit, whose records include around 170 hominin bones that have allowed the definition of a new species, Homo antecessor. This fossil accumulation was studied as a single assemblage and interpreted as a succession of several human home bases. We propose a complete stratigraphic context and sedimentological interpretation for TD6, analyzing the relationships between the sedimentary facies, the clasts and archaeo-palaeontological remains. The TD6 unit has been divided into three sub-units and 13 layers. Nine sedimentary facies have been defined. Hominin remains appear related to three different sedimentary facies: debris flow facies, channel facies and floodplain facies. They show three kinds of distribution: first a group of scattered fossils, then a group with layers of fossils in fluvial facies, and third a group with a layer of fossils in mixed fluvial and gravity flow facies. The results of this work suggest that some of these hominin remains accumulated in the cave by geological processes, coming from the adjacent slope above the cave or the cave entry, as the palaeogeography and sedimentary characteristics of these allochthonous facies suggest.

Highlights

TD6 is surely the most well-known lithostratigraphic unit in the Gran Dolina site
The first excavation was during the 1994–1995 field seasons, in a test pit of approximately 6 m2, where several hominin remains and lithic artefacts were recovered from a distinctive layer named the “Aurora Stratum”[1,26]
The test pit was situated in the south of the Gran Dolina site (Fig. 1) and its south-east area was affected by cut-and-fill, with loss of information over about 1 meter diameter of the test pit

Summary

Introduction

TD6 is surely the most well-known lithostratigraphic unit in the Gran Dolina site. Human and non-human remains there have been the main focus of a number of studies[1,2,3,4,5,6,7,8], which have enriched our knowledge about the human lineage during the Early Pleistocene and the palaeoecological context. The opening of the Gran Dolina cavity to the outside during the Early Pleistocene[10] resulted in allochthonous sediment input and the accumulation of archaeo-palaeoanthropological remains. These sediments have been differentiated into 12 lithostratigraphic units[11,12]. The second excavation began in the first decade of the present century This excavation area had a triangular shape of 13 m2, and was situated in the central area of the Gran Dolina section (Fig. 1), where medial sedimentary facies appear. H. antecessor is characterized by a combination of primitive traits shared with early Homo, primitive traits retained by modern humans, and derived traits shared with modern humans[2,3,27]. The particular combination of features found in H. antecessor allows to assume that this species is close to the last common ancestor of Neanderthals and modern humans[30]

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Conclusion