Museo de San Isidro

Abstract Understanding formation processes is crucial for interpreting sites with complex sedimentary histories and exceptional archaeological records, such as Level 3 of Des-Cubierta Cave. This Middle Paleolithic unit contains an assemblage of anthropically modified ungulate horned crania, Mousterian lithics, and evidence of fire use, all preserved in a clast-supported gravel deposit shaped by successive rockfalls. This study integrates geostatistical analyses with traditional spatial and taphonomic methods to examine the cone-shaped sedimentary structure that dominates the level and its influence on the spatial distribution and preservation of archaeological materials. The results reveal distinct spatial patterns for geological and archaeological materials, indicating separate formation dynamics. Size-based spatial analyses of boulders characterize the morphology of the conical structure, highlighting size sorting and intensity variations that may indicate sedimentary hiatuses. Bone refitting analysis suggests limited post-depositional movement, with material distribution shaped by the conical sedimentary structure and karst gallery morphology. Variability in crania preservation correlates with proximity to the cone’s apex and elevation, with better-preserved specimens in central areas and more fragmented remains in zones affected by erosive and edaphic processes. These findings underscore the value of integrating geostatistical and traditional archaeological approaches to advance interpretations of spatial and temporal patterns in karst environments and provide a methodological approach for examining sites with similar sedimentary histories. Moreover, the results support the interpretation of a recurrent, culturally motivated Neanderthal behaviour centred on the deliberate accumulation of large ungulate crania, pointing to a symbolic dimension in these practices.

Bone weathering constitutes a highly informative and commonly studied variable in taphonomic analyses. Vertebrate paleontologists, zoo-archeologists and forensic anthropologists have used weathering as a taphonomic clock to ascertain the exposure time of a bone assemblage before burial. Given that climatic conditions largely govern the weathering process, it is essential to investigate the effects of weathering across various climatic settings. This study analyzes the bone weathering process at Doñana National Park (Spain), a Mediterranean climate area. In 2018, we set an experiment in which four bones, three tibias and one skull, belonging to the main ungulates from Doñana (red deer, fallow deer, horse and wild boar) were placed in an enclosure and exposed to the natural environmental conditions. We present here results after almost 6 years of exposure. Over the study period, the most exposed area of the bones reached weathering stages 1 and 2, an intermediate progression between semi-arid tropical savannas, where weathering stages were initially described, and temperate and colder climates. By the final observation, the tibia of the horse, the heaviest taxon in our study, only has reached weathering stage 1, so our study agrees with previous studies in that the rate of weathering differs across body size, being slower in larger animals. The skull of Sus scrofa stands out for exhibiting modifications that differ from those observed in the tibias, probably due to the different structural anatomy of this bone. We have characterized the local meteorological conditions throughout the experiment and the soil composition as they might play a role in the weathering progression. This research constitutes a first attempt to calibrate the weathering scale in a Mediterranean climatic context, a setting that contains abundant and important fossil assemblages but that lacks bone weathering calibration.

Abstract Technological strategies for biface manufacture adopted during the Acheulean represent a significant shift in the Lower Palaeolithic. The appearance of intentional bifacial shaping indicates the imposition of form on stone tools not seen previously. Despite this importance, there is considerable scope for research into hominin decision-making while factoring in the differential properties of varied raw materials. Here, we discuss the results of an experimental knapping program of Acheulean handaxes on Naibor Soit quartzites (NSQ), aiming at investigating technological strategies observed at the Lower Floor TK Site (TKLF), Olduvai Gorge, Tanzania. We examine the unique properties of the NSQ raw material and the challenges faced during knapping slabs at various stages of the handaxe reduction sequence. We explore how the selection and extraction of suitable slabs for handaxe manufacture and the impact of specific geological structures within this raw material determine the final artefact form. We note the effect this had on the need for careful choices in selecting suitable slabs at the raw material sources based on considerations of the properties of the slab, thickness, and width, amongst other factors. Functional requirements and the NSQ slabs’ properties influenced strategies adopted for handaxe façonnage and the final tool morphology. We discuss choices made by Acheulean toolmakers when they adopted freehand and bipolar knapping techniques. These decisions can be identified through the nature of the debitage generated and the organization of flake scars on handaxes. We suggest that Acheulean hominins displayed high skill levels and evolved knapping strategies. These strategies allowed them to adapt to the complex task of implementing specific shaping techniques on NSQ slabs. This provides one of the few experimental studies that directly explore the impact of the particular requirements of flaking quartzites during the Acheulean. This study contributes to understanding the diversity of strategies and behavioral flexibility exhibited by Acheulean hominins. Highlights • Experimental knapping of handaxes on Naibor Soit quartzite (NSQ) slabs, Olduvai Gorge, Tanzania. • Reproduction of the reduction sequence used for handaxe façonnage on slabs at the Acheulean level of Lower Occupation Floor in Thiongo Korongo site (TKLF). • Investigating decision-making at various stages of the handaxe reduction sequence. • Issues related to the NSQ, leading to breakage and steps adopted by the knapper to control for the same. • Inferences on Acheulean technological abilities based on experimental studies and knapping decisions at stages in the reduction sequence.

Studying bone surface modifications (BSMs) in neotaphonomic research is an important aid to reconstruct agency in the archaeological and palaeontological record. The significance of correctly identifying BSMs has led to extensive debates about adequate methodological and interpretive frameworks to identify taphonomic agents and their bone-modifying patterns in dynamic taphonomic processes; especially those involving inter-agency interactions. Recent analytical innovations in the field have given rise to more updated and less biasing methods, including those rooted in multivariate statistics and artificial intelligence algorithms. Among the latter, convolutional neural networks have demonstrated a substantial potential in precision in the identification and characterization of BSMs. In this study, we present a successful application of these methods to reconstructing taphonomic agency in an archaeological context, specifically in Unit 2 of Tritons Cave (Lleida, Spain). Previous interpretations of this palaeontological layer suggested that it was a natural palimpsest created by carnivores, namely leopards. Through the present research, we objectively tested the original felid-accumulation hypothesis associated with the site’s original taphonomic analysis. Our findings provide additional evidence of the primary leopard agency in the formation of the assemblage and underscores the significant potential of transfer learning for identifying taxon-specific carnivore agency.

The major river basins of the Iberian Peninsula that drain towards the Atlantic coast contain extensive Lower Palaeolithic (Acheulean) records associated with well-preserved fluvial terrace sequences. These open-air archaeological records are often difficult to constrain chronologically due to a lack of suitable material for dating (e.g., faunal remains) or because their Middle Pleistocene antiquity precludes the use of otherwise routinely applicable geochronometric techniques such as conventional optically stimulated luminescence (OSL) dating. As a result, many important Iberian Acheulean sites lack precise and accurate chronologies, and their existing temporal frameworks are based solely on morphostratigraphic correlations with regional fluvial terrace systems. Here we present the first application of extended-range luminescence dating – namely multi-grain post-infrared infrared stimulated luminescence (pIR-IRSL) dating of K-feldspars and single-grain thermally transferred-OSL (TT-OSL) dating of quartz – to a series of terrace sequences in the Duero basin (central sector) and Guadiana basin, as well as associated Lower Palaeolithic sites of La Maya I, II and III along the Tormes River, Burganes (and related sites) along the Tera River, and Albalá along the Guadiana River. Additionally, we present results of a parallel electron spin resonance (ESR) quartz dating study of the Tormes River terrace (Duero basin), which has been undertaken independently on the same samples to enable stratigraphically paired dating comparisons. Our study indicates that sedimentary quartz from this sector of the Duero basin produces very weak TT-OSL signals, variable Al signal repeatability and below-average Ti signal fitting uncertainties, though it is still possible to determine consistent comparative ages using the measurements protocols employed here. For samples where both pIR-IRSL and TT-OSL signals were measured, the paired luminescence dating ages are in agreement at 1σ. Agreement between the quartz ESR and TT-OSL ages is also observed for one sample from the Tormes River. However, the ESR signals (both Al and Ti) of a second sample showed insufficient bleaching and age overestimation in comparison to the paired TT-OSL dataset. Comparison of our latest dating results with published chronological datasets point to some fluvial terraces of the Duero basin potentially having diachronous formation histories. Despite this, our combined chronological results show that the terrace systems are chronologically ordered and suggest that, regionally, the +8 to +34 m terraces likely post-date marine isotope stage (MIS) 10, whilst the +50 m terraces formed prior to, or during, MIS 10. The related Acheulean sites that contain lithic material in stratigraphic position are dated to MIS 9–7 (193–314 ka at 2σ age range), and temporally overlap with the early Middle Palaeolithic records in the Duero basin, also dated here to MIS 8–7 (or 159–259 ka at 2σ). Our results are consistent with previous observations regarding the chronological overlap of these two technologies in the region, and support the possibility of a non-linear pattern of replacement for the Acheulean in the Iberian Peninsula during the Lower to Middle Palaeolithic transition.

In Africa, the scarcity of hominin remains found in direct association with stone tools has hindered attempts to link Homo habilis and Homo erectus with particular lithic industries. The infant mandible discovered in level E at Garba IV (Melka Kunture) on the highlands of Ethiopia is critical to this issue due to its direct association with an Oldowan lithic industry. Here, we use synchrotron imaging to examine the internal morphology of the unerupted permanent dentition and confirm its identification as Homo erectus. Additionally, we utilize new palaeomagnetic ages to show that (i) the mandible in level E is ca. 2 million-years-old, and represents one of the earliest Homo erectus fossils, and (ii) that overlying level D, ca. 1.95 million-years-old, contains the earliest known Acheulean assemblage.

International audience

ABSTRACT Most biogeographers considered the Maghreb to be part of the Palearctic biogeographic region, though it is relatively recently that the proportion of Palearctic species increased there. How and when exactly these biogeographic changes occurred is not well understood, but they are probably the result of the increasing aridification of the Sahara and decreasing global temperatures. Fossils of Bos primigenius and Ceratotherium simum from a new fossil locality in a terrace of the Oued el Haï (NE Morocco) contribute to our understanding of some of these biogeographic processes and their timing. They also suggest an age between ~57 and ~100 ka for the terrace. The same evolutionary change in Bos in Europe and the Maghreb suggests geneflow as the most parsimonious explanation, though parallel evolution is an alternative possibility. Oued el Haï has the oldest well-documented record of C. simum in the Maghreb. The dispersal of this species to North Africa, where it replaced C. mauritanicum, may have occurred during a ‘Green Sahara Period’ between 80–85 or 100–105 ka, when the Maghreb had acquired already a Palearctic character. The study of the biogeography and requirements of the large mammals of the Maghreb may provide information to calibrate the region’s climate modelling.

Located within the Beni Fouda intramontane basin, the Oued Boucherit area (Guelta Zerga, North East Algeria) hosts a unique succession of archaeological and palaeontological deposits spanning from the late Pliocene to the Early Pleistocene. While the recent work by Sahnouni et al., (2018) mostly focused on the two Oldowan archaeological levels AB-Lw and AB-Up, we present here an updated overview of the entire Oued Boucherit sequence, resulting from a long-term multidisciplinary investigation that started in 1992. In particular, we report for the first time a description of the oldest palaeontological levels dated to >3 Ma, and of the uppermost archaeological level hosting Acheulean artefacts. The age-depth model initially proposed by Sahnouni et al. (2018) was further extended to chronologically constrain the whole sequence, which spans from ∼3.93 Ma at the bottom to ∼1.65 Ma at the top.The Oued Boucherit sedimentary sequence records the earliest evolutionary steps of lithic technology, with early Oldowan assemblages at Ain Boucherit dated to about 2.44 Ma (AB-Lw) and 1.92 Ma (AB-Up) Ma, followed by the ∼1.77-1.72 Ma assemblages of Ain Hanech and El Kherba showing more derived features, and the appearance of the Acheulean technology, dated to ∼1.67 Ma. This chonostratigraphic framework indicates that the Oued Boucherit area (<1 km2) hosts the oldest Oldowan and Acheulean assemblages identified so far in North Africa. It is also especially striking that their chronology is somewhat close to the earliest Oldowan and Acheulean evidence found in East Africa and South Africa.Moreover, at least six fossiliferous levels ranging from ∼3.78 to 1.77-1.72 Ma have been identified and stratigraphically positioned within the sequence. They represent a unique opportunity to study not only the evolution of large mammal faunal assemblages in North Africa, but may also give some key insights about the evolution of palaeoecological and palaeoenvironmental conditions in the region throughout the Late Pliocene to the Early Pleistocene. While the number of well-dated Plio-Quaternary faunal assemblages in North Africa remains somewhat limited, the Oued Boucherit sequence may be used as a reference for regional biochronological inferences.