Chronometric Data Research Articles

Chronometric data and stratigraphic evidence support discontinuity between Neanderthals and early Homo sapiens in the Italian Peninsula

The process by which Palaeolithic Europe was transformed from a Neanderthal-dominated region to one occupied exclusively by Homo sapiens has proven challenging to diagnose. A blurred chronology has made it difficult to determine when Neanderthals disappeared and whether modern humans overlapped with them. Italy is a crucial region because here we can identify not only Late Mousterian industries, assumed to be associated with Neanderthals, but also early Upper Palaeolithic industries linked with the appearance of early H. sapiens, such as the Uluzzian and the Aurignacian. Here, we present a chronometric dataset of 105 new determinations (74 radiocarbon and 31 luminescence ages) from four key southern Italian sites: Cavallo, Castelcivita, Cala, and Oscurusciuto. We built Bayesian-based chronometric models incorporating these results alongside the relative stratigraphic sequences at each site. The results suggest; 1) that the disappearance of Neanderthals probably pre-dated the appearance of early modern humans in the region and; 2) that there was a partial overlap in the chronology of the Uluzzian and Protoaurignacian, suggesting that these industries may have been produced by different human groups in Europe.

Late time cosmic acceleration through parametrization of Hubble parameter in [formula omitted] gravity

This paper explores the rapid expansion of the Universe during its later stages within the context of f(R,Lm) gravity theory. We present a novel parametrization of the Hubble parameter in a manner independent of any specific model and employ it to analyze the Friedmann equations within the FLRW Universe framework. Using a Markov Chain Monte Carlo (MCMC) approach, we derive the model parameters by analyzing a composite dataset comprising 31 Cosmic Chronometers (CC) data points, 26 independent Baryonic Acoustic Oscillations (BAO) measurements, and 1701 data points from Pantheon+SH0ES dataset. The trajectory of the deceleration parameter highlights the shift from deceleration to acceleration in the evolution of the Universe. Additionally, we delve into the dynamics of fundamental cosmological variables for two nonlinear f(R,Lm) models, including energy density, pressure, equation of state (EoS) parameter, and energy conditions.

Terrace formation linked to outburst floods at the Diexi palaeo-landslide dam, upper Minjiang River, eastern Tibetan Plateau

Abstract. River terraces are frequently investigated with the aim of extracting information regarding tectonic or climate forcing on the evolution of landscapes. Terraces formed following the blockage of valleys by large-scale landsliding have received limited attention despite the high likelihood of their prevalence in landslide-dominated mountain belts. Here, we investigate the geomorphology, sedimentology, and chronology of two outstanding sets of terraces upstream of the giant river-blocking Diexi palaeo-landslide on the upper Minjiang River, eastern Tibetan Plateau. The first set occurs at Tuanjie village and has seven levels (T1–T7); the second set, at Taiping village, has three levels (T1–T3). All the terraces display a consistent sedimentary sequence comprising lacustrine muds topped by fluvial gravel sometimes capped by loess and a palaeosol. Based on field examination, lithofacies analysis, elevation data, and chronometric data (optically stimulated luminescence and radiocarbon dating), we correlate T1, T2, and T3 at Taiping with T5, T6, and T7 at Tuanjie. Our analysis suggests that two damming and three outburst events have occurred at the Diexi palaeo-landslide over the past 35 000 years. A giant landslide (> 300 m high) blocked the river before 35 ka, followed by the first outburst flood at ∼ 27 ka; the river was blocked again between 27 and 17 ka, followed by a second outburst at ∼ 17 ka. A third outburst at ∼ 12 ka was followed by gradual fluvial incision of the palaeo-dam crest to its current level. We attribute the terraces at Diexi to the recurrent blockage and outburst events, which reflect the shifting sediment transport capacity and incision at the palaeo-dam crest. Here, climatic fluctuations play a minor role in terrace formation, and tectonism plays no role at all.

Baring Bearma’s Bounty. Human and animal signatures in the Quaternary contexts of the Bearma Valley, Central India

The rich Palaeolithic and fossil records of the Narmada and Son Valleys dominate paleoanthropological research from Central India, in large part because of their well-preserved Quaternary deposits. While data from other river valleys is emerging, finding both lithics and fauna in close proximity remains rare and spatio-temporal inconsistencies make assessment of implications for the larger area challenging. Ongoing investigations along the Bearma, the largest tributary of the River Sonar, has yielded a low-density fossil assemblage across three localities and a proximally located Large Flake Acheulean (LFA) site. The small fossil assemblage currently consists of both cranial and post-cranial elements in differing states of completeness and preservation, likely a function of post-depositional impacts and the time elapsed since exposure. Many of the important large mammalian herbivore species belonging to bovid, equid, cervid and proboscidean taxa that are commonly found during the Late Quaternary of the Indian Subcontinent are represented, making the region worthy of comparison with neighbouring fossiliferous areas. The new Palaeolithic site encountered less than 500 m downstream from the fossil localities is almost exclusively LFA technology in nature made primarily on slabs of Vindhyan sandstone. Preliminary analysis of the collected artefacts indicates a focus on the production of large flake blanks and debitage products from large cores configured according to various unifacial and bifacial technological methods. The frequency of these elements suggests the use of the area as a factory site, while the unmistakable presence of bifaces and other tools warrant broader interpretations. With the current lack of stratigraphic and chronometric data on either assemblage, it is premature to draw any chrono-contextual associations between the fossils and artefacts. However, this ∼5 km stretch of the Bearma yielding two significant proxies presents an excellent opportunity to understand hominin behaviour during the Quaternary and fill both geographical and temporal gaps in Central India.

Quintessential f(G) gravity with statistically fitting of H(z)

Inspired by high-energy physics and by considering standard gravity theory as the low-energy limit of quantum theory, the modification of general relativity as [Formula: see text] has been proposed. This paper is dedicated to investigating the cosmological model of modified Gauss–Bonnet gravity in four dimensions. General field equations for the four-dimensional Friedmann– Robertson–Walker metric are given in detail. Also, it is well known that Hubble parameter [Formula: see text] measurements are helpful for the inference of cosmological model parameters. We try to explain the MCMC statistical approach used to calculate Hubble’s parameter. The resulting form of [Formula: see text] was limited using Cosmic Chronometric data, Standard Candles SN Ia from Pantheon, and Baryon Acoustic Oscillations to obtain the best match values by using the regression equation. Finally, to examine the late-time dynamics of our Universe, the behavior of physical and kinematic variables like the deceleration parameter [Formula: see text], State-finder parameters [Formula: see text], diagnostic parameter ([Formula: see text]), equation of state parameter as well as the behavior of energy conditions versus redshift with the parameter values are presented.

Study of pressure parametric dark energy model in the framework of f(Q) gravity

In this work, we have proposed a simple parametrization for the pressure component [Formula: see text] of the dark energy model and have studied the cosmological implications of this model in the framework of [Formula: see text] modified gravity theory, aka, the symmetric teleparallel gravity theory, where Q is known as the nonmetricity scalar. By considering a particular parametric form of [Formula: see text], we obtained the Hubble solution for the [Formula: see text] modified gravity model. In order to see whether this model is consistent with or challenges the [Formula: see text]CDM limits, we tried to put constraints on the model parameters using the recent observational datasets like Hubble data, Cosmic Chronometer data, Type Ia Supernovae (SNIa) data, baryonic acoustic oscillations (BAO) data. We have employed the [Formula: see text] minimization technique and have carried out the Markov Chain Monte Carlo (MCMC) analysis using emcee package. We have found that the deceleration parameter shows a smooth transition from positive to negative value in recent past which is essential for the structure formation of the Universe. It has been found that the parametric form of the dark energy pressure parameter is consistent with current cosmological scenario.

Reconstruction of symmetric teleparallel gravity with energy conditions

This research investigates the impact of modified gravity on cosmic scales, focusing on [Formula: see text] cosmology. By applying energy conditions, the study reconstructs various [Formula: see text] models, considering an accelerating Universe, quintessence, and a cosmological constant [Formula: see text]. Using up-to-date observational data, including the Supernova Pantheon sample and cosmic chronometer data, Hubble constants [Formula: see text] are estimated as [Formula: see text] km/s/Mpc (from [Formula: see text] data) and [Formula: see text] km/s/Mpc (from pantheon compilation of SN Ia data). The matter energy density parameter ([Formula: see text]) is calculated as [Formula: see text] (OHD) and [Formula: see text] (SN Ia). Furthermore, as a function of red-shift [Formula: see text], explicit expressions of [Formula: see text] and the EOS parameter [Formula: see text] are produced, and their graphical analysis describes the late time acceleration of the Universe without the usage of dark energy.

Neanderthal resilience and adaptability: insights from the Abric Pizarro faunal assemblage during the MIS 4

The examination of faunal assemblages through zooarchaeological analyses constitutes a fundamental approach for gaining insight into the intricate behaviours of Neanderthals. Previous investigations have primarily focused on periods of relative environmental stability, and this has provided a wealth of relevant archaeological data. However, our understanding of Neanderthal resilience during the MIS 4, a period presumably characterised by harsh environmental conditions, remains limited. This study presents the first comprehensive analysis of the faunal assemblages from Levels M and P at Abric Pizarro. The geographic location of Abric Pizarro in the southeast Pre-Pyrenees, combined with chronometric dating, offers a unique opportunity to explore Neanderthal behaviours during a poorly known chronological period. The detailed zooarchaeological analysis comprised taxonomic identification, taphonomic analysis and age-at-death profiling to explore the adaptability and flexibility in the Neanderthal diet. The findings indicate that Neanderthal groups incorporated a diverse range of protein resources from small herbivores (e.g., caprids) to very large herbivores (e.g., Bos/Bison). These results not only demonstrate an adaptability to changing environments in an area traditionally deemed unsuitable for long-term occupation, but also contributes significantly to our understanding of the complex behaviours exhibited by Neanderthals.

The state of the dark energy equation of state circa 2023

We critically examine the state of current constraints on the dark energy (DE) equation of state (EoS) w. Our study is motivated by the observation that, while broadly consistent with the cosmological constant value w = -1, several independent probes appear to point towards a slightly phantom EoS (w ∼ -1.03) which, if confirmed, could have important implications for the Hubble tension. We pay attention to the apparent preference for phantom DE from Planck Cosmic Microwave Background (CMB) data alone, whose origin we study in detail and attribute to a wide range of (physical and geometrical) effects. We deem the combination of Planck CMB, Baryon Acoustic Oscillations, Type Ia Supernovae, and Cosmic Chronometers data to be particularly trustworthy, inferring from this final consensus dataset w = -1.013+0.038 -0.043, in excellent agreement with the cosmological constant value. Overall, despite a few scattered hints, we find no compelling evidence forcing us away from the cosmological constant (yet).

What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem

Modern cosmology presents important challenges such as the Hubble Tension, El Gordo’s collision, or the impossible galaxies (z > 10). Slight modifications to the standard model propose new parameters (e.g., the early and dynamical dark energy). On the other hand, alternatives such as the coasting universes (e.g., the hyperconical model and the spatially flat R h = ct universe) are statistically compatible with most of the observational tests, but still present theoretical problems in matching the observed matter contents since they predict a “zero active gravitational mass.” To solve these open issues, we suggest that general relativity might be not valid at cosmic scales, but it would be valid at local scales. This proposal is addressed from two main features of the embedding hyperconical model: (1) the background metric would be independent of the matter content, and (2) the observed cosmic acceleration would be fictitious and because of a distorted stereographic projection of coordinates that produce an apparent radial inhomogeneity from homogeneous manifolds. Finally, to support the discussion, standard observational tests were updated here, showing that the hyperconical model is adequately fitted to Type Ia supernovae, quasars, galaxy clusters, baryon acoustic oscillations, and cosmic chronometer data sets.

New Late Pleistocene age for the Homo sapiens skeleton from Liujiang southern China

The emergence of Homo sapiens in Eastern Asia is a topic of significant research interest. However, well-preserved human fossils in secure, dateable contexts in this region are extremely rare, and often the subject of intense debate owing to stratigraphic and geochronological problems. Tongtianyan cave, in Liujiang District of Liuzhou City, southern China is one of the most important fossils finds of H. sapiens, though its age has been debated, with chronometric dates ranging from the late Middle Pleistocene to the early Late Pleistocene. Here we provide new age estimates and revised provenience information for the Liujiang human fossils, which represent one of the most complete fossil skeletons of H. sapiens in China. U-series dating on the human fossils and radiocarbon and optically stimulated luminescence dating on the fossil-bearing sediments provided ages ranging from ~33,000 to 23,000 years ago (ka). The revised age estimates correspond with the dates of other human fossils in northern China, at Tianyuan Cave (~40.8–38.1 ka) and Zhoukoudian Upper Cave (39.0–36.3 ka), indicating the geographically widespread presence of H. sapiens across Eastern Asia in the Late Pleistocene, which is significant for better understanding human dispersals and adaptations in the region.

Observational constraints for cubic gravity theory based on third order contractions of the Riemann tensor

The paper studies different observational features in the case of a specific cubic gravity theory, based on third order contractions of the Riemann tensor. Considering viable cosmic chronometers data, baryon acoustic oscillations, and supernovae, we analyze the viability of such a theoretical model, obtaining specific constraints for different parameters in the current scenario. It is shown that the present extension of the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document}CDM cosmological model is compatible with recent data sets. The results indicate that the dark energy equation of state is exhibiting a phantom regime in the near past in the case of the best fitted values, a behavior which is in agreement with various phenomenological studies.

Beyond [formula omitted]CDM with [formula omitted]CDM: Criticalities and solutions of Padé Cosmography

Recently, cosmography emerged as a valuable tool to effectively describe the vast amount of astrophysical observations without relying on a specific cosmological model. Its model-independent nature ensures a faithful representation of data, free from theoretical biases. Indeed, the commonly assumed fiducial model, the ΛCDM, shows some shortcomings and tensions between data at late and early times that need to be further investigated. In this paper, we explore an extension of the standard cosmological model by adopting the f(z)CDM approach, where f(z) represents the cosmographic series characterizing the evolution of recent universe driven by dark energy. To construct f(z), we take into account the Padé series, since this rational polynomial approximation offers a better convergence at high redshifts than the standard Taylor series expansion. Several orders of such an approximant have been proposed in previous works, here we want to answer the questions: What is the impact of the cosmographic series choice on the parameter constraints? Which series is the best for the analysis? So, we analyze the most promising ones by identifying which order is preferred in terms of stability and goodness of fit. Theoretical predictions of the f(z)CDM model are obtained by the Boltzmann solver code and the posterior distributions of the cosmological and cosmographic parameters are constrained by a Monte Carlo Markov Chains analysis. We consider a joint data set of cosmic microwave background temperature measurements from the Planck collaboration, type Ia supernovae data from the latest Pantheon+ sample, baryonic acoustic oscillations and cosmic chronometers data. In conclusions, we state which series can be used when only late time data are used, while which orders has to be considered in order to achieve the necessary stability when large redshifts are considered.

Managing precision: how to use chronometers accurately at sea

ABSTRACT Marine chronometers, often considered precision instruments, proliferated in navigational practices during the nineteenth century. This paper examines their use in the hands of naval officers in the early-nineteenth century. It argues that both the instruments and their operators required careful management and regulation. In addition, officers learnt and adapted observatory practices relating to the process of data collection and management. Through these means, chronometric data was collected, organized, and reduced to negotiate accurate results.

Cosmological constraints on Λ(t)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda (t)$$\\end{document}CDM models

Problems with the concordance cosmology Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document}CDM as the cosmological constant problem, coincidence problems and Hubble tension has led to many proposed alternatives, as the Λ(t)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda (t)$$\\end{document}CDM, where the now called Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document} cosmological term is allowed to vary due to an interaction with pressureless matter. Here, we analyze one class of these proposals, namely, Λ=α′a-2+βH2+λ∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda =\\alpha 'a^{-2}+\\beta H^2+\\lambda _*$$\\end{document}, based on dimensional arguments. Using SNe Ia, cosmic chronometers data plus constraints on H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} from SH0ES and Planck satellite, we constrain the free parameters of this class of models. By using the Planck prior over H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document}, we conclude that the λ∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _*$$\\end{document} term can not be discarded by this analysis, thereby disfavouring models only with the time-variable terms. The SH0ES prior over H0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_0$$\\end{document} has an weak evidence in this direction. The subclasses of models with α′=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha '=0$$\\end{document} and with β=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta =0$$\\end{document} can not be discarded by this analysis. Finally, by using distance priors from CMB, the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document} time-dependence was quite restricted.

Revisiting [formula omitted] cosmologies

We review the status of f(R,T) cosmological models, where T is the trace of the energy momentum tensor Tμν. We start focusing on the modified Friedmann equations for the minimally coupled gravitational Lagrangian of the type f(R,T)=R+αeβT+γnTn. We show that in such a minimally coupled case there exists a useful constraining relation between the effective fractionary total matter density with an arbitrary equation of state parameter and the modified gravity parameters. With this association the modified gravity sector can be independently constrained using estimations of the gas mass fraction in galaxy clusters. Using cosmological background cosmic chronometers data and demanding the universe is old enough to accommodate the existence of Galactic globular clusters with ages of at least ∼14 Gyrs we find a narrow range of the modified gravity free parameter space in which this class of theories remains viable for the late time cosmological evolution. This preferred parameter space region accommodates the ΛCDM limit of f(R,T) models. We also work out the non-minimally coupled case in the metric-affine formalism and find that there are no viable cosmologies in the latter situation. However, when analyzing the cosmological dynamics including a radiation component, we find that this energy density interacts with the matter field and it does not scale according to the typical behavior. We conclude stating that f(R,T) gravity is not able to provide a full cosmological scenario and should be ruled out as a modified gravity alternative to the dark energy phenomena.

Evolution of the “ancient Kedah”: A study on urban forms at Sungai Batu Archaeological Complex (SBAC), Bujang Valley, Kedah, Malaysia

Archaeological research at the Sungai Batu Archaeological Complex (SBAC), which has been carried out until 2023, aims to complete the chronological data and urbanization process of the ancient Kedah. This study will especially prove that the ongoing urbanization process is aimed at developing the iron smelting industry and trade in ancient Kedah, especially in SBAC. This is because archaeological research at SBAC has proven that with the existence of the ancient Kedah iron smelting workshop at SBAC, river jetties, port management, rituals, and Buddhist monuments began to be erected, all of which can be determined by chronometric dating. The results of the chronometric dating have proven that the ancient Kedah Kingdom existed since the 6th century BC and was oriented towards the trade of iron resources, which allowed the use of the area to grow rapidly. The process of urbanization and land use clearly conforms to Lynch's principle, which emphasizes the principles of 1) paths, 2) edges, 3) districts, 4) nodes, and 5) landmarks in the development process of land use and urbanization in the complex.

Probing accelerating cosmos via reconstructed Hubble parameter and its influence on f(T) gravity models

This article introduces a new way of studying the accelerating cosmos without relying on specific models. It proposes a new parametric form of the Hubble parameter (HP) and uses a Markov Chain Monte Carlo (MCMC) approach to determine the model parameters. The analysis incorporates a comprehensive dataset consisting of 34 cosmic chronometers (CC) data points, 40 non-correlated baryonic acoustic oscillations (BAO) points, and 1701 updated Pantheon+ supernovae type Ia (SNeIa) data points. The study investigates various aspects of the model's behavior, such as the transition from deceleration to acceleration, and the evolution of jerk and snap parameters. Constraints are applied to the model parameters as well as the Hubble constant (H0). Additionally, the parameter values obtained are used to study f(T) gravity models and compare them with observational data. This research provides valuable insights into the nature of the accelerating Universe and highlights the importance of using a parametrized approach in cosmological studies.

Early North African Acheulean techno-economic systems at Thomas Quarry I - L1 (Casablanca, Morocco).

North Africa is a key area for understanding cultural processes that led to the Acheulean pan - African emergence and expressions and the related hominin population dynamics. Unfortunately, little is known about the early Acheulean in this vast area of the African continent due to the scarceness of archaeological sites in stratigraphic context with reliable chronometric data, human remains, and technological analyses of the lithic industries. Here, we present the first comprehensive techno-economic analysis of the early Acheulean assemblage from Thomas Quarry I - Unit L1 (ThI-L1, Casablanca, Morocco), which is the earliest Acheulean site of North Africa, unambiguously dated to 1.3 Ma. Fieldwork has unearthed faunal remains and a lithic collection containing over 3800 artefacts, which represents one of the largest series for the early African Acheulean. The assemblage is mainly composed of quartzites and to a lesser extent of silicites, both abundantly available near the site. Previously published results of the silicite study revealed two different productions for the extraction of small flakes and of bladelet-like flakes. In this work, we analyse the techno-economic systems of the quartzite assemblage. Two distinct quartzite productions co-occur, one devoted to the manufacture of Large Cutting Tools (LCTs), the other focused on the extraction of small-medium sized flakes. LCTs were usually produced from large cobbles, less often from large flakes detached mainly using the entame core method. The main technical objective was to obtain large pointed tools and, more rarely, large tools with a transversal cutting edge. Results support the existence of a strong synergy between conceptual and operational schemes regulated by the ability to anticipate the final tool morphology and to apply standardized shaping procedures to manufacture recurrent morphotypes. Quartzite small-medium sized flakes were produced by a diversity of flaking methods adapted to the cobble blank morphologies and were not retouched. The results allow to assess that the earliest technical expression of the Acheulean in North Africa is characterised by a high diversification of the stone knapping outcomes, the complexity of the mental templates, and the flexible structure of the operational schemes.

An Annotated Compilation of Chronometric Dates for the Middle-Upper Palaeolithic Transition (45-30 ka BP) in Northern Iberia (Spain)

An Annotated Compilation of Chronometric Dates for the Middle-Upper Palaeolithic Transition (45-30 ka BP) in Northern Iberia (Spain)