The study of the radiocarbon age of bone bioapatite was initiated by necessity to date archaeological artifacts, which often contain little or no collagen as a result of poor preservation. Contamination of the organic fraction in the process of the burial or during museum preservation treatment generally prohibits the use of the collagen fraction for dating. Our investigation has shown that the pretreatment of bone with diluted acetic acid following a proscribed technique allows the separation of the bioapatite fraction from diagenetic carbonates. We have successfully used this technique to prepare and date samples of bone and of tooth enamel and dentin, with varying degrees of preservation condition, and from time intervals ranging from a few hundred ¹⁴C yr to greater than 40,000 ¹⁴C yr.

Isotopes are one of the best tools to reconstruct the paleoecology of extinct taxa, allowing us to evaluate their diet (through carbon; C3 and C4 plants), their niche breadth (BA) and the environment in which they lived. In the present work we go deeper in the use of isotopes, and explore a mathematical mixing model with the stable isotopic composition of one (carbon) and two elements (carbon and oxygen) to evaluate (i) the relative contributions of three types of food resources (leaves, fruits and C4 grass) for meso- and megaherbivores (body mass > 100 kg) that lived during the late Pleistocene in Sergipe, Brasil, and (ii) which of these herbivores (together with some faunivorous taxa) could be potential preys for Smilodon populator and Caiman latirostris. Finally, we reconstructed the paleoenvironment in which the vertebrate community of Sergipe lived and concluded that the environment of Sergipe was a closer and drier landscape than African savannah nowadays, at least between 27 ka to 11 ka. Keywords: Quaternary, mammals, paleoecology, South America, stable isotopes. Isotópos são uma das melhores ferramentas para reconstruir a Paleoecologia de táxons extintos, permitindo sugerir dieta (por meio do carbono, plantas C3 e C4), o nicho ecológico (BA) e ambiente em que viveram. No presente artigo nos aprofundamos no uso dos isotópos, e exploramos um modelo matemático misto com um isotópo (carbono) e dois isotópos (carbono e oxigênio) (i) para sugerir três recursos tipos de recursos alimentares (folhas, frutas e gramíneas C4) para meso-megaherbívoros (massa corporal acima de 100 kg) que viveram no Pleistoceno final de Sergipe, Brasil, e (ii) qual desses herbívoros (juntamente com faunívoros) foram presas potenciais de Smilodon populator e Caiman latirostris. Por fim, reconstruímos o paleoambiente na qual a comunidade de vertebrados de Sergipe viveu, concluindo que eramais fechada e seca do que as savanas da Africa atualmente, pelo menos entre 27 mil a 11 mil anos atrás. Palavras-chave: Quaternário, paleoecologia, América do Sul, isotópos estáveis. Isotopes are one of the best tools to reconstruct the paleoecology of extinct taxa, allowing us to evaluate their diet (through carbon; C3 and C4 plants), their niche breadth (BA) and the environment in which they lived. In the present work we go deeper in the use of isotopes, and explore a mathematical mixing model with the stable isotopic composition of one (carbon) and two elements (carbon and oxygen) to evaluate (i) the relative contributions of three types of food resources (leaves, fruits and C4 grass) for meso- and megaherbivores (body mass > 100 kg) that lived during the late Pleistocene in Sergipe, Brasil, and (ii) which of these herbivores (together with some faunivorous taxa) could be potential preys for Smilodon populator and Caiman latirostris. Finally, we reconstructed the paleoenvironment in which the vertebrate community of Sergipe lived and concluded that the environment of Sergipe was a closer and drier landscape than African savannah nowadays, at least between 27 ka to 11 ka. Keywords: Quaternary, mammals, paleoecology, South America, stable isotopes. Isotópos são uma das melhores ferramentas para reconstruir a Paleoecologia de táxons extintos, permitindo sugerir dieta (por meio do carbono, plantas C3 e C4), o nicho ecológico (BA) e ambiente em que viveram. No presente artigo nos aprofundamos no uso dos isotópos, e exploramos um modelo matemático misto com um isotópo (carbono) e dois isotópos (carbono e oxigênio) (i) para sugerir três recursos tipos de recursos alimentares (folhas, frutas e gramíneas C4) para meso-megaherbívoros (massa corporal acima de 100 kg) que viveram no Pleistoceno final de Sergipe, Brasil, e (ii) qual desses herbívoros (juntamente com faunívoros) foram presas potenciais de Smilodon populator e Caiman latirostris. Por fim, reconstruímos o paleoambiente na qual a comunidade de vertebrados de Sergipe viveu, concluindo que eramais fechada e seca do que as savanas da Africa atualmente, pelo menos entre 27 mil a 11 mil anos atrás. Palavras-chave: Quaternário, paleoecologia, América do Sul, isotópos estáveis. Isotopes are one of the best tools to reconstruct the paleoecology of extinct taxa, allowing us to evaluate their diet (through carbon; C3 and C4 plants), their niche breadth (BA) and the environment in which they lived. In the present work we go deeper in the use of isotopes, and explore a mathematical mixing model with the stable isotopic composition of one (carbon) and two elements (carbon and oxygen) to evaluate (i) the relative contributions of three types of food resources (leaves, fruits and C4 grass) for meso- and megaherbivores (body mass > 100 kg) that lived during the late Pleistocene in Sergipe, Brasil, and (ii) which of these herbivores (together with some faunivorous taxa) could be potential preys for Smilodon populator and Caiman latirostris. Finally, we reconstructed the paleoenvironment in which the vertebrate community of Sergipe lived and concluded that the environment of Sergipe was a closer and drier landscape than African savannah nowadays, at least between 27 ka to 11 ka. Keywords: Quaternary, mammals, paleoecology, South America, stable isotopes. Isotópos são uma das melhores ferramentas para reconstruir a Paleoecologia de táxons extintos, permitindo sugerir dieta (por meio do carbono, plantas C3 e C4), o nicho ecológico (BA) e ambiente em que viveram. No presente artigo nos aprofundamos no uso dos isotópos, e exploramos um modelo matemático misto com um isotópo (carbono) e dois isotópos (carbono e oxigênio) (i) para sugerir três recursos tipos de recursos alimentares (folhas, frutas e gramíneas C4) para...

The radiocarbon (¹⁴C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties.

An assemblage of coatings in cryoaridic soils (Skeletic Cambisols Protocalcic) of southwestern Tyva is considered as a key block of soil memory, which is an intrasoil archive of landscape and climate changes in regional geosystems in the Holocene. The results of hierarchical macro-, meso-, and micromorphological studies of a large assemblage of coatings and the data on the X-ray microanalysis of coatings and composition of stable carbon and oxygen isotopes, as well as on radiocarbon dating of coatings are presented. The synthesis of the results made it possible to reconstruct the main evolutionary phases of cryoaridic soils in the Holocene and landscape and climate changes that induced their alteration. The following climatogenic evolutionary phases of pedogenesis were distinguished: (1) formation of microsparite–micritic dense silica-containing coatings due to short-term fluctuations of the shallow alkaline bicarbonate groundwater level in the semiarid–arid climate; (2) formation of sparitic dense coatings under the slow accumulation of carbonates from low-mineralized bicarbonate water at the higher lake level as compared to the present one in the less arid conditions; (3) the eluvial-illuvial formation of micritic loose coatings under stable automorphic semiarid conditions; (4) formation of Fe-humus coatings in cool humid climate (Al–Fe-humus phase of pedogenesis); (5) the recommencement of the eluvial-illuvial formation of micritic loose coatings under aridization of the last thousand years of the Holocene.

Caves and rockshelters are critical loci for the analysis and understanding of human trajectories in the past. Use and re-uses of the same context, however, might have had serious impacts on depositional aspects. This is particularly true for the archaeological history of desert environments, such as the central Sahara, where most of the deposits are made of loose sand, rich in organic matter. Besides traditional stratigraphic reconstructions and a detailed study of the material culture, radiocarbon measurements from different contexts analyzing several types of material (bone, dried and charred coprolite, uncharred and charred plant remains, etc.) can highlight intrinsic critical aspects of ¹⁴C determinations. These measurements must be carefully evaluated to provide a correct chronological assessment of the life history of the site. We present the statistics derived from the set of about 50 ¹⁴C measurements from the site of Takarkori, southwest Libya, where early Holocene foragers and then groups of cattle herders inhabited the area from ∼10,200 to 4600 cal yr BP. We have used the BCal Bayesian ¹⁴C calibration program designed for statistical presentation of the calibrated data and the estimation of their probability for different phases. Results indicate that the Takarkori rockshelter was occupied during 4 phases of the following cultures: Late Acacus from 10,170 to 8180 cal yr BP; Early Pastoral, 8180–6890 cal yr BP; Middle Pastoral, 7160–5610 cal yr BP; and Late Pastoral, 5700–4650 cal yr BP.

The timing for the evolution of the capacity to inscribe the landscape with rock art has global relevance. While this was an in-built capacity when Homo sapiens first colonized the Americas, the heterogeneous distribution of rock art shows that it was a facultative behavior arising under unknown socioecological conditions. Patagonia was the last region to be explored by humans. While its rock art is globally important, it remains largely undated by absolute methods. We report the earliest set of directly radiocarbon-dated rock art motifs from the archaeological site Cueva Huenul 1 (northwestern Patagonia, Argentina), starting at 8.2 thousand years before the present (ka B.P.), predating previous records by several millennia, and encompassing over 3 ka (~130 human generations). This mid-Holocene “rock art emergence” phase overlaps with extremely arid conditions and a human demographic stasis. We suggest that this diachronic rock art emerged as part of a resilient response to ecological stress by highly mobile and low-density populations.