Research by the Tlalancaleca Archaeological Project (PATP) has corroborated modifications to the Middle Formative chronology in Puebla-Tlaxcala (Lesure et al. 2006, 2014) using Bayesian modeling on 26 radiocarbon dates from Tlalancaleca. The present study is the first to evaluate the region’s Middle Formative chronology with radiocarbon dates from superposed stratigraphy. Nine Bayesian models were constructed with different combinations of radiocarbon dates and OxCal’s phase and sequence functions to determine the beginning and end of the Texoloc phase. Results place the Tlatempa-Texoloc transition at around 650 cal BC and the Texoloc-Tezoquipan transition at around 500 cal BC. The OxCal Interval function supports a timespan of approximately 150 years for the duration of the Texoloc phase. These results suggest the process of initial urbanization in Central Mexico was a rapid one.

The recovery of nearly 250 burials at the El Olivar site provided the opportunity to address questions regarding the groups inhabited coastal settings of the semiarid north of Chile between the 800 and 1540 AD. Stable isotopes of carbon, nitrogen, and oxygen were analyzed from 60 human samples. Radiocarbon (14C) analyses were conducted in 20 samples from camelids and 42 human samples. Subsequently, a sample of 25 individuals exhibiting diagnostic cultural features of the Las Ánimas Cultural Complex (LACC) and the Chilean Diaguita Culture (CDC) was selected for the purpose of assessing differences in their diet and mobility and clarifying their chronology. The δ13C and δ15N values obtained revealed the existence of a small group of individuals (n=6) with a diet based on C3 plants and terrestrial protein, and another major group (n=33) with values compatible with the consumption of C4 plants and marine resources. Four of the six individuals of the small group presented Ánimas diagnostic features, and in the major group were identified both Ánimas and Diaguita individuals. The δ18O values exhibited a similarity between the Ánimas and Diaguita individuals, suggesting coastal-to-inland mobility in both groups. Calibrated 14C dates indicate that El Olivar was occupied for a period of nearly 380 years, spanning between 1150 and 1536 AD, and that between the 1300 and 1400 AD, Ánimas and Diaguita individuals coexisted at El Olivar. These findings call into question the current thought that the CDC emerged from the LACC around 1000 AD, and that both represent different archaeological entities.

Radiocarbon (14C) measurements on dissolved inorganic carbon (DIC) are a powerful tool to trace water masses and carbon cycling in the ocean. Existing methodologies to determine the 14C content of seawater DIC requires large volumes of sample (usually >100 mL) and specialized graphitization techniques to achieve the accuracy and precision needed for meaningful data interpretation. The advancement of the CO2 gas ionization accelerator mass spectrometry (AMS) technique today allows routine 14C measurements on small samples (<100 µgC) and may thus permit reducing the sample volumes needed to determine 14C content of seawater DIC to ∼2 mL. The proposed method utilizes the carbonate handling system (CHS), gas interface system (GIS) and MICADAS AMS, and provides good accuracy but reduced precision compared to established methods. Good accuracy is shown by comparing results for a marine in-house DIC standard and a DIC seawater profile from Antarctica between the proposed CHS-GIS-MICADAS approach and reference measurements conducted on the same material at established laboratories (ETH and NOSAMS). Further, two sedimentary porewater profiles from a fjord system in Svalbard are presented. Despite good agreement, the precision of the CHS-GIS-MICADAS approach is reduced, potentially limiting possible interpretations on seawater DIC. Nonetheless, the reduction of sample volumes proves particularly helpful to analyze porewater DIC from sediment cores, where sample material is notoriously limited, reduces the required amounts of toxic HgCl2 and simplifies expedition logistics.

By constraining organic carbon (OC) turnover times and ages, radiocarbon (14C) analysis has become a crucial tool to study the global carbon cycle. However, commonly used “bulk” measurements yield average turnover times, masking age variability within complex OC mixtures. One method to unravel intra-sample age distributions is ramped oxidation, in which OC is oxidized with the aid of oxygen at increasing temperatures. The resulting CO2 is collected over prescribed temperature ranges (thermal fractions) and analyzed for 14C content by accelerator mass spectrometry (AMS). However, all ramped oxidation instruments developed to date are operated in an “offline” configuration and require several manual preparation steps, hindering sample throughput and reproducibility. Here we describe a compact, online ramped oxidation (ORO) setup, where CO2 fractions are directly collected and transferred for 14C content measurement using an AMS equipped with a gas ion source. Our setup comprises two modules: (i) an ORO unit containing two sequential furnaces, the first of which holds the sample and is ramped from room temperature to ∼900°C, the second of which is maintained at 900°C and holds catalysts (copper oxide and silver) to ensure complete oxidation of evolved products to CO2; and (ii) a dual-trap interface (DTI) collection unit containing two parallel molecular sieve traps, which alternately collect CO2 from a given fraction and handle its direct injection into the AMS. Initial results for well-characterized samples indicate that 14C content uncertainties and blank background values are like those obtained during routine gas measurements at ETH, demonstrating the utility of the ORO-DTI setup.

Understanding the developmental and occupational histories of Ancestral Maya settlements is crucial for interpreting their roles in broader social, political, and economic dynamics. This article presents 62 new accelerator mass spectrometry (AMS) 14C dates from residential groups in the outlying settlement zone at Alabama, a major inland Ancestral Maya center in East-Central Belize. Alabama is a rare example of a “boomtown” in the Maya lowlands, experiencing rapid development primarily during the 8th and 9th century CE, corresponding to the Late to Terminal Classic periods. Using Bayesian stratigraphic sequence models, we construct detailed developmental and occupational histories for the townsite, clarifying the timing of its development, occupation, and abandonment. Our analysis reveals complex residential histories, confirming a rapid tempo of Late and Terminal Classic settlement growth and indicating continuities in occupation into the 10th century CE and beyond. Furthermore, we identify two separate periods of occupation during the Early Classic (cal AD 345–545) and the Late Postclassic (cal AD 1325–1475), demonstrating that parts of the settlement were inhabited at different intervals over many centuries. These results offer the first detailed deep-history perspective for the East-Central Belize region, establishing a framework that addresses challenges in chronology-building posed by poor pottery preservation and the complexities of earthen-core architecture at the site and enabling future chronological modeling in this lesser-known frontier of the eastern Maya lowlands.

Radiocarbon (14C) dating of soil samples by accelerator mass spectrometry (AMS) has been proven useful for studying carbon (C) cycling in terrestrial ecosystems. However, this application has two primary difficulties in sample preparation: inhibition of graphite formation due to sulfur (S)-containing impurities and contamination of samples with modern C (MC). Herein, we evaluated these effects using three sample preparation methods (silver foil, silver wire, and Sulfix) by conducting AMS-14C measurements of a 14C-dead charred wood and S-rich soil samples. The preparation methods were all successful in graphite formation and AMS-14C measurement for soil samples with an organic S content <6.9 wt%. The methods showed different percent modern carbon (pMC) values from 0.16% to 0.64% for the 14C-dead sample. The results also revealed that across different methods, MC contamination can be significantly reduced by applying two-step procedure (combustion and subsequent reaction to remove S-containing impurities) during sample preparation. The three methods had a negligible influence on determining the 14C age for samples that were at least younger than 12,000 yr BP. As the 14C ages of the soil samples are typically younger than 12,000 yr BP, any method explored in this study can be employed for 14C dating with sufficient accuracy for application to C cycle studies.

Most of the carbonate samples have a basic well-defined pretreatment protocol for 14C-AMS dating, but particularities of specific organisms have to be treated with care. This is the case of stromatolite samples, in which carbonate is formed by biogenesis and also has a porous structure that could contain recent organic material as a contaminant. In this work, we analyzed the differences in the radiocarbon content by using organic matter removals before chemical treatment with HCl: sodium hypochlorite (NaOCl) a 0.7M solution with pH ∼11, and hydrogen peroxide (H2O2) an 8.8M solution with pH ∼5. These treatments were chosen because they are the most used in stromatolite samples for geochemical analysis. To compare the impact of the organic matter removal treatments in stromatolite samples we also processed them as regular carbonate samples for radiocarbon analysis, with no organic matter removal (control samples). X-ray diffraction and X-ray fluorescence have been used to obtain mineral and elemental characterization, respectively. H2O2 could not influence the results of Mg-calcite concentrate samples. The use of NaOCl appears to have been effective in preserving more material than H2O2 independent of the mineralogical composition of the stromatolite layers. The F14C results after HCl etching for Mg-calcite concentrated samples were similar to those without etching suggesting that the HCl etching does not impact the results in this case. The organic matter removal is more important than the etching procedure for stromatolite samples. NaOCl is more indicated to be used as chemical pretreatment for radiocarbon analysis purposes independent of the mineral matrix of samples.

Illegal poaching brought elephant species to the brink of extinction; therefore, international trade in ivory has become regulated by the Convention on International Trade in Endangered Species of Flora and Fauna (CITES). However, the trade is still allowed for antique items, standing for ivory from a period before 1947 within the European Union. This could serve as a loophole for the laundering of modern ivory. In the described case of the Happy Fisherman statuette, the traded item was declared to be antique, but radiocarbon analysis proved a modern provenance, and the statuette was confiscated. The radiocarbon analysis was later confirmed by information from a Chinese newspaper found inside the statuette. Based on the findings, we strongly recommend careful consideration of each individual ivory piece offered for sale, with a thorough inspection of the items and related documentation carried out by a relevant CITES authority. Any exemption of the commercial ban should be granted only to those applicants who meet the criteria of proper evidence in the form of scientific analysis or reliable and trustworthy documentation.

This study presents a series of new radiocarbon dates and the first stable carbon and nitrogen isotope measurements of C3 cereal grains from Roman Iron Age (1–400 AD) archaeobotanical assemblages in Lithuania, southeastern Baltic region. These data are complemented by stable isotope measurements of faunal remains to assess local environmental conditions and evaluate human impact on the landscape through agricultural practices. The δ15N and δ13C values indicate that agriculture during this period relied heavily on intensive manuring and cultivation in open, well-irrigated landscapes. The results also reveal diverse cultivation strategies across sites, with isotopic differences between rye and barley suggesting the possible use of an infield–outfield cultivation system. Radiocarbon dates indicate that these agricultural innovations may have started as early as the 1st to mid-2nd century AD with the introduction of rye, however the evidence points to a gradual and uneven adoption rather than a rapid uniform shift.

Ocean radiocarbon (14C) is a proxy for air-sea exchange, vertical and horizontal mixing, and water mass identification. Here, we present five pre- to post-bomb coral Δ14C records from West Flower Garden Bank and Santiaguillo reefs in the Gulf of Mexico, Boca de Medio, and Isla Tortuga near the Cariaco Basin north of Venezuela. To assess basin-wide Δ14C variability, we compiled the Atlantic Ocean reef-building surface coral Δ14C records (24 corals and 28 data sets in total) with these new records. Cumulatively, the Δ14C records, on their independent age models, reveal the onset of post-bomb Δ14C trends in 1958 ±1 to 2 years. A general decrease in maximum Δ14C values occurs with decreasing latitude reflecting the balance between air-sea gas exchange and surface water residence time, vertical mixing, and horizontal advection. A slightly larger atmospheric imprint in the northern sites and relatively greater vertical mixing and/or advection of low-14C waters influence the southern Caribbean and eastern Atlantic sites. The eastern Atlantic sites, due to upwelling, have the lowest post-bomb Δ14C values. Equatorial currents from the eastern Atlantic transport low Δ14C water towards the western South Atlantic and southern Caribbean sites. Decadal Δ14C averages for the pre-bomb interval (1750–1949) for the low latitude western Atlantic are relatively constant within analytical (3–5‰) and chronological uncertainties (∼1–2 years) due to mixing and air-sea exchange. The compiled Δ14C records provide updated regional marine Δ14C values for marine reservoir corrections.

During the last decade, early Neolithic sites with unique flat-bottomed pottery as distinguishing feature were discovered in the southern part of Western Siberia at the Baraba forest-steppe and identified as the Early Neolithic Baraba Culture (briefly, Baraba culture). The culture is represented in settlements and ritual complexes, has households, as well as implements made of stone and bone. Samples of mammal bones, bird bones and bone artifacts were collected from three sites of the Baraba Culture: Vengerovo-2, Tartas-1, and Ust-Tartas mounds, and dated by accelerator mass-spectrometry (AMS) to reconstruct the chronology of the sites. 36 reliable radiocarbon dates were obtained: 12 of them at the Curt-Engelhorn-Centre of Archaeometry (Mannheim, Germany) and 24 at the AMS Golden Valley (Novosibirsk, Russia). Minimal-to-no differences between radiocarbon dates assessed at GV and MAMS facilities were identified by Bayesian analysis of covariance/analysis of variance. Bayesian chronological modeling supports existence of the Baraba culture between the middle of 8th millennium BC till the start of 6th millennium BC. Two stages of sites’ use were identified, separated by the transitory period of uncertain duration lasting since the end of 7th millennium. The end of the first stage was followed by abandonment of the Tartas-1 site, which we suggest coincided with the start of the 8.2k climatic event.1

A 350 14C yr discrepancy was found between dates on postcranial remains and mandibular teeth on what was thought to be the same individual from the Early Neolithic cemetery of Shamanka II, Lake Baikal. Stable nitrogen isotope results suggested a major shift in diet between childhood (when the teeth formed) and adulthood (represented by the postcrania), which could have resulted in different 14C ages through a freshwater reservoir effect. Subsequent additional dating on the mandible and postcranial elements, however, indicated that the mandible actually belonged to a different individual. More subtle reservoir effects can be seen on the sequentially forming teeth and mandible. The practice by prehistoric hunter-gatherers of Lake Baikal of re-opening graves and removing cranial elements has long been known, but this is the first evidence for the inclusion of a mandible from a separate individual, though whether it was intentional or incidental is uncertain. As well as providing new insights into mid-Holocene mortuary practices in the region, our findings raise a cautionary note for the examination of disturbed graves.

Western Zhou Dynasty (ca. 1046–771 BC) was established soon after conquering the Shang Dynasty (ca. 1600–1046 BC) and brought about the earliest enfeoffment system in Chinese history. Yan was one of the vassal states of the same clan as Zhou. According to historical records, the capital of Yan state was located near Yan mountain, which is now known as the Liulihe site in the Fangshan District, Beijing. This study carries out the high-precision dating of two newly discovered Western Zhou Dynasty noble tombs at the Liulihe site. The man in tomb M1902 participated in the groundbreaking ceremony of Yan’s capital according to inscriptions on the bronze vessel found in this tomb. Samples of different materials, especially different parts of human skeletons from the tombs, were selected to form a sample series in chronological order. Wiggle-matching models were established in OxCal program based on the growth and development time of different teeth and bones of human skeletons. More accurate ages were acquired for the death of the individuals. The results indicate that the most probable distribution range of the death date of the individual in M1902 is about 1045–1010 BC. The radiocarbon dates of M1902 give important chronological information about the founding of Yan state, and they are very close to those of the year in which King Wu of Zhou conquered the Shang Dynasty.

Ever since the first discovery of urn burials in eastern Serbia during the 1980s, their dating has been uncertain and based on distant analogies and typological parallels. In this paper, we present radiocarbon dates from five urn cemeteries and three associated settlement sites, showing that the initial dating (Late Bronze Age; 14th–11th BCE) is highly questionable. Instead, radiocarbon dating and modeling presented here connect the urn cemeteries—characterized by a specific grave architecture and associated with settlements that display evidence of copper production—to a period between the 20th and 16th centuries BC. The fact that many of our dates come from cremated bones requires a discussion with regard to the circumstances of carbon exchange during cremation. The absolute dates thus far available for most urn cemeteries from the neighboring regions of the Balkans are all markedly younger (15th–11th century BC) than the data presented here and fall in the frame of the overall expansion of cremation in Europe during the Urnfield period. The new absolute dates from eastern Serbia provide a possibility to change our understanding of the Bronze Age dynamics of the 2nd millennium in the broader area of southeastern Europe and indicate a much earlier acceptance of cremation among certain groups than previously thought.

The chronology of the Bronze Age in the Carpathian basin is largely based on relative chronologies, i.e. stylistic analysis of ceramic (and other) materials. While the number of radiocarbon dates is generally increasing, certain important sites are still poorly dated. One of the largest necropolises from this period, i.e. Mokrin necropolis, which traditionally belongs to Maros culture, is dated only with 6 radiocarbon dates. Here we synthesize the previous 6 radiocarbon dates with 13 new radiocarbon dates, with two goals in mind: 1) to explore the absolute chronology of the site, specifically to determine its chronological limits; and 2) to test hypotheses about the spatio-temporal organization of the site. Our data show that the chronological limits of the necropolis were most probably between 2073 and 1822 BC. Concerning traditional relative chronologies, none of the previous hypotheses about the internal chronological development of the necropolis is supported by data. Our results suggest that all parts of the necropolis were used relatively simultaneously.

The dietary habits of Neanderthals are considered an issue of great interest in the literature and have opened an important number of fruitful debates. Indeed, understanding diets can provide important information regarding issues of palaeoenvironmental reconstructions and subsistence strategies. In this respect, dental remains can play a vital role in the conducted efforts to reconstruct the palaeoecological niches securely and accurately since dental microwear analyses have precisely detected dietary patterns of the populations in the past. In this context, the Iberian Peninsula forms an interesting model for examining Neanderthal populations, their subsistence strategies, and adaptive skills. This study aims the examination of already published data in order to provide a holistic approach regarding the dietary habits of H. neanderthalensis populations in the Iberian Peninsula, along with the importance of the utilization of dental microwear analysis in the archaeological record.

Marine aerosols can enter the terrestrial environment via sea spray which is known to affect the stable isotope fingerprint of coastal samples (plants, animals/humans), including δ13C. However, the impact of sea spray on 14C dating of terrestrial organisms at coastal sites has not been investigated so far. Besides a direct effect, sea spray is accompanied by physiological effects, e.g., due to salinity. In an artificial sea spray experiment in the greenhouse, the effect of sea spray on 14C in plant tissue was investigated. Beach grass was sprayed with mineral salt solutions containing only traces of NaCl or with brackish water from the Schlei inlet or the Baltic Sea. These plants should give a 14C signal close to the modern atmospheric 14CO2 composition. However, three treatment groups showed variable radiocarbon concentrations. Plants sprayed with water from the Schlei inlet, Baltic Sea water, or with a mineral salt solution with very high HCO3– concentration are depleted in 14C content relative to contemporary atmospheric composition. While δ13C reflects physiological effects in the plants, caused either by salinity (NaCl) or HCO3– stress, resulting in decreased discrimination against 13C, the uptake of high amounts of 14C (ca. 53–67%) from DIC (dissolved inorganic carbon) partly masks the underlying physiological reactions, as is visible in the radiocarbon signature of the plant tissues. This preliminary study indicates that sea spray effects on plant tissue could potentially influence faunal tissue 14C composition at coastal sites. Further research is required to better understand the observed reservoir effect.

The Manych Depression is a relatively narrow elongated depression of tectonic origin, connecting the Caspian and Azov-Black Sea basins. The Caspian Sea repeatedly discharged its waters through this depression into the Black Sea and further into the Mediterranean Sea during the Quaternary period. The last discharge occurred in MIS 2 when the Khvalynian transgression waters exceeded the drainage divide between those two basins. The geochronology of the last flow of Caspian waters into the Black Sea was established recently based on 14C dating of Khvalynian shells, carried out mainly by liquid scintillation counting, and the end of this event was dated to 12.5–12.8 ka cal BP. Recently obtained OSL dates for one of the most complete sections of the Khvalynian deposits of the Manych Depression indicate an older time for the end of the flow. This study aimed to clarify the timing of the Khvalynian transgression discharge by examining two sections containing the Khvalynian mollusk fauna in layers that, according to their stratigraphic and geomorphological position, belong to the final phase of the flow of the Caspian waters. Four 14C AMS dates were obtained from single shells of Didacna ebersini and Hypanis plicata, which agree with the OSL dating results. The results indicate that the last overflow of Caspian waters through the Manych Depression had ceased at around 14.5 ka cal BP.

Plague and famine are two of the worst killers in human history. Both struck the Czech lands in the Middle Ages not long after each other (the famine of 1318 CE and the plague of 1348–1350 CE). The aim of our study was to try to relate the mass graves found in the vicinity of the Chapel of All Saints with an ossuary in the Kutná Hora–Sedlec site to these two specific events. For this purpose, we used stratigraphic and archaeological data, radiocarbon dating, and Bayesian modeling of 172 calibrated AMS ages obtained from teeth and bones of 86 individuals buried in the mass graves. Based on the stratigraphic and archaeological data, five mass graves were interpreted as famine graves and eight mass graves were interpreted as plague graves. Using these data and the calibration of the radiocarbon results of the tooth-bone pairs of each individual, we constructed the Bayesian model to interpret the remaining mass graves for which no contextual information was available (eight mass graves). In terms of Bayesian model results, the model fits stratigraphic data in 23 out of 34 cases and in all seven cases based on calibration data. To validate the model results on archaeologically and stratigraphically uninterpreted data, ancient DNA analysis is required to identify Yersinia pestis.

An international consortium of radiocarbon laboratories has established the origin of the Church of St. Margaret of Antioch in Kopčany (Slovakia), because its age was not well known from previous investigations. In total, 13 samples of charcoal, wood, mortar, and plaster were analyzed. The 14C results obtained from the different laboratories, as well as between the different sample types, were in good agreement. Resulting the final 14C calibrated age of the Church, based on dating a single piece of a wooden levelling rod is 774–884 AD (95.4% confidence level), which is in very good agreement with Bayesian modeling result based on dating of wood, charcoal and mortar samples (788–884 AD, 95.4% confidence level). The probability distribution from OxCal calibration shows that 79% of the probability distribution lies in the period before 863 AD, implying that the Church could have been constructed before the arrival of Constantine (St. Cyril) and St. Methodius to Great Moravia. If we take as the terminus post quem the documented date of consecration of the church in Nitrava (828 AD), the Bayesian modeling suggests the age of the Church in the range of 837–884 AD (95.4% confidence level). Although the 14C results have very good precision, the specific plateau shape of the calibration curve in this period caused a wide range of the calibrated age. The Church represents, together with the St. George’s Rotunda in Nitrianska Blatnica, probably the oldest standing purpose-built Christian church in the eastern part of Central Europe.