This study is first attempt to refine Early Iron Age absolute chronology, specifically the timing of the Hallstatt C-D transition in southern Germany, using Bayesian chronological modelling of radiocarbon (¹⁴C) dates. The Hallstatt period (c.800–450 BC) marks the transition from prehistory to proto-history in Central Europe. The relative chronological framework for Hallstatt burials developed by the mid-twentieth century is still used today, but absolute dating is limited by the scarcity of dendrochronological dates and the perception that ¹⁴C dating in the Hallstatt period (HaC-HaD) is futile, due to the calibration plateau between c.750 and 400 cal BC. We present new AMS ¹⁴C dates on 16 HaC-HaD burials from a stratified sequence at Dietfurt an der Altmühl ‘Tennisplatz’ (Bavaria, Germany). This sequence is situated entirely on the ‘Hallstatt plateau’, but by combining ¹⁴C dating with osteological, stratigraphic, and typological information, we demonstrate that the plateau is no longer the ‘catastrophe’ for archaeological chronology once envisaged. Taking into account dendrochronological dating elsewhere, we show that at Dietfurt, the HaC-HaD transition almost certainly occurred before 650 cal BC, and most likely between 685 and 655 cal BC (68.3% probability), several decades earlier than usually assumed. We confirm the accuracy and robustness of this estimate by sensitivity testing. We suggest that it is now possible, and essential, to exploit the increased precision offered by AMS measurement and the IntCal20 ¹⁴C calibration curve to re-evaluate absolute chronologies in Early Iron Age Europe and equivalent periods in other regions.

Radiocarbon (¹⁴C) results on cremated bone are frequently published in high-ranking journals, but ¹⁴C laboratories employ different pretreatment methods as they have divergent perceptions of what sources of contaminants might be present. We found pretreatment protocols to vary significantly between three laboratories (Brussels [RICH], Kiel [KIA], and Groningen [CIO]), which all have a long history of dating cremated bone. We present a case study of 6 sets of replicate dates, to compare laboratory pretreatment protocols, and a further 16 sets of inter-laboratory replicate measurements, which compare specific steps of the conversion and measuring process. The ¹⁴C results showed dates to be reproducible between the laboratories and consistent with the expected archaeological chronology. We found that differences in pretreatment, conversion to CO₂ and accelerator mass spectrometry (AMS) measurement to have no measurable influence on the majority of obtained results, suggesting that any possible diagenesis was probably restricted to the most soluble ≤5% of each sample, as this proportion of the sample mass was removed under all laboratory protocols.

Experimental studies have shown that significant carbon exchange occurs between bone-apatite and the pyre atmosphere during cremation, which can cause a calendar date offset between the radiocarbon (14C) event and the date of cremation. There are limited empirical data available to assess the magnitude of such wood-age offsets, but the aim of this paper is to test if they can be modeled statistically. We present new 14C dates on modern bone cremated in realistic open-air experiments and on archaeological samples of cremated bone and associated organic material. Experimental results demonstrate a wide range of carbon exchange with a mean of 58.6 ± 14.8%. Archaeological results indicate that the wood-age offsets have an approximately exponential distribution. We test whether the default Charcoal Outlier_Model in OxCal v4.3, developed to reduce the impact of wood-age offsets in dates of charcoal, is appropriate for cremated bone, but find that it slightly underestimates apparent offsets. To counter the intrinsic age of both pyre fuel and unburned bio-apatite, we instead propose a bespoke Cremation Outlier_Model, which combines an exponential distribution of calendar age offsets with a minimum offset, and provides better estimates of the actual dates of cremations.

This article presents a series of recommendations for the publication of archaeological data, to improve their usability. These 12 recommendations were formulated by archaeological data experts who mined thousands of publications for different data types (including funerary practices, accelerator mass spectrometry dating, stable isotopes, zooarchaeology, archaeobotany and pathologies) during the initial construction of the Big Interdisciplinary Archaeological Database (BIAD). We also include data harmonisation vocabularies utilised for the integration of data from different recording systems. The case studies we cite to illustrate the recommendations are grounded in examples from the published literature and are presented in a problem/solution format. Though practically oriented towards the facilitation of efficient databasing, these recommendations – which we refer to as the BIAD Standards – are broadly applicable by those who want to extract scientific data from archaeological information, those who work with a specific region or theoretical focus and journal editors and manuscript authors. We anticipate that the use of the BIAD Standards will increase the usability, visibility, interoperability and longevity of published data and also increase the citations of those publications from which data were mined. The Standards will also help frame a unified foundation to support the continued integration of the natural sciences with archaeological research in the future.

Multiple burial in medieval burial grounds are often interpreted as a result of disease, but it is difficult to test such hypotheses, as most acute infectious diseases leave no visible evidence on skeletal material. Scientific dating can potentially associate multiple burials with historically documented epidemics, but the precision required to exclude alternative explanations would normally be attainable only by dendrochronology. Here, we argue that by combining archaeological, osteological and paleodiet research in a Bayesian framework, we can exploit differences in dietary reservoir effects to refine the dates of multiple burials, and potentially date such events to within a range of <20 years. We present new radiocarbon (¹⁴C) and stable isotope (δ¹³C, δ¹⁵N) results from a medieval multiple grave at St Alban’s Odense, on the island of Funen in central Denmark. We show the ca. 150-yr spread in¹⁴C ages of the five juveniles is compatible with differences in the amount of fish they consumed. Our chronological model, which combines marine reservoir effect correction with calendar age offsets based on osteological evidence, dates the multiple burial tocal AD 1425–1445(95% probability), an interval in which two plague epidemics took place in Denmark.

This study presents the first extensive radiocarbon dating programme of Bronze Age material from northern Germany, and it combines radiocarbon dates, relative typo-chronological date ranges, and stratigraphic data within a Bayesian chronological framework. We estimate the cemetery complex at Mang de Bargen (Bornhöved, distr. Segeberg, Schleswig-Holstein) to be in use for more than two millennia, which is exceptionally long in northern Germany and in a wider European context. The site provides a unique insight into the dynamic nature of burial monuments and associated burial practices, from the Late Neolithic and into the Pre-Roman Iron Age (c. 2500–50 bc). The barrow building tradition lasted around a millennium (c. 2350 –1300 bc), with several barrows in concurrent use. The barrows were persistently re-used as burial ground, both within ‘living memory’ of the primary graves, but also long after. The burial intensity varied over the cemetery’s use-life, with distinct peaks in the Late Neolithic, when the first barrows were erected; in the Older Bronze Age when more barrows were erected; in the Younger Bronze Age, when secondary cremation graves were added to existing barrows; and finally in the Pre-Roman Iron Age, with the addition of an urnfield. The funerary rituals vary considerably over the period: from inhumation to cremation, and from primary and secondary graves in barrows to flat graves. Cremation was introduced in the 14th century bc but inhumation and cremation were used in parallel for around a century before the former ritual was abandoned c. 1300 bc. The study provides absolute chronological distributions of the grave types present at Mang de Bargen and shows them to be comparable to other sites at a regional and over-regional scale, successfully demonstrating how new types were quickly adopted across large parts of north-western Europe.