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The dingo is the only placental land mammal aside from murids and bats to have made the water crossings to reach Australia prior to European arrival. It is thought that they arrived as a commensal animal with people, some time in the mid Holocene. However, the timing of their arrival is still a subject of major debate with published age estimates varying widely. This is largely because the age estimates for dingo arrival are based on archaeological deposit dates and genetic divergence estimates, rather than on the dingo bones themselves. Currently, estimates vary from between 5000–4000 years ago, for finds from archaeological contexts, and as much as 18,000 based on DNA age estimates. The timing of dingo arrival is important as post arrival they transformed Indigenous societies across mainland Australia and have been implicated in the extinction of a number of animals including the Tasmanian tiger. Here we present the results of direct dating of dingo bones from their oldest known archaeological context, Madura Cave on the Nullarbor Plain. These dates demonstrate that dingoes were in southern Australia by between 3348 and 3081 years ago. We suggest that following their introduction the dingo may have spread extremely rapidly throughout mainland Australia.

Radiocarbon dating uses the decay of a radioactive isotope of carbon (14C) to measure time and date objects containing carbon-bearing material. With a half-life of 5,700 ± 30 years, detection of 14C is a useful tool for determining the age of a specimen formed over the past 55,000 years. In this Primer, we outline key advances in 14C measurement and instrument capacity, as well as optimal sample selection and preparation. We discuss data processing, carbon reservoir age correction, calibration and statistical analyses. We then outline examples of radiocarbon dating across a range of applications, from anthropology and palaeoclimatology to forensics and medical science. Reproducibility and minimum reporting standards are discussed along with potential issues related to accuracy and sensitivity. Finally, we look forwards to the adoption of radiocarbon dating in various fields of research thanks to continued instrument improvement.Radiocarbon dating is a common and reliable tool for measuring the age of a range of objects, from trees to historical artefacts and human remains. Hajdas et al. outline best practices for selecting and processing samples, as well as obtaining accurate measurements and age ranges. Ethical considerations for rare and culturally valuable materials are discussed.

Recent theories for glacial–interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a “bipolar ventilation seesaw.” However, the viability of this hypothesis has been contested, and robust evidence in its support is lacking. Here we present a record of North Atlantic deep-water radiocarbon ventilation, which we compare with similar data from the Southern Ocean. A striking coherence in ventilation changes is found, with extremely high ventilation ages prevailing across the deep Atlantic during the last glacial period. The data also reveal two reversals in the ventilation gradient between the deep North Atlantic and Southern Ocean during Heinrich Stadial 1 and the Younger Dryas. These coincided with periods of sustained atmospheric CO ₂ rise and appear to have been driven by enhanced ocean–atmosphere exchange, primarily in the Southern Ocean. These results confirm the operation of a bipolar ventilation seesaw during deglaciation and underline the contribution of abrupt regional climate anomalies to longer-term global climate transitions.

Polynesians introduced the tropical crop taro (Colocasia esculenta) to temperate New Zealand after 1280 CE, but evidence for its cultivation is limited. This contrasts with the abundant evidence for big game hunting, raising longstanding questions of the initial economic and ecological importance of crop production. Here we compare fossil data from wetland sedimentary deposits indicative of taro and leaf vegetable (including Sonchus and Rorippa spp.) cultivation from Ahuahu, a northern New Zealand offshore island, with Raivavae and Rapa, both subtropical islands in French Polynesia. Preservation of taro pollen on all islands between 1300 CE and 1550 CE indicates perennial cultivation over multiple growing seasons, as plants rarely flower when frequently harvested. The pollen cooccurs with previously undetected fossil remains of extinct trees, as well as many weeds and commensal invertebrates common to tropical Polynesian gardens. Sedimentary charcoal and charred plant remains show that fire use rapidly reduced forest cover, particularly on Ahuahu. Fires were less frequent by 1500 CE on all islands as forest cover diminished, and short-lived plants increased, indicating higher-intensity production. The northern offshore islands of New Zealand were likely preferred sites for early gardens where taro production was briefly attempted, before being supplanted by sweet potato (Ipomoea batatas), a more temperate climate-adapted crop, which was later established in large-scale cultivation systems on the mainland after 1500 CE.

Since the 1970s, monumental stone structures now called mustatil have been documented across Saudi Arabia. However, it was not until 2017 that the first intensive and systematic study of this structure type was undertaken, although this study could not determine the precise function of these features. Recent excavations in AlUla have now determined that these structures fulfilled a ritual purpose, with specifically selected elements of both wild and domestic taxa deposited around a betyl. This paper outlines the results of the University of Western Australia’s work at site IDIHA-0008222, a 140 m long mustatil (IDIHA-F-0011081), located 55 km east of AlUla. Work at this site sheds new and important light on the cult, herding and ‘pilgrimage’ in the Late Neolithic of north-west Arabia, with the site revealing one of the earliest chronometrically dated betyls in the Arabian Peninsula and some of the earliest evidence for domestic cattle in northern Arabia.

We present a high-resolution seawater radiocarbon (Δ14C) record from a Porites coral collected from Masthead Island in the southern Great Barrier Reef (GBR) covering the years 1945–2017. The Δ14C values from 1945–1953 (pre-bomb era) averaged –49‰. As a result of bomb-produced 14C in the atmosphere, Δ14C values started to rise rapidly from 1959, levelled off at ∼131‰ in the late 1970s and gradually decreased to ∼40.3‰ by 2017 due to the decrease in the air-sea 14C gradient and the overturning of the 14C ocean reservoir (i.e., surface ocean to subsurface ocean; atmosphere to surface ocean). The Masthead Island record is in agreement with previous 14C coral records from the southern GBR. A comparison between surface ocean and atmospheric Δ14C suggests that, since 2010, the main reservoir of bomb-derived 14C has shifted from the atmosphere to the surface ocean, potentially resulting in reversed 14C flux in regions where the CO2 gradient is favorable. The high-resolution Masthead coral Δ14C sheds light on long-term variability in air-sea exchange and GBR regional ocean dynamics associated with climate change and in conjunction with the previous records provides a robust seawater 14C reference series to date other carbonate samples.

The timing, rate, and magnitude of rapid sea-level rise during Meltwater Pulse 1B (MWP-1B, ~11.45–11.1 ka) remain controversial. Robust constraints on past MWPs are crucial to future predictions of global ice sheet instability. Using 154 new and existing U/Th and calibrated 14 C-AMS dates from coral, algae, and microbialites recovered during Integrated Ocean Drilling Program Expedition 325, this study reconstructs reef development and relative sea-level (RSL) rise on the Great Barrier Reef (GBR). We identify 107 in situ RSL index points while refining estimates of vertical accretion and paleowater depth. Results show RSL rise during MWP-1B did not exceed 10.2–7.7 m or rates of 30–23 mm/yr, and was likely less. The GBR did not drown, indicating resilience to MWP-1B. These findings are more consistent with Tahiti and other Pacific records and do not support the Barbados record of MWP-1B as an abrupt step in global sea level, with a magnitude > 11 m. An international team of scientists recovered fossil coral reef samples from the shelf edge of the Great Barrier Reef to reconstruct past reef development and rapid relative sea level rise, including constraints on Meltwater Pulse 1B (11.45–11.1 ka).

Deep-sea corals are found on hard substrates on seamounts and continental margins worldwide at depths of 300 to [almost equal to]3,000 m. Deep-sea coral communities are hotspots of deep ocean biomass and biodiversity, providing critical habitat for fish and invertebrates. Newly applied radiocarbon age dates from the deep water proteinaceous corals Gerardia sp. and Leiopathes sp. show that radial growth rates are as low as 4 to 35 μm year⁻¹ and that individual colony longevities are on the order of thousands of years. The longest-lived Gerardia sp. and Leiopathes sp. specimens were 2,742 years and 4,265 years, respectively. The management and conservation of deep-sea coral communities is challenged by their commercial harvest for the jewelry trade and damage caused by deep-water fishing practices. In light of their unusual longevity, a better understanding of deep-sea coral ecology and their interrelationships with associated benthic communities is needed to inform coherent international conservation strategies for these important deep-sea habitat-forming species.

Marine shells incorporate oxygen isotope signatures during growth, creating valuable records of seawater temperature and marine oxygen isotopic compositions. Secondary ion mass spectrometry (SIMS) measures these compositions in situ at finer length‐scales than traditional stable isotope analyses. However, determining oxygen isotope ratios in aragonite, the most common shell mineral, is hampered by a lack of ideal reference materials, limiting the accuracy of SIMS‐based seawater temperature reconstructions. Here, we tested the capability of SIMS to produce seawater temperature reconstructions despite the matrix calibration challenges associated with aragonite. We cultured Anadara trapezia bivalves at four controlled seawater temperatures (13–28°C) and used strontium labeling to mark the start of the temperature‐controlled shell increment, allowing for more spatially precise SIMS analysis. An improved matrix calibration was developed to ensure more accurate bio‐aragonite analyses that addressed matrix differences between the pure abiotic reference materials and the bio‐aragonite samples with intricate mineral‐organic architectures and distinct minor and trace element compositions. We regressed SIMS‐IRMS biases of abiotic and biogenic aragonites that account for their systematic differences in major, minor, and trace elements, allowing for more accurate SIMS analyses of the temperature‐controlled shell increment. The thorough matrix calibration allowed us to provide a SIMS‐based seawater‐corrected oxygen isotope thermometer of T(°C) = 23.05 ± 0.36 − 4.48 · (δ18Oaragonite [‰ VPDB] − δ18Oseawater [‰ VSMOW] ± 0.25) and 103lnαaragonite‐seawater = (17.78 ± 0.88) · 103/T (K) − (29.44 ± 2.40) that agrees with existing aragonitic IRMS‐based thermometer relationships and improves the applicability of SIMS‐based paleo‐environmental reconstructions of marine bio‐aragonites. Plain Language Summary In this study, we grew marine bivalves under tightly constrained aquaculture conditions at four different seawater temperatures and marked the start of the growth period in the shell structure using strontium labeling. The newly grown shell material between the strontium‐labeled increment and the shell edge was analyzed for its oxygen isotopic composition. The compositions were measured in situ using a high resolution ion microprobe and a newly developed analytical post‐processing strategy specifically designed for biomineral samples with mineral‐organic architectures. The strategy involved two reference materials and the major, minor, and trace element content in the shell and the reference materials. The new approach resulted in an accurate and robust model for determining past seawater temperatures from fossil or historic shells based on their oxygen isotope composition at over an order of magnitude finer length scales than traditional oxygen isotope analyses. Key Points Bivalve mollusks were cultured at different temperatures under tightly constrained seawater composition and environmental conditions SIMS δ18O accuracy was improved with a new paired proxy‐like matrix bias correction using major, minor, and trace element abundances The first high‐resolution SIMS‐based stable oxygen isotope calibration for determining modern and ancient seawater temperatures is derived

The South Pacific Gyre (SPG) plays a vital role in regulating Southern Hemisphere climate and ecosystems. The SPG has been intensifying since the twentieth century due to changes in large scale wind forcing. These changes result from variability in the Southern Annular Mode (SAM), causing warming along the eastern SPG which affects local ecosystems. However, our understanding of SPG variability on timescales greater than several decades is poor due to limited observations. Marine sediment cores are traditionally used to determine if recent ocean trends are anomalous, but rarely capture centennial variability in the southwest Pacific and limit our understanding of SPG variability. Here we capture centennial SPG dynamics using a novel high-resolution paleocirculation archive: radiocarbon reservoir ages (R) and local reservoir corrections (∆R) in SPG deep-sea black corals. We find black coral R and ∆R correlates with SAM reconstructions over 0–1000 cal BP and 2000–3000 cal BP. We propose this correlation indicates varying transport of well-ventilated subtropical waters resulting from SPG and SAM interactions. We reconstruct several ‘spin up’ cycles reminiscent of the recent gyre intensification, which has been attributed to anthropogenic causes. This implies gyre strength and SAM show natural co-variability on anthropogenic timescales which should factor into future climate projections.