New criteria for choosing measurement strategies and assessing data quality allow better comparison of XRF results.

Giant gastropods are among the largest mollusks in the fossil record, but their potential as paleoseasonality archives has received little attention. Here, we combine stable isotope and trace element analyses with microscopic observations and growth modeling on shells of two species of the gastropod genus Campanile: the extinct Campanile giganteum from Lutetian (~45 Ma) deposits in the Paris Basin (France), the longest gastropod known from the fossil record, and its modern relative Campanile symbolicum from southwestern Australia. The C. giganteum shells contain original aragonite and have pristine nacre in their apertures. We show that these gastropods attained growth rates exceeding 600 mm/year along their helix, depositing over 300 cm 3 aragonite per year. High growth rates and excellent preservation make C. giganteum excellent archives for reconstructing environmental change at high (potentially daily) temporal resolution, while providing enough material for methods such as clumped isotope analysis. Growth models show that Campanile gastropods grew nearly year-round, albeit slower in winter. Stable oxygen isotope ratios in modern C. symbolicum faithfully record a seasonal variability of 18-25°C in sea surface temperature, only failing to record the coolest winter temperatures (down to~16°C). Similarly, C. giganteum specimens likely record a nearly complete seasonal temperature range. Assuming constant sea water isotope composition, their oxygen isotope seasonality of up to 2.5‰ would translate to a Lutetian temperature range of 21-32°C in the Paris Basin. We hypothesize that these high and seasonally variable temperatures formed the breeding ground for the Lutetian shallow marine biodiversity hotspot in the Paris Basin.

The reconstruction of palaeoclimate on a sub-annual scale requires the measurement of chemical proxies in fossil material at a high spatial resolution. While various methods for trace element analysis on the micrometre scale are available, they are usually destructive to the sample or not widely accessible. This study evaluates the performance of a table-top micro X-ray fluorescence scanner in obtaining reproducible trace element profiles on bivalve calcite. Standard calibration and repeatability tests demonstrate the robustness of results obtained with this new generation micro X-ray fluorescence device that uses a comparatively high excitation energy of 30 W. Results show that elemental abundances measured using this fast, readily accessible and non-destructive analytical set-up are reproducible on the lg g À1 level, and therefore suitable for the analysis of the abundance of commonly studied elements in bivalve calcite (for example, Sr, Mn and Fe). Spectra obtained in this study show considerable improvement in terms of signal to noise ratio compared to earlier table-top micro X-ray fluorescence studies. Reliability of the measurements is tested using a conservative detection and quantification limit. Count rates of Ca are used to check for point measurements disturbed by irregularities on the sample surface. Furthermore, the method allows semi-quantitative two-dimensional element mapping, which is a convenient tool for the detection of diagenetic alteration in fossil samples. The method reveals records of Sr/Ca, Fe/Ca and Mn/Ca ratios in a Late Campanian Vaccinites vesiculosus shell, with Sr/Ca ratios showing a trend opposite to Mn/Ca and Fe/Ca. Resulting trace element records are discussed in terms of seasonal cyclicity in the Late Cretaceous and diagenetic alteration of the fossil shell.

The coexistence of cultural identities and their interaction is a fundamental topic of social sciences that is not easily addressed in prehistory. Differences in mortuary treatment can help approach this issue. Here, we present a multi-isotope study to track both diet and mobility through the life histories of 32 broadly coeval Late Neolithic individuals interred in caves and in megalithic graves of a restricted region of northern Iberia. The results show significant differences in infant- and child-rearing practices, in subsistence strategies, and in landscape use between burial locations. From this, we posit that the presence of communities with distinct lifestyles and cultural backgrounds is a primary reason for Late Neolithic variability in burial location in Western Europe and provides evidence of an early “them and us” scenario. We argue that this differentiation could have played a role in the building of lasting structures of socioeconomic inequality and, occasionally, violent conflict.