Search results

Measurement of the elemental composition of shells is increasingly emerging as an avenue for obtaining high-resolution insights into paleoclimate and past seasonality. Several studies have shown significant correlations between Mg/Ca ratios measured on shell carbonate and the sea surface temperature (SST) within which this carbonate was precipitated. However, other investigations have reported large variability in this relationship between species. Therefore, further studies, including taxa previously not considered are still required in order to validate these new species as suitable climate proxies. Here, we measured Mg/Ca ratios for limpet Patella depressa Pennant, 1777 samples live-collected in northern Spain for the first time. The elemental ratio was measured using laser-induced breakdown spectroscopy (LIBS), a technique that significantly decreases the time required for sample preparation and increases the number of shells that can be analyzed. In this study, calibration-free LIBS (CF-LIBS) methods were applied to estimate molar concentrations of chemical elements on biogenic calcium carbonate. The Mg/Ca ratio evolution along the shell growth axis was compared with stable oxygen isotope (δ18O) profiles obtained from these same limpets and the SST at the place where the mollusk grew to determine if the sequences obtained correctly reflected environmental conditions during the life-span of the mollusk. The results showed a significant correlation between Mg/Ca ratio series and both δ18O profiles and SST, highlighting the paleoenvironmental and archaeological potential of LIBS analyses on this mollusk species that is frequently found in archaeological contexts in the western Europe. ; This research was performed as part of the projects HAR2016-75605-R, HAR2017-86262-P and PID2019-107270RB-C21/AEI/10.13039/501100011033, funded by the Spanish Ministry of Economy and Competitiveness, MINECO. During the development of this research A.G.E was funded by the Basque Country Postdoctoral Program through a postdoctoral grant (POS_2020_2_0032). This study has also been supported by the Prehistoric Research Consolidated Group of the Basque Country University (IT-1223-19), funded by the Basque Country Government. P.R. is funded by the Max Planck Society.

A large number of sites dated to the Late Middle Paleolithic and the Early Upper Paleolithic have been recorded in the Cantabrian region (northern Iberia), making this area a key location to investigate the lifeways of the last Neanderthals and the first anatomically modern humans. The stratigraphic sequence from El Cuco rock-shelter was originally attributed to the Early Upper Paleolithic based on radiocarbon dates measured on bone apatite. However, new radiocarbon dates on shell carbonates from the lower levels produced inconsistent dates with those previously published. In order to clarify this anomaly, a reassessment of the chronology of levels VI to XIV was undertaken. The review was based on new radiocarbon dates performed on bones and shells, and a re-evaluation of the lithic assemblages. Bone samples did not produce radiocarbon dates due to a lack of collagen preservation but radiocarbon dating of shell carbonates provided dates ranging from 42.3 to 46.4 ka BP. These dates are significantly older than that previously obtained for level XIII using biogenic apatite from bones (?30 ka uncal BP), suggesting that the bone apatite used for radiocarbon dating was rejuvenated due to contamination with secondary carbonate. Lithic assemblages, defined in the first place as Evolved Aurignacian, have now been confidently attributed to the Mousterian techno-complex. These results suggest a Middle Paleolithic chronology for this part of the sequence. The new chronology proposed for El Cuco rock-shelter has significant implications for the interpretation of Neanderthal subsistence strategies and settlement patterns, especially for coastal settlement and use of marine resources, not only in northern Iberia, but also in Atlantic Europe. ; Radiocarbon dates OxA-27196 and OxA-27730 were funded by the NERC Radiocarbon Facility (NF/2012/1/18) and they were part of the project NF100413 (Newton International Fellowship to IGZ). Radiocarbon dates OxA-30851, P-32155 (ORAU) and UGAMS-9076 were part of the project HAR2013-46802-P funded by the Spanish Ministry of Economy and Competitiveness. Two other samples that failed to be dated at the ORAU (P-35524 and P-35523) as well as the date Beta – 382682 and elemental analysis were obtained in the project HAR2010-22013, funded by the Spanish Ministry of Science and Innovation. Isotopic analysis was performed as part of the projects HAR2012-33956 funded by the Spanish Ministry of Economy and Competitiveness and EUROREFUGIA (Ref. 322112) funded by the European Union through FP7-PEOPLE-2012-CIG (https://eurorefugia.wordpress.com/), with additional support from the Max Planck Society. IGZ and ABMA were funded by the Juan de la Cierva (JCI-2012-12094) and the Ramón y Cajal (RYC-2011-00695) Research Programmes of the Spanish Ministry of Economy and Competitiveness, respectively

The cooling and drying associated with the so-called '8.2 ka event' have long been hypothesized as having sweeping implications for human societies in the Early Holocene, including some of the last Mesolithic hunter-gatherers in Atlantic Europe. Nevertheless, detailed 'on-site' records with which the impacts of broader climate changes on human-relevant environments can be explored have been lacking. Here, we reconstruct sea surface temperatures (SST) from ?18O values measured on subfossil topshells Phorcus lineatus exploited by the Mesolithic human groups that lived at El Mazo cave (N Spain) between 9 and 7.4 ka. Bayesian modelling of 65 radiocarbon dates, in combination with this ?18O data, provide a high-resolution seasonal record of SST, revealing that colder SST during the 8.2 ka event led to changes in the availability of different shellfish species. Intensification in the exploitation of molluscs by humans indicates demographic growth in these Atlantic coastal settings which acted as refugia during this cold event. ; This research was performed as part of the projects HAR2016-75605-R and HAR2017-86262-P, funded by the Spanish Ministry of Economy and Competitiveness, MINECO. During the development of this research AGE was funded by the University of Cantabria through a predoctoral grant (no code available), by the Basque Country Postdoctoral Programme (Grant number POS_2020_2_0032), by the University of La Rioja through a posdoctoral grant (no code available) and he is currently supported by the Catalonia Postdoctoral Programme through a Beatriu de Pinos fellowship (grant number 2020 BP 00240). ABMA was funded by the SUBSILIENCE ERC-CoG project (Grant agreement No. 818299). This study has also been supported by the Prehistoric Research Consolidated Group of the Basque Country University (IT1223-19), funded by the Basque Country Government. We thank the Max Planck Institute for Science of Human History (MPI-SHH), University of Cantabria (UC), Instituto Internacional de Investigaciones Prehistoricas de ...