Search results for "DISEASE"
showing 10 items of 52575 documents
Dating of the hominid (Homo neanderthalensis) remains accumulation from El Sidrón cave (Piloña, Asturias, North Spain): an example of multi-methodolo…
2010
The age of Neanderthal remains and associated sediments from El Sidrón cave has been obtained through different dating methods (14CAMS, U/TH, OSL, ESR and AAR) and samples (charcoal debris, bone, tooth dentine, stalagmitic flowstone, carbonate-rich sediments, sedimentary quartz grains, tooth enamel and land snail shells). Detrital Th contamination rendered Th/U dating analyses of flowstone unreliable. Recent 14C contamination produced spurious age-values from charcoal samples as well as from inadequately pretreated tooth samples. Most consistent 14C dates are grouped into two series: one between 35 and 40 ka and the other between 48 and 49 ka. Most ESR and AAR samples yielded concordant age…
REFINING ESTIMATES FOR THE SEASON OF SHELLFISH COLLECTION ON THE PACIFIC NORTHWEST COAST: APPLYING HIGH-RESOLUTION STABLE OXYGEN ISOTOPE ANALYSIS AND…
2012
Stable oxygen isotopes from estuarine bivalve carbonate from Saxidomus gigantea were analysed combined with high-resolution sclerochronology from modern and archaeological shells from British Columbia, Canada, to determine the seasonality of shellfish collection from the archaeological site of Namu. The combination of high-resolution sclerochronology and a micro-milled sampling strategy for δ18O analysis permits a precise estimate of archaeological seasonality, because seasonal freshwater influxes and changes in temperature have dual effects on the δ18O value of the shell. Sclerochronological analysis identifies the timing and duration of growth that is temporally aligned to stable oxygen i…
High-resolution sclerochronological analysis of the bivalve mollusk Saxidomus gigantea from Alaska and British Columbia: techniques for revealing env…
2009
Abstract The butter clam, Saxidomus gigantea , is one of the most commonly recovered bivalves from archaeological shell middens on the Pacific Coast of North America. This study presents the results of the sclerochronology of modern specimens of S. gigantea , collected monthly from Pender Island (British Columbia), and additional modern specimens from the Dundas Islands (BC) and Mink and Little Takli Islands (Alaska). The methods presented can be used as a template to interpret local environmental conditions and increase the precision of seasonality estimates in shellfish using sclerochronology and oxygen isotope analysis. This method can also identify, with a high degree of accuracy, the d…
Prehistoric palaeodemographics and regional land cover change in eastern Iberia
2019
Much attention has been placed on the drivers of vegetation change on the Iberian Peninsula. While climate plays a key role in determining the species pools within different regions and exerts a strong influence on broad vegetation patterning, the role of humans, particularly during prehistory, is less clear. The aim of this paper is to assess the influence of prehistoric population change on shaping vegetation patterns in eastern Iberia and the Balearic Islands between the start of the Neolithic and the late Bronze Age. In all, 3385 radiocarbon dates have been compiled across the study area to provide a palaeodemographic proxy (radiocarbon summed probability distributions (SPDs)). Modelled…
Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers
2016
Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…
Dental microwear texture analysis on extant and extinct sharks : Ante- or post-mortem tooth wear?
2020
Sharks are apex-predators that play an important role in past and present aquatic food webs. However, their diet - especially in extinct species - is often not well constrained. Dental microwear texture analysis (DMTA) has been successfully applied to reconstruct diet and feeding behaviours of different aquatic and terrestrial vertebrates. However, unlike in mammals, food-to-tooth contact in sharks is rather limited because only larger prey is manipulated before swallowing. Together with a fast tooth replacement rate, this reduces wear on individual teeth. Here, we present an explorative study of dental microwear texture on extant and extinct sharks to test whether ante-mortem wear is relat…
Rhinocerotid tooth enamel 18O/16O variability between 23 and 12 Ma in southwestern France.
2006
Abstract The relationship between the oxygen isotope ratio of mammal tooth enamel and that of drinking water was used to reconstruct changes in the Miocene oxygen isotope ratio of rainfall (meteoric water δ 18 O MW ). These, in turn, are related to climatic parameters (temperature, precipitation and evaporation rate). δ 18 O values of rhinocerotid teeth from the Aquitaine Basin (southwestern France) suggest a significant climatic change between 17 and 12 Ma, characterized by cooling together with precipitation increase, in agreement with other terrestrial and oceanic records. To cite this article: I. Bentaleb et al., C. R. Geoscience 338 (2006).
First shark record from the Upper Cretaceous of the Kuril Islands, Far East Russia
2020
Abstract The first find of a Late Cretaceous shark tooth, or of any cartilaginous fish for that matter, from the Kuril Islands in the Russian Far East is recorded as Carcharias sp. (Lamniformes, Carchariidae). The specimen originates from Maastrichtian strata on the island of Shikotan that are assigned to the Malokurilsk Formation. It constitutes an extremely rare find from rocks of this age in the northwest Pacific region. External and internal dental structures have been reconstructed by the use of computed tomography. The vasculature of this lamniform tooth is first modelled by CT scanning and shown under different angles, which allows an assessment of the spatial arrangement of hierarch…
Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian–Early Kimmeridgian) inferred from delta18O of Paris Basin oyster shells.
2008
10 pages; International audience; Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian–Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on nonluminescent parts of shells (n=264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect …
Rich fen development in CE Europe, resilience to climate change and human impact over the last ca. 3500 years
2017
Here, for the first time in SE Poland, we document the long-term development of a rich fen and assess its sensitivity to climate change and human impacts over the last ca. 3500 years. Our results are based on a high-resolution, continuous plant macrofossil remains, mollusc and pollen record, complemented by geochemical, mineral magnetic and physical characterisation, and radiocarbon dating from Bagno Serebryskie rich fen located in SE Poland. Based on the palaeoecological data we distinguished five stages of wet habitat conditions: 5000–3300, 2800–2150, 1600–1100, 750–230, 150–10 cal yr BP and five dry periods at ca. 3300–2800, 2150–1600, 1100–750, 230–150, 10 to − 64 cal yr BP. The pollen …