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Ilhem Bentaleb Cyril Langlois Céline Martin Paula Iacumin Matthieu Carré Pierre-Olivier Antoine Francis Duranthon Issam Moussa Jean-Jacques Jaeger Nicholas Barrett Ron Kandorp 《Comptes Rendus Geoscience》2006,338(3):172-179
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 OMW). These, in turn, are related to climatic parameters (temperature, precipitation and evaporation rate). 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). 相似文献
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We analyzed the isotopic patterns found in the tooth enamel of modern feral horses from Shackleford Banks, North Carolina (USA), which has a temperate climate and supports primarily C4 grasslands. Enamel δ13C values averaged −4.1‰ with a standard deviation (1σ) of 1.7‰, which corresponds to an average diet of 66 ± 12% C4 plants. Our results differ from dietary reconstructions from 1978 to 1981, which found that horses consumed 91% C4 plants. This suggests that horses have increased their consumption of C3 forbs, likely as a result of the removal of cattle, sheep, and goats from the island. Shackleford surface waters had δ18O values that averaged −3.3 ± 0.5‰ and −1.3 ± 1.8‰ on the western and eastern ends of the island, respectively. Tooth enamel samples averaged 27.3 ± 1.5‰ and displayed the same range of δ18O values as surface waters. The variability of both δ18O and the δ13C values among individuals within this population demonstrates that horses from relatively homogenous temperate environments can display a wide range of isotopic values. Given the observed range of isotopic values for modern horses, we suggest that researchers use the mean values of multiple (≥9) equids when attempting to reconstruct average paleodiets and/or paleoenvironmental conditions. 相似文献
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Qingfeng Shao Wei Wang Chenglong Deng Pierre Voinchet Min Lin Antoine Zazzo Eric Douville Jean-Michel Dolo Christophe Falguères Jean-Jacques Bahain 《Quaternary Research》2014
Several Gigantopithecus faunas associated with taxonomically undetermined hominoid fossils and/or stone artifacts are known from southern China. These faunas are particularly important for the study of the evolution of humans and other mammals in Asia. However, the geochronology of the Gigantopithecus faunas remains uncertain. In order to solve this problem, a program of geochronological studies of Gigantopithecus faunas in Guangxi Province was recently initiated. Chuifeng Cave is the first studied site, which yielded 92 Gigantopithecus blacki teeth associated with numerous other mammalian fossils. We carried out combined ESR/U-series dating of fossil teeth and sediment paleomagnetic studies. Our ESR results suggest that the lower layers at this cave can be dated to 1.92 ± 0.14 Ma and the upper layers can be dated to older than 1.38 ± 0.17 Ma. Correlation of the recognized magnetozones to the geomagnetic polarity timescale was achieved by combining magnetostratigraphic, biostratigraphic and ESR data. The combined chronologies establish an Olduvai subchron (1.945–1.778 Ma) for the lowermost Chuifeng Cave sediments. We also analyzed the enamel δ13C values of the Gigantopithecus faunas. Our results show that southern China was dominated by C3 plants during the early Pleistocene and that the Gigantopithecus faunas lived in a woodland-forest ecosystem. 相似文献
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We used analyses of the strontium isotope (87Sr/86Sr) ratios of tooth enamel to reconstruct the migration patterns of fossil mammals collected along the Aucilla River in northern Florida. Specimens date to the late-glacial period and before the last glacial maximum (pre-LGM). Deer and tapir displayed low 87Sr/86Sr ratios that were similar to the ratios of Florida environments, which suggest that these taxa did not migrate long distance outside of the Florida region. Mastodons, mammoths, and equids all displayed a wide range of 87Sr/86Sr ratios. Some individuals in each taxon displayed low 87Sr/86Sr ratios that suggest they ranged locally, while other animals had high 87Sr/86Sr ratios that suggest they migrated long distances (> 150 km) outside of the Florida region. Mastodons were the only taxa from this region that provided enough well-dated specimens to compare changes in migration patterns over time. Pre-LGM mastodons displayed significantly lower 87Sr/86Sr ratios than late-glacial mastodons, which suggests that late-glacial mastodons from Florida migrated longer distances than their earlier counterparts. This change in movement patterns reflects temporal changes in regional vegetation patterns. 相似文献
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Dental histology of periodontal tissues (cementum, periodontal ligament and alveolar bone) has been studied in mammals, crocodylians and some basal tetrapods, but these structures have never been studied in titanosaur sauropods. The goal of this work was to study the structures of dental insertion in Titanosaurs. Like many physiological processes, histological analysis of titanosaur teeth shows hard tissue formation, characterized by a circadian rhythm. From thin sections it was possible to observe microstructures such as incremental lines of von Ebner, dentinal tubules and cross striations, all key to the understanding of developmental tooth dynamics. The structural and histological analyses carried out here on teeth of Late Cretaceous titanosaurs reveals the presence of acellular and cellular cementum, periodontal ligament, and alveolar bone, all structures necessary for a truly thecodont dentition. This is the first time documented for a dinosaur via histological tissue, and is an important finding that will help elucidate aspects of dinosaurian dentition, tooth replacement rate, feeding strategy, metabolism, and general biology. 相似文献
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Accurate decomposition of Electron Spin Resonance (ESR) spectrum is a crucial task to extract compound signal intensities of enamel fragments at different irradiation time, in particular for dose recovery accuracy. While it can be achieved manually, the task is laborious and repetitive. In this paper, we present a new freely available program “ESRfrag” that allows the alignment, merging, and computation of complex angular ESR spectra. This program is an open access web-based code, designed to specifically alleviate the daunting task of working with large amounts of ESR spectra for enamel fragment dating. ESRfrag provides an increased reliability and precision on the results compared to manual calculation by removing operators bias. The program can be freely access through the Geoarchaeology and Archaeometry Research Group website (https://www.garg.org.au/projects). 相似文献
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