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BARBARA WOHLFARTH HELENA ALEXANDERSON LINDA AMPEL OLE BENNIKE STEFAN ENGELS TIMOTHY JOHNSEN JAN LUNDQVIST PAULA REIMER 《Boreas: An International Journal of Quaternary Research》2011,40(2):211-230
Wohlfarth, B., Alexanderson, H., Ampel, L., Bennike, O., Engels, S., Johnsen, T., Lundqvist, J. & Reimer, P. 2010: Pilgrimstad revisited – a multi‐proxy reconstruction of Early/Middle Weichselian climate and environment at a key site in central Sweden. Boreas, 10.1111/j.1502‐3885.2010.00192.x. ISSN 0300‐9483. The site Pilgrimstad in central Sweden has often been cited as a key locality for discussions of ice‐free/ice‐covered intervals during the Early and Middle Weichselian. Multi‐proxy investigations of a recently excavated section at Pilgrimstad now provide a revised picture of the climatic and environmental development between ～80 and 36 ka ago. The combination of sedimentology, geochemistry, OSL and 14C dating, and macrofossil, siliceous microfossil and chironomid analyses shows: (i) a lower succession of glaciofluvial/fluvial, lacustrine and glaciolacustrine sediments; (ii) an upper lacustrine sediment sequence; and (iii) Last Glacial Maximum till cover. Microfossils in the upper lacustrine sediments are initially characteristic for oligo‐ to mesotrophic lakes, and macrofossils indicate arctic/sub‐arctic environments and mean July temperatures >8 °C. These conditions were, however, followed by a return to a low‐nutrient lake and a cold and dry climate. The sequence contains several hiatuses, as shown by the often sharp contacts between individual units, which suggests that ice‐free intervals alternated with possible ice advances during certain parts of the Early and Middle Weichselian. 相似文献
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The start of the Upper Würmian in the Alps was marked by massive fluvioglacial aggradation prior to the arrival of the Central Alpine glaciers. In 1984, the Subcommission on European Quaternary Stratigraphy defined the clay pit of Baumkirchen (in the foreland of the Inn Valley, Austria) as the stratotype for the Middle to Upper Würmian boundary in the Alps. Key for the selection of this site was its radiocarbon chronology, which still ranks among the most important datasets of this time interval in the Alps. In this study we re‐sampled all available original plant specimens and established an accelerator mass spectrometry chronology which supersedes the published 40‐year‐old chronology. The new data show a much smaller scatter and yielded slightly older conventional radiocarbon dates clustering at ca. 31 14C ka BP. When calibrated using INTCAL13 the new data suggest that the sampled interval of 653–681 m in the clay pit was deposited 34–36 cal ka BP. Using two new radiocarbon dates of bone fragments found in the fluvioglacial gravel above the banded clays allows us to constrain the timing of the marked change from lacustrine to fluvioglacial sedimentation to ca. 32–33 cal ka BP, which suggests a possible link to the Heinrich 3 event in the North Atlantic. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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PAULA F. CAMPOS ESKE WILLERSLEV JIM I. MEAD MICHAEL HOFREITER M. THOMAS P. GILBERT 《Boreas: An International Journal of Quaternary Research》2010,39(1):18-23
Campos, P. F., Willerslev, E., Mead, J. I., Hofreiter, M. & Gilbert, M. T. P. 2009: Molecular identification of the extinct mountain goat, Oreamnos harringtoni (Bovidae). Boreas , 10.1111/j.1502-3885.2009.00111.x. ISSN 0300-9483.
Harrington's mountain goat ( Oreamnos harringtoni ), an extinct North American herbivore, is one of the least known mammals of the Pleistocene. Fossil specimens are predominantly known from dry cave localities throughout the arid American west – the Grand Canyon, Colorado Plateau, Nevada and Mexico. Morphological analysis of the recovered fossils suggests a close phylogenetic relationship between Harrington's mountain goat and the extant mountain goats from the American northwest ( Oreamnos americanus ). However, the degree of genetic similarity between the two species, and their overall placement within the Caprinae, is not clear. In this study, we recovered and sequenced the first DNA fragments from O. harringtoni in order to investigate these relationships. Genetic analysis further supports the morphological hypothesis that O. harringtoni and O. americanus are two distinct species. 相似文献
Harrington's mountain goat ( Oreamnos harringtoni ), an extinct North American herbivore, is one of the least known mammals of the Pleistocene. Fossil specimens are predominantly known from dry cave localities throughout the arid American west – the Grand Canyon, Colorado Plateau, Nevada and Mexico. Morphological analysis of the recovered fossils suggests a close phylogenetic relationship between Harrington's mountain goat and the extant mountain goats from the American northwest ( Oreamnos americanus ). However, the degree of genetic similarity between the two species, and their overall placement within the Caprinae, is not clear. In this study, we recovered and sequenced the first DNA fragments from O. harringtoni in order to investigate these relationships. Genetic analysis further supports the morphological hypothesis that O. harringtoni and O. americanus are two distinct species. 相似文献
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Marcelo Leandro BUENO Vanessa Leite REZENDE Luiza Fonseca A.DE PAULA Joo Augusto Alves MEIRA-NETO José Roberto Rodrigues PINTO Andreza Viana NERI Vanessa PONTARA 《山地科学学报》2021,(5):1192-1207
The campo rupestre sensu lato is a vegetation type that occurs in South American mountains, supports a distinctive flora characterized by high rates of endemism, high herbaceous species richness and often-neglected but also species-rich of the arboreal stratum. We aimed to investigate how environmental factors and elevation are associated with the distribution and diversity of woody species in different rupestrian vegetation types across South America. Using a database of 2,049 woody species from 185 sites across four vegetation types within the campo rupestre, we assessed how the vegetation types were grouped according to their floristic composition and number of shared indicator species, as well as by using different beta diversity indices. The most important variables from a set of 27 variables(e.g. altitude, geo-edaphic and climatic) explaining species distribution were identified using redundancy analysis(RDA) and variation partitioning methods. The distribution of vegetation types was related to both environmental and spatial fractions, with a set of 17 variables retained(e.g. rockiness, grass cover and temperature seasonality as the most important variables). There was an association between the floristic composition of each vegetation type and the elevation range. Although the identified vegetation types are floristically related, they are distinguished by exclusive and habitat-specialist woody species. This uniqueness of vegetation types should be considered in terms of complementarity for the conservation of campos rupestres. 相似文献
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THOMAS O. REIMER 《Sedimentology》1971,17(1-2):125-128
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