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11.
Evolution of occlusal shape of the first and second upper molars of Middle–Late Pleistocene collared lemmings (Dicrostonyx,Arvicolinae, Rodentia) in northeast European Russia 下载免费PDF全文
Dmitry Ponomarev Andrey Puzachenko 《Boreas: An International Journal of Quaternary Research》2015,44(4):741-759
An approach combining traditional morphotypical methods, multivariate analysis and informational‐statistical methods was used to study evolutionary changes in the occlusal shape of the first and second upper molars of Recent and Middle–Late Pleistocene Dicrostonyx (32 samples) from localities in northeast European Russia (northeastern Russian Plain, the Timan Ridge and the northern part of the Urals). The evolutionary history is described in terms of morphological evolutionary levels of teeth suggested by Smirnov et al. (1997, Materialy Po Istorii I Sovremennomu Sostojaniju Fauny Severa Zapadnoj Sibiri: Sbornik Nauchnyh Trudov, Chelyabinsk, slightly modified). Based on 14C‐dated samples, levels of molar evolution did not always successively replace each other in time, but rather there were often synchronous populations at any given level. This finding supports the notion of a mosaic pattern of morphotypical diversity and relatively independent, parallel evolution of lemming teeth amongst different populations. Six relatively distinct stages in the evolutionary history of Dicrostonyx from the Pechora (Dnieper) to Recent time have been described, but estimations of their relative ages are often debatable. The rates of change in the M1 and M2 morphotypes and morphological diversity in collared lemmings varied over the entire time interval. The fastest replacement of morphotypes and the highest level of morphological diversity in the study area occurred approximately during the Lateglacial (16–10 cal. ka BP). In the present study, we suggest a new version of evolutionary history of collared lemmings in northeast European Russia, taking into consideration the morphological variability of molars, radiocarbon dates and geological data. Our results provide a more detailed pattern of species evolution in the studied region and specific ages of some localities. 相似文献
12.
Frank Kienast Sebastian Wetterich Svetlana Kuzmina Lutz Schirrmeister Andrei A. Andreev Pavel Tarasov Larisa Nazarova Annette Kossler Larisa Frolova Viktor V. Kunitsky 《Quaternary Science Reviews》2011,30(17-18):2134-2159
Permafrost records, accessible at outcrops along the coast of Oyogos Yar at the Dmitry Laptev Strait, NE-Siberia, provide unique insights into the environmental history of Western Beringia during the Last Interglacial. The remains of terrestrial and freshwater organisms, including plants, coleopterans, chironomids, cladocerans, ostracods and molluscs, have been preserved in the frozen deposits of a shallow paleo-lake and indicate a boreal climate at the present-day arctic mainland coast during the Last Interglacial. Terrestrial beetle and plant remains suggest the former existence of open forest-tundra with larch (Larix dahurica), tree alder (Alnus incana), birch and alder shrubs (Duschekia fruticosa, Betula fruticosa, Betula divaricata, Betula nana), interspersed with patches of steppe and meadows. Consequently, the tree line was shifted to at least 270 km north of its current position. Aquatic organisms, such as chironomids, cladocerans, ostracods, molluscs and hydrophytes, indicate the formation of a shallow lake as the result of thermokarst processes. Steppe plants and beetles suggest low net precipitation. Littoral pioneer plants and chironomids indicate intense lake level fluctuations due to high evaporation. Many of the organisms are thermophilous, indicating a mean air temperature of the warmest month that was greater than 13 °C, which is above the minimum requirements for tree growth. These temperatures are in contrast to the modern values of less than 4 °C in the study area. The terrestrial and freshwater organism remains were found at a coastal exposure that was only 3.5 m above sea level and in a position where they should have been under sea during the Last Interglacial when the global sea level was 6–10 m higher than the current levels. The results suggest that during the last warm stage, the site was inland, and its modern coastal situation is the result of tectonic subsidence. 相似文献
13.
Larisa A. Savelieva Andrei A. Andreev Raphael Gromig Dmitry A. Subetto Grigory B. Fedorov Volker Wennrich Bernd Wagner Martin Melles 《Boreas: An International Journal of Quaternary Research》2019,48(2):349-360
The new pollen record from the upper 12.75 m of a sediment core obtained in Lake Ladoga documents regional vegetation and climate changes in northwestern Russia over the last 13.9 cal. ka. The Lateglacial chronostratigraphy is based on varve chronology, while the Holocene stratigraphy is based on AMS 14C and OSL dates, supported by comparison with regional pollen records. During the Lateglacial (c. 13.9–11.2 cal. ka BP), the Lake Ladoga region experienced several climatic fluctuations as reflected in vegetation changes. Shrub and grass communities dominated between c. 13.9 and 13.2 cal. ka BP. The increase in Picea pollen at c. 13.2 cal. ka BP probably reflects the appearance of spruce in the southern Ladoga region at the beginning of the Allerød interstadial. After c. 12.6 cal. ka BP, the Younger Dryas cooling caused a significant decrease in spruce and increase in Artemisia with other herbs, indicative of tundra‐ and steppe‐like vegetation. A sharp transition from tundra‐steppe habitats to sparse birch forests characterizes the onset of Holocene warming c. 11.2 cal. ka BP. Pine forests dominated in the region from c. 9.0 to 8.1 cal. ka BP. The most favourable climatic conditions for deciduous broad‐leaved taxa existed between c. 8.1 and 5.5 cal. ka BP. Alder experiences an abrupt increase in the local vegetation c. 7.8 cal. ka BP. The decrease in tree pollen taxa (especially Picea) and the increase in herbs (mainly Poaceae) probably reflect human activity during the last 2.2 cal. ka. Pine forests have dominated the region since that time. Secale and other Cerealia pollen as well as ruderal herbs are permanently recorded since c. 0.8 cal. ka BP. 相似文献
14.
Izvestiya, Atmospheric and Oceanic Physics - The mesoscale circulation of waters in the East Sakhalin Current region (the western Sea of Okhotsk) is studied for the period of 1993 to 2014 using... 相似文献
15.
16.
Churkin K. O. Nefedyev Yu. A. Andreev A. O. Demina N. Yu. Kronrod E. V. 《Astronomy Reports》2021,65(7):580-587
Astronomy Reports - One of the priority tasks of modern astronomy is the observation and study of transient celestial processes, which also concerns photoelectric observations of lunar occultations... 相似文献
17.
Mubarakshina R. R. Lapaeva V. V. Kashcheev R. A. Zagretdinov R. V. Nefedyev Y. A. Andreev A. O. 《Astronomy Reports》2021,65(3):224-232
Astronomy Reports - This study is focused on the analysis of data of the long-term latitude observations and the Global Navigation Satellite System (GNSS). The latitude observations include... 相似文献
18.
Rytsk E. Yu. Tolmacheva E. V. Velikoslavinsky S. D. Kuznetsov A. B. Rodionov N. V. Andreev A. A. Fedoseenko A. M. 《Doklady Earth Sciences》2021,496(2):146-150
Doklady Earth Sciences - The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported.... 相似文献
19.
Possible cavitation disintegration of polymineral microparticles placed into a liquid as a result of interaction of particles with collapsed cavitation bubbles is shown for the minerals most abundant in gold ore. The bubbles are generated by shock loading of the liquid heated to the boiling temperature. The possibility of cavitation separation of nano-and microscale monomineral fractions from polymineral microparticles is demonstrated. 相似文献
20.
Many tens of severe earthquake damage patterns were revealed at the ancient city of Ayla. The seismic deformation patterns
are of various types, including systematic tilting of walls, systematic shifting and rotation of wall fragments and individual
stones, arch deformations and joints crossing two or more stones. Features of later repair, supporting walls and secondary
use of building stones suggest that the damage patterns can be explained by two historical devastating earthquakes: (I) revealed
in the constructions built during the late Rashidun period (644–656 A.D.); (II) revealed in the structures restored and/or
built during the Fatimid period (1050–1116 A.D.). The maximum observed intensity of both earthquakes at the studied site was
not less than IX (EMS98 scale). The sources of the seismic events were probably the Dead Sea Transform and Wadi Araba Faults
that cross the site obliquely. The last 1995 Nuweiba earthquake with maximum observed intensity VIII has also left its clear
traces in the excavated ancient Ayla buildings. The severity of the destruction was significantly increased because of site
effects. 相似文献