共查询到20条相似文献，搜索用时 750 毫秒
1.
Andrei V. Sher Jacobo Weinstock Gennady F. Baryshnikov Sergey P. Davydov Gennady G. Boeskorov Vladimir S. Zazhigin Pavel A. Nikolskiy 《Quaternary Science Reviews》2011,30(17-18):2238-2249
For a long time, “spelaeoid” (cave-bear-like) bears, Ursus (Spelearctos) spp., were believed to be almost purely European animals. Their geographic range has recently been extended to the east, in southern Siberia, Transbaikalia, Kirghizia, Mongolia and Korea. Two unexpected new findings, presented here in detail, significantly change existing views on the distribution of cave bears; both were found in North-Eastern Siberia, far beyond the Arctic Circle, more than 1500 km to the north-east of the previously accepted range.One of the fossils is a mandible, found near the town of Cherskiy at 68.73°N, 161.38°E. The analysis of local geology and accompanying mammal fossils suggests that it comes from the Olyorian Fauna (Early to early Middle Pleistocene). Morphologically, the Cherskiy mandible is closest to Ursus savini, a small middle Pleistocene cave bear from the British Cromer Forest-bed Formation, but differs in having a slightly more advanced dentition, and thus it is described as a new subspecies Ursus savini nordostensis. Another newly recognized fossil of the “spelaeoid” bear is an astragalus found at the Oskhordokh site at 67.54°N, 135.67°E, on a large gravel bar on the right bank of the Adycha River. This specimen is attributed to Ursus cf. deningeri.The paper also presents an interesting example of the interaction between classical and “molecular” palaeontology.The new finds significantly change existing ideas on the ecology and evolution of cave bears, some of the most remarkable members of the extinct Pleistocene megafauna. 相似文献
2.
Gennady F. Baryshnikov Andrey Y. Puzachenko 《Boreas: An International Journal of Quaternary Research》2019,48(3):581-604
Univariate and multivariate statistics were applied to analyse the morphometrical variability of 4920 upper cheek teeth (P4, M1 and M2) of cave bears from 123 geographical sites (180 samples) of different Pliocene – Pleistocene ages. The analysed specimens included those belonging to the big cave bears Ursus kudarensis, U. deningeri, U. spelaeus (three subspecies) and U. kanivetz (including U. ingressus), as well as the small cave bear U. rossicus. The information‐theoretical parameters (Shannon entropy and orderliness (Von Foerster, 1960: On self‐organizing systems and their environments. In Self‐Organizing Systems, 31–50. Pergamon Press, London) were used to estimate tooth diversity in different teeth, different taxa and in selected local chrono‐populations. Multivariate allometry coefficients (Klingenberg, 1996: Multivariate allometry. In Advances in Morphometrics, 23‐49. Plenum Press, New York) were used to describe the relationships of different ‘parts’ of a tooth and to compare allometric patterns amongst species or selected local samples. A multivariate analysis showed a significant overlap of the size/shape parameter ranges in deningeroid and spelaeoid bears within morphological spaces. Within the cave bear lineage, the Deninger's bear has the greatest morphological diversity index (entropy) of all the teeth overall, and the lowest diversity is observed in the final taxon of this lineage – U. kanivetz (=ingressus). The P4 and M2 diversity showed multidirectional correlations with elevation above sea level amongst several ‘local’ populations of Late Pleistocene cave bears. The morphological disparities between the studied taxa are in close agreement with the distances in the available schemes of genetic differentiation based on ancient mitochondrial DNA. The split of U. kudarensis and U. deningeri has a good bootstrap support, which corresponds to the hypothesis about their parallel evolution. The small cave bear U. rossicus is placed between U. arctos and U. deningeri. The phylogenetic signal is more pronounced in the variability of teeth in comparison with other skeletal remains of cave bears (cranium, mandible, or metapodial bones). 相似文献
3.
This article addresses the taphonomic issues surrounding artifact-bear associations in Yarimburgaz Cave, northwestern Turkey. Our purpose is to evaluate the circumstances of bone assemblage formation in the Middle Pleistocene deposits of the cave, identifying the agencies responsible for the accumulations and the causes of bone damage before and following deposition. Pleistocene species representation, bone damage, body part representation, and mortality data indicate that cave bear remains in Yarimburgaz are unrelated to hominid use of the same site. None of the observations on the cave bear remains contradicts the expectations developed from modern wildlife accounts of modern bear behavior; these accumulations resulted from mortality normally associated with hibernation over many generations of den use. Nonursid carnivores also played roles in bone collection and/or modification. We conclude that at least three distinct biological processes contributed to the formation of the Middle Pleistocene faunas: hibernating bears, bone-collecting carnivores such as wolves, and hominids in descending order of importance. The Yarimburgaz faunas represent palimpsests or overlays of many short-term depositional events, the close spatial associations of which are explained by slow or uneven sedimentation rates inside the cave. Although occupations by hominids appear to have been ephemeral in nature, hominids ultimately discarded nearly 1700 stone artifacts in Yarimburgaz Cave. The hominids did not discard many ungulate bones in the same circumstances. These observations suggest that hominid foraging efforts focused on resources other than large game while at the cave. © 1996 John Wiley & Sons, Inc. 相似文献
4.
Anneke H. van Heteren Mietje Germonpré 《Boreas: An International Journal of Quaternary Research》2023,52(4):498-506
The Namur area in Belgium is useful to study brown (Ursus arctos) and cave bears (Ursus spelaeus) as the assemblage contains little temporal and no geographical variation. Here, we aim to assess ontogenetic allometry within cave bears, as well as ecomorphological differences between adult brown bears (n = 9), adult cave bears (n = 5) and juvenile cave bears (n = 3). Landmarks for 3D digitization of the mandible were chosen based on the taphonomical damage of the specimens. Extant brown bears and extinct Pleistocene brown and cave bears were digitized with a Microscribe G2. Generalized Procrustes superimposition was performed on the coordinates. Allometry was studied using regression analysis. Principal component analysis (PCA) was conducted to assess ecomorphological differences between the groups. 61% of the shape variance within juvenile and adult cave bears was predicted by size (n = 8, p < 0.01). The juvenile cave bears have relatively deep horizontal rami. In adult cave bears, the horizontal ramus is much narrower dorsoventrally. Juvenile cave bears have a small masseteric fossa and a short coronoid process, whereas both are larger, relative to mandible size, in adult cave bears. This made juvenile cave bears likely less effective masticators than fully grown cave bears. In the PCA, principal component (PC) 1 accounts for 45.0% of the total variance and PC2 accounts for 27.6%. Fossil U. arctos from Namur fall within the 95% confidence interval of modern North American U. arctos on both PCs, but are more similar to cave bears than the average extant brown bear. From the similarity of fossil and modern brown bears, it can be deduced that the diet of fossil brown bears was probably also within the range of their modern North American conspecifics, although they might have been more efficient at masticating plant matter. 相似文献
5.
Alessandro Mondanaro Mirko Di Febbraro Marina Melchionna Francesco Carotenuto Silvia Castiglione Carmela Serio Simone Danisi Lorenzo Rook Jose Alexandre F. Diniz‐Filho Pasquale Raia 《Boreas: An International Journal of Quaternary Research》2019,48(3):605-615
Cave bears (Ursus spelaeus) are an iconic component of the European late Quaternary Ice Age megafauna. Recent demographic analyses based on cave bear mtDNA sequences and refined radiocarbon dating indicate that cave bear population size and genetic diversity started to decline some 50 kilo years ago (kya). Hence, neither the coldest phase of the last glaciation (started some 24 kya), nor the colonization of Europe by Palaeolithic hunters (started some 45 kya) coincides with the beginning of population decline. Here, we reconstructed cave bear climatic niche evolution through time. Then, we performed spatially explicit population viability analyses to assess cave bear demographics through time in response to climatic changes, human effects on bear survival and their combination. We found that climate change was responsible for a 10‐fold decrease in cave bear population size after 40 kya. However, climate change on its own could not explain U. spelaeus extinction at 24 kya. Additional negative effects consistent with human population expansion are required to explain both U. spelaeus' retreat from eastern Europe since 40 kya and its final extinction. 相似文献
6.
G. G. Matishov N. G. Chelintsev Yu. I. Goryaev P. R. Makarevich D. G. Ishkulov 《Doklady Earth Sciences》2014,458(2):1312-1316
This article presents a method of assessment of the amount of polar bears on the basis of data on vessel counts. The results of 32 vessel transect counts in the southern part of the Kara Sea are used as the primary data. They are processed in an original program using separate extrapolation by sectors and summarizing of data of several different counts. In recent years, the calculated amount of bears in the studied region has varied from 3300 to 3100 individuals (3200, on average). The relative statistical error of estimations smoothly decreases from 8 to 7%. The confidence interval of the estimation at statistical error of 7% and probability level of 95% is 2700–3500 individuals. 相似文献
7.
Sur‐les‐Creux rockshelter is located in the Prealps of southwestern Switzerland. The sequence of deposits in the rockshelter is 80 cm thick and consists of weathered gravels in a phosphate‐rich matrix. A few Middle Palaeolithic artifacts and the bones of cave bear (Ursus spelaeus) were recorded in the fill. We present the results of sedimentological, geochemical, and micromorphological analyses of the rockshelter sediment. All analyses suggest an endokarstic origin of the sediments. The alteration cortices of the gravels imply in situ weathering over a long period. The phosphates are essentially biogenic and have an apatitelike nature. Phosphatization and intense mixing of the sediment are attributed to cave bear (digging of lairs, input of excrements, and carcasses). Only rare carnivore coprolites (lynx) were preserved in the cave deposits. © 2004 Wiley Periodicals, Inc. 相似文献
8.
BLAINE W. SCHUBERT STEVEN C. WALLACE 《Boreas: An International Journal of Quaternary Research》2009,38(3):482-492
The Saltville Valley of southwestern Virginia contains an abundance of extinct Late Pleistocene megafauna. Recent excavations in the valley produced two particularly notable discoveries, the remains of a scavenged mammoth ( Mammuthus sp.) and a giant short-faced bear ( Arctodus simus ). The bear is the first carnivoran record from Saltville, and its large dental dimensions, dentary proportions, and exceptionally short-face, evince an exceedingly powerful bite for this individual. Mammoth remains are relatively abundant from Saltville, but the material described here preserves extreme examples of scavenging by carnivores. Based on comparisons with the feeding behavior and bone alteration patterns of extant hyenas, cats, wolves, and bears, we conclude that at least two types of large carnivorans scavenged this mammoth carcass. AMS radiocarbon dates of 14 510 ± 55 14 C yr BP on the Mammuthus and 14 853 ± 55 14 C yr BP on the A. simus demonstrate that they are nearly the same age. Very few direct radiocarbon dates on A. simus have been reported from the contiguous United States. The Saltville A. simus represents the most eastern date for the species, as well as the only date from the Appalachian Highlands. 相似文献
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Mathematical Geosciences - 相似文献
11.
Methodology for geohazard assessment for hydropower projects 总被引：1，自引：0，他引：1
Fjóla G. Sigtryggsdóttir Jónas Th. Snæbjörnsson Lars Grande Ragnar Sigbjörnsson 《Natural Hazards》2015,79(2):1299-1331
12.
Current methods of establishing suitable locations for onsite wastewater treatment systems (OWTS) are inadequate, particularly in light of the numerous cases of onsite system failure and the resulting adverse consequences. The development of a soil suitability framework for assessing soil suitability for OWTS allows a more practical means of assessment. The use of multivariate statistical analysis techniques, including Principal Component Analysis (PCA) and multi-criteria decision aids of PROMETHEE and GAIA, enabled the identification of suitable soils for effluent renovation. The outcome of the multivariate analysis, together with soil permeability and drainage characteristics permitted the establishment of a framework for assessing soil suitability based on three main soil functions: (1) the ability of the soil to provide suitable effluent renovation, (2) the permeability of the soil, and (3) the soils drainage characteristics. The developed framework was subsequently applied to the research area, Gold Coast, Queensland, Australia, and the use of standard scoring functions were utilised to provide a scoring system to signify which soils were more suitable for effluent renovation processes. From the assessment, it was found that Chromosol and Kurosol soils provided the highest level of effluent renovation, closely followed by Ferrosol and Dermosol, Kandosol and Rudosol soil types. Tennosol and Podosol soil types were found to have a significantly lower suitability, with Hydrosol soils proving the least suitable for renovating effluent from OWTS. 相似文献
13.
A new approach for calculating strain for particulate media 总被引：1，自引：0，他引：1
Discrete element modelling is a viable alternative to conventional continuum‐based analysis for analysing problems involving localized deformations of particulate media. However, to aid in the interpretation of the results, it is useful to express the results of discrete element analyses in terms of the continuum parameters of stress and strain. A number of homogenization methods have been proposed to calculate strain in discrete systems; however, two significant limitations of these methods remain. First, none of these methods incorporate particle rotation effects satisfactorily, although significant particle rotation occurs in shear bands in both physical tests and numerical simulations of granular materials. Additionally, observations of the particle displacement fields in shear bands in granular materials indicate that the displacements within the localizations are erratic. Consequently, existing linear, local interpolation approaches produce substantial variations in the strain values calculated in adjacent elements in the region of localization, hindering clear visualization of the strain localization as it evolves. A new method of domain discretization for calculating strain is proposed. This method is capable of capturing particle rotation and employs a non‐local meshfree interpolation procedure capable of smoothing the erratic displacements in strain localizations, which better defines their evolution. The proposed method is validated for problems involving both two and three dimensions. A number of methods are compared with the proposed method and pertinent insights are made. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
14.
湘南地区蕴藏着丰富的锡矿资源,锡及锡多金属矿矿床(点)分布广泛,类型复杂,它们的形成除与花岗质侵入岩体直接相关外,同时还受到区域地层和地质构造等因素的共同制约。通过对锡矿的地质背景、分布特征、矿床特征与矿化规律、矿床成因及找矿信息和标志的研究,把湘南地区锡矿的找矿归纳为:"划带、圈区、寻体、定位"的找矿模式,不仅从宏观上提出了或解决了锡矿找矿方向的问题,而且近几年来的地质找矿工作得到了实践应用,并取得了丰硕的找矿成果。 相似文献
15.
我国海洋生态调查指南编制说明 总被引：1，自引：0，他引：1
海洋生态调查的主要目的是了解海洋生态系统基本的群落结构和生态功能及其重要影响因素,掌握生态系统健康状况,把握其变化趋势。基于生态系统健康理论建立我国海洋生态调查的基本框架体系,编制了我国海洋生态调查指南。根据目前的技术设备、实用方法和经费限制,确定最能反映我国海洋生态系统特征的生态要素和评价内容,并规定了相应的调查和评价方法。与《海洋调查规范海洋生物调查》和《海洋监测规范》比较,该指南具有3个显著特点：①调查要素不仅包括海洋生物和海洋环境等自然要素,还包括人为活动要素,充分考虑我国近海生态系统的高强度开发利用的特点;②从生态系统的结构、功能和压力3个方面建立起海洋生态系统健康评价的核心框架体系;③提出生态压力的量化指标,定量评估人类活动对生态系统的压力。 相似文献
16.
Recent emergency flood situations at European rivers have revealed the demand for better and in-time information for citizens
in flood prone areas about flood development, as well as better coordination of resources and actions during pre-flood phases
and its critical stage. Information and Communication Technology (ICT) has a large potential to improve the situation. Decisions
may be supported by information about resources available at the region and national level, by information about means and
access to critical locations at the prevention as well as the evacuation phases, and by including citizens as well as managers
into one common information and communication process. The paper outlines the potential of ICT for these aspects. 相似文献
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《地学前缘(英文版)》2014,(5):I0001-I0003
正1 AIMANDSCOPE GEOSCINCE FRONTIERS(GSF)is a bi-monthly international journal that publishes in English high quality original research articles and timely reviews in interdisciplinary fields of Earth and Planetary Sciences.GSF aims to bridge innovative,provocative and challenging concepts and models related to various fields of research including petrology and geochemistry in understanding lithospheric architecture and mantle dynamics,global tectonics,economic geology and fuel exploration,geophysics,stratigraphy and paleontology with new insights on correlations and evolution,environmental and engineering geology,astrogeology,among other themes.The article categories 相似文献
19.
Length distributions from sedimentary bodies can be measured in outcrop. A common feature in many outcrops is the occurrence of partially exposed bodies, i.e., sedimentary bodies that are cut by either one or both edges of the outcrop. Ignoring these partials while establishing a length distribution leads to a bias toward the smaller length classes. This is because larger bodies have a larger probability to occur as partials than smaller bodies. We present a new method for estimating the expected complete length for a partially exposed feature, based on the theory of conditional probability. The method is demonstrated and tested on a sandstone outcrop exhibiting over 200 interbedded thin silt/shale streaks. It is shown that the method can significantly enlarge both the size and the representativeness of length distributions. 相似文献
20.
Qualitative geological acceptance criteria and quantitative seismological acceptance criteria for radioactive waste disposals are developed. The background material for the initiation of site selection and for its earthquake hazard assessment is discussed. The recent movements of the Earth's surface as well as the other mechanical properties of geological media, hydrological conditions of geological blocks, their groundwater chemistry, geochemical rheology, petrological analyses of rocks, etc., have to be taken into account. A new comprehensive integrated safety analysis of the final underground disposal of spent nuclear fuel has been underway in the Czech Republic since 1991. In accordance with these seismogeological acceptance criteria regions for building underground final radioactive waste disposals are singled out in the Czech Republic. 相似文献