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《Plains anthropologist》2013,58(75):67-73
Abstract

Late Plains Woodland burial from a badlands region of western Sioux County, Nebraska produced the nearly complete skeleton of a robust adult male. Burial practices and associated grave goods are typical for the Woodland culture. However, osteological analysis has revealed a pattern of physical characteristics for the human skeleton which shows no real affinity to known Woodland populations to the south and east. Rather, the traits resemble very closely those of the nearly contemporaneous Late Middle Period people of Wyoming, to the immediate west. This lends evidence in support of recent hypotheses regarding the spread of Woodland culture across the central and western Plains.  相似文献   

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《Plains anthropologist》2013,58(50):302-304
Abstract

A pottery type characterized by a cord-roughened surface, punctates and bosses, and incised line decoration from three sites in southwestern Minnesota is typologically similar to Early Woodland pottery from stratified sites in Illinois (Black Sand Incised) and Wisconsin (Dane Incised). Pending further investigations, the indications are that the Minnesota materials are also Early Woodland and that this may be a fairly widely distributed pottery type.  相似文献   

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The evidence for woodmanship in mediaeval Ireland is discussed. Palynological evidence dispels the continuing myth that there were vast mediaeval woods. Nonetheless, place name and documentary sources indicate discrete areas of woodland. At these places underwood was probably managed, livestock sheltered and fattened, berries and nuts gathered and timber felled. A range of historical texts and archaeological excavations support these claims. Woodland was an important aspect of the agricultural landscape and economy.  相似文献   

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Recent Progress in Understanding Early Tetrapods   总被引:2,自引:2,他引:0  
This paper reviews significant discoveries and interpretationsmade for Paleozoic tetrapods over the past twenty-five years.In that span twelve significant, new localities have been found,including the oldest ever at about 370 million years in age.About 60 new genera have been described; five providing importantinsight into the early evolution of land vertebrates. The numberof exceptionally well known taxa with multiple, excellentlypreserved specimens has doubled to eight from four. The veryearliest tetrapods have been discovered to have been polydactylous,the ear region to have had a complicated early evolution andthe specialized tooth type found in Recent amphibians has beenfound in a group of Lower Permian temnospondyl amphibians, indicatingan evolutionary relationship. Perhaps the most significant advancein understanding the evolution of early tetrapods is that thebasal amniote groups have become better characterized and astart has been made in providing a defensible hypothesis fortheir relationships. The ascendancy of cladistics, functionalmorphology and plate tectonics has changed the way paleontologistsview fossils resulting in more defensible phylogenies and behavioraland biogeographical scenarios. These approaches to understandinghave, perhaps, had a more profound impact than any of the newfossil discoveries.  相似文献   

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In vegetated terrestrial ecosystems, carbon in below- and aboveground biomass (BGB, AGB) often constitutes a significant component of total-ecosystem carbon stock. Because carbon in the BGB is difficult to measure, it is often estimated using BGB to AGB ratios. However, this ratio can change markedly along resource gradients, such as water availability, which can lead to substantial errors in BGB estimates. In this study, BGB and AGB sampling was carried out in Eucalyptus populnea-dominated woodland communities of northeast Australia to examine patterns of BGB to AGB ratio and vertical root distribution at three sites along a rainfall gradient (367, 602, and 1,101 mm). At each site, a vegetation inventory was undertaken on five transects (100 × 4 m), and trees representing the E. populnea vegetation structure were harvested and excavated to measure aboveground and coarse-root (diameter of at least 15 mm) biomass. Biomass of fine and small roots (diameter less than 15 mm) at each site was estimated from 40 cores sampled to 1 m depth. The BGB to AGB ratio of E. populnea-dominated woodland plant communities declined from 0.58 at the xeric end to 0.36 at the mesic end of the rainfall gradient. This was due to a marked decline in AGB with increased aridity whereas the BGB was relatively stable. The vertical distribution of fine roots in the top 1 m of soil varied along the rainfall gradient. The mesic sites had more fine-root biomass (FRB) in the upper soil profile and less at depth than the xeric site. Accordingly, at the xeric site, a much larger proportion of FRB was found at depth compared to the mesic sites. The vertical distribution patterns of small roots of the E. populnea woodland plant communities were consistently )-shaped, with the highest biomass occurring at 15–30-cm depth. The potential significance of such a rooting pattern for grass–tree and shrub–tree co-existence in these ecosystems is discussed. Overall, our results revealed marked changes in BGB to AGB ratio of E. populnea woodland communities along a rainfall gradient. Because E. populnea woodlands cover a large area (96 M ha), their contribution to continental-scale carbon sequestration and greenhouse gas emission can be substantial. Use of the rainfall-zone-specific ratios found in this study, in lieu of a single generic ratio for the entire region, will significantly improve estimates of BGB carbon stocks in these woodlands. In the absence of more specific data, our results will also be relevant in other regions with similar vegetation and rainfall gradients (that is, arid and semiarid woodland ecosystems).  相似文献   

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云南海口早寒武世褐藻化石新知   总被引:2,自引:2,他引:2  
徐兆良 《Acta Botanica Sinica》2001,43(10):1072-1076
主要报道了产自云南海口耳材村早寒武世筇竹寺组玉案山段澄江生物群中的褐藻化石-拟点叶藻(Punctariopsis latifolia gen.et sp.nov.)简单拟点叶藻(Punctariopsis simplex gen.etsp.nov.)和古德带藻(Vendotaenia cf.antiqua Gnilovskaya)3种。这些化石丰富了澄江生物群物种的多样性,为研究该群生物爆发性演化提供了新的证据。同时通过对现生褐藻和褐藻化石形态学的比较研究,表明化石属和现代属在系统演化上可能有较密切的亲缘关系,并进一步证明了澄江生物群在云南海口地区发生于一个潮间带和亚潮带的海水环境。  相似文献   

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本文介绍基于原地宇生核素26Al和10Be埋藏测年的基本原理:地表石英矿物与次级宇宙射线发生核反应,生成26Al和10Be,两者之比为6.8∶1。若长期暴露于地表的石英被快速深埋,不再接受宇宙射线照射,已积累的宇生放射性核素将随时间流逝而衰减。因26Al比10Be衰变快约一倍,两者之比也将按指数规律随时间衰减,由此可测定埋藏事件的年代。本文并讨论了这一测年新技术的假设前提和限制其应用的多种因素。试用该法于周口店第1地点第7—10层的结果为770±80ka,支持洞穴方解石质谱铀系测年的结果。26Al/10Be埋藏测年法理化基础坚实,独立于其他测年技术,应用范围正值我国年代研究的盲段,所需样品为广泛分布的石英矿物,应可为我国早期人类演化可信年代系列的建立作出重要贡献。  相似文献   

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The influence of inland water bodies on the global carbon cycle and the great potential for long-term carbon burial in them is an important component of global limnology. We used paleolimnological methods to estimate changes in carbon burial rates through time in a suite of natural lakes in the US state of Iowa which has watersheds that have been heavily modified over the last 150 years. Our results show increasing carbon burial for all lakes in our study as agriculture intensified. Our estimates of carbon burial rates, before land clearance, are similar to the published worldwide averages for nutrient-poor lakes. In nearly all the cases, burial rates increased to very high levels (up to 200 g C m−2 y−1) following agricultural development. These results support the idea that the increased autochthonous and allochthonous carbon flux, related to anthropogenic change, leads to higher rates of carbon burial. Further, these results imply that the fraction of global carbon buried by lakes will be increasingly important in the future if worldwide trends in anthropogenic eutrophication continue.  相似文献   

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Schizophrenia is a severe mental disorder affecting approximately 1% of the world's population. Here, we report the results from a three-stage genomewide screen performed in a study sample from an internal isolate of Finland. An effort was made to identify genes predisposing for schizophrenia that are potentially enriched in this isolate, which has an exceptionally high lifetime risk for this trait. Ancestors of the local families with schizophrenia were traced back to the foundation of the population in the 17th century. This genealogical information was used as the basis for the study strategy, which involved screening for alleles shared among affected individuals originating from common ancestors. We found four chromosomal regions with markers revealing pairwise LOD scores>1.0: 1q32.2-q41 (Z(max)=3.82, dominant affecteds-only model), 4q31 (Z(max)=2. 74, dominant 90%-penetrance model), 9q21 (Z(max)=1.95, dominant 90%-penetrance model), and Xp11.4-p11.3 (Z(max)=2.01, recessive 90%-penetrance model). This finding suggests that there are several putative loci predisposing to schizophrenia, even in this isolate.  相似文献   

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By the end of the 19th century, European whalers had brought the bowhead whale (Balaena mysticetus) in the “Spitsbergen stock” ranging the waters between eastern Greenland and the western Russian Arctic to the verge of extinction. This paper presents observations of this species in Northeast Greenland and in the Greenland Sea between 1940 and 2004. The number of observations has increased in Northeast Greenland since the mid-1980s. Only three observations are known for the period 1940–1979 but during the 1980s, the 1990s and between 2000 and 2004, six, six and eight observations of bowhead whales were made, involving an absolute minimum of three, five and eight to ten different individuals, respectively. It remains uncertain whether this represents an increase in survey effort, an immigration from other areas, a recent recovery of an eastern Greenland relict “tribe” belonging to the Spitsbergen stock, or a combination of these factors.  相似文献   

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