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1.
Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species,Hardyoides damaensis,Meringaspis damaensis and Rhyssometopus (Rodtrifinis) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi,the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope ) into a deep-water of oxygen-poor setting (basin).  相似文献   

2.
The Middle Jurassic Hangfanggou Formation is well exposed in Shangsanjiao and Xiasanjiao villages area,Baimashi town of Huludao,western Liaoning,China.Recently,abundant fossil plants were collected from the Hangfanggou Formation.One new species,Anomozamites sanjiaocunensis sp.nov.(Bennettitales),is described in this study.This is the first report of the genus Anomozamites from the Haifanggou Formation based upon the leaf morphology and epidermal structures.The discovery of the new species extends significantly the stratigraphic and geographic distribution of Anomozamites in the Middle Jurassic.It also shows that Anomozamites was a common member of Bennettitales once lived in the Middle Jurassic warm temperate region.The new species also improves the knowledge on understanding the leaf morphology,epidermal features and the diversity of Anomozamites during the Middle Jurassic.The epidermal characters of the new species and its associated plants reveal that the plants grew in a warm and moderately humid environment in the warm temperate zone.The presence of some deciduous plants,such as ginkgoaleans,czekanowskialeans and conifers,indicate the climate with seasonal fluctuations in temperature.  相似文献   

3.
A new pterosaur Archaeoistiodactylus linglongtaensis gen.et sp.nov.is erected based on an incomplete skeleton with a partial skull and lower jaw.The new taxon is characterized by circular tooth sockets of anterior mandibular teeth,the anterior teeth of the upper jaw bearing posteriorly directed crowns,a relatively short metacarpus,and wing phalanges 2 and 3 and the tibia subequal in length.It possesses some plesiomorphic characters such as short metacarpals and circular tooth sockets.The pointed jaw tip present in the new taxon indicates that the expanded jaw tips of later istiodactylids are a derived character state,and the new taxon represents the first istiodactylus-like pterosaur found from the pre-Late Jurassic deposits,which provides a key role in our understanding the origin and evolution of the known istiodactylid pterosaurs.Archaeoistiodactylus is regarded as the ancestor form of the known istiodactylid pterosaur.  相似文献   

4.
A new pterosaur Archaeoistiodactylus linglongtaensis gen. et sp. nov. is erected based on an incomplete skeleton with a partial skull and lower jaw. The new taxon is characterized by circular tooth sockets of anterior mandibular teeth,the anterior teeth of the upper jaw bearing posteriorly directed crowns,a relatively short metacarpus,and wing phalanges 2 and 3 and the tibia subequal in length. It possesses some plesiomorphic characters such as short metacarpals and circular tooth sockets. The pointed jaw tip present in the new taxon indicates that the expanded jaw tips of later istiodactylids are a derived character state,and the new taxon represents the first istiodactylus-like pterosaur found from the pre-Late Jurassic deposits,which provides a key role in our understanding the origin and evolution of the known istiodactylid pterosaurs. Archaeoistiodactylus is regarded as the ancestor form of the known istiodactylid pterosaur.  相似文献   

5.
根据华北地层大区下寒武统引用地层单位的特征岩性组合构成及其与鲁中特征岩性组合序列的对比,按照"两灰两红"的沉积格局,建立完整连续的岩石地层单位序列:雨台山组—李官组—余粮村组—馒头组。山西及以西各地的霍山组与馒头组的底部层位相当。  相似文献   

6.
7.
土地覆被变化是影响气候系统的重要因素,在全球气候变化研究中具有重要的研究意义,网格化的历史土地利用数据集广泛应用于各类全球变化模式。本文以民国中期军事地形图为基础数据源,以现代行政区划为底图,重建了该时期湖南洞庭湖地区耕地的空间分布。同时为了与最新的HYDE 3.1数据集进行对比,在此基础上获得空间分辨率为10 km×10 km的耕地数据,结果表明:① 民国中期湖南洞庭湖区总耕地面积约为11 432.01 km 2,占研究区域面积的44%,其中汉寿县、华容县、鼎城区和澧县等地耕地面积分布最多,且以围堤耕地为主。分布相对较少的地区有临澧县、汨罗市、岳阳县,以非围堤耕地为主;② 该时段内洞庭湖区耕地垦殖率较大,最大值超过90%,其中高垦区(垦殖率>40%)范围占研究区面积61%,且主要分布在河湖港汊和冲积平原地貌单元上;中低垦区(<=40%)范围占研究区面积39%,主要分布在环湖丘陵地貌单元上;③ 与HYDE 3.1数据对比发现,单位格网(10 km×10 km)内重建的耕地面积结果误差大于40%的比例为17%,且表现为受河流分布影响为主。湖区相对周围重建结果差异更大,HYDE 3.1数据集重建区域尺度较大,较难考虑到小区域范围的水系分布状况,导致其在湖南洞庭湖区重建精度相对较低。  相似文献   

8.
The problem of wild elephants, or human-elephant conflict (HEC), influences the daily life of local communities and hinders the conservation of wild elephants.The perception and attitudes of local communities who inhabited the frontiers between human activities and wild elephant movement are important to the mitigation of the HEC and conservation of wild elephants. To analyze the perception and attitudes of local communities, the Participatory Rural Appraisal (PRA) was used in the investigation of 423 interviewees from 22 villages in Xishuangbanna from July 2009 to February 2010. The results indicated that local communities had their views on the elephant-related problems. In field survey, we found that 66.5% of interviewees were willing to support, participate in, and assist in the conservation of wild elephants;33.5% of interviewees were opposed or indifferent to such conservation, because their livelihoods and even their lives were endangered by wild elephants. These views and attitudes were influenced by local communities′perception of HEC, education level, gender and self-interest. Therefore, it is necessary to analyze the diverse views among local communities and balance profits and costs in addressing HEC.  相似文献   

9.
Using 10-year (January 1998–October 2007) dataset of Sea-viewing Wide Field-of-view Sensor (SeaWiFS), we extracted the dominant spatial patterns and temporal variations of the chlorophyll distribution in the central western South China Sea (SCS) through Empirical Orthogonal Function (EOF) analysis. The results show that the first EOF mode is characterized by a high chlorophyll concentration zone along the Vietnam coast. We found two peaks in summer (July–August) and in winter (December), respectively, in no...  相似文献   

10.
IntroductionArchaefructus ,theoldestknownangiosperms ,werefoundfromtheUpperJurassicJianshangouFormation (i.e .theformerlowerpartofYi  相似文献   

11.
Androecium of the earliest known flowering plant Archaefructus liaoningensis was found from the Upper Jurassic Jianshangou Formation of western Liaoning, China. The androecium consists of numerous stamens bearing in pair on the reproductive axes below conduplicate carpels. The stamens are composed of a short filament and basifixed anther for each. Monosulcate pollen in situ are found from the anthers. The characters of the androecium reveals that Archaefructus are probably protandrous, and the paired stamens and monosulcate pollen appear to indicate that Archaefructus, as primitive angiosperms,might be derived from extinct seed -ferns during the Older Mesozoic. Archaefructus is considered Late Jurassic in age.  相似文献   

12.
Androecium of the earliest known flowering plant Archaefructus liaoningensis was found from the Upper Jurassic Jianshangou Formation of western Liaoning, China. The androecium consists of numerous stamens bearing in pair on the re-productive axes below conduplicate carpels. The stamens are composed of a short filament and basifixed anther for each. Mo-nosulcate pollen in situ are found from the anthers. The characters of the androecium reveals that Archaefructus are probably protandrous, and the paired stamens and monosulcate pollen appear to indicate that Archaefructus, as primitive angiosperms, might be derived from extinct seed-ferns during the Older Mesozoic. Archaefructus is considered Late Jurassic in age.  相似文献   

13.
An artificial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a (Chl a), total organic matter (TOM), total organic carbon (TOC), and total nitrogen (TN) content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed significantly between the two areas, but the TOM, TOC, and TN were not significantly different. The abundance of crustaceans was significantly different between the two areas, but the abundance and biomass ofpolychaetes, echinoderms, mollusk did not differ significantly. The permutational multivariate analysis of variance (PERMANOVA) revealed that the macrobenthic community differed significantly through time and analysis of similarity multivariate analyses (ANOSIM) revealed that the macrobenthic community differed significantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artificial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artificial oyster shell reefs on macrobenthic communities.  相似文献   

14.
INTRODUCTIONPhytoplaktonhasakeyroleinthemarineecosystemasthebasicpartinthefoodchain ,whichisimportantinformationforassessingproductivitypotentialandfisheryresources.Phytoplanktonalsohasanimportantroleinthecarbonbiogeochemicalcycle,becauseitcanabsorbala…  相似文献   

15.
东海中部夏季鱼类群落结构及其多样性分析   总被引:2,自引:0,他引:2  
根据2008年8月东海区主要渔场重要渔业资源调查资料,分析东海中部鱼类的种类组成、区系特征、多样性等群落结构特征。结果表明:共调查捕获鱼类88种,其中暖水种59种,占67.0%;暖温种29种,占33.0%。相对重要性指数(IRI)值大于500的优势种鱼类共有5种,分别为带鱼、刺鲳、小黄鱼、六斑刺鲀和鳄齿鱼;种类丰富度指数变动范围为0.10~2.31,平均为0.88;Shannon-Wiener多样度指数变动范围为0.01~1.86,平均为0.87;种类均匀度指数变动范围为0.01~0.92,平均为0.41;东海中部夏季鱼类多样性指数与往年相比有下降的趋势。  相似文献   

16.
塔里木盆地寒武系白云岩储层具有年代老、埋深大、成岩作用强烈的特征,原生孔隙几乎被破坏殆尽,有效裂缝的发育程度是决定储层优劣的关键因素。根据岩芯描述、薄片鉴定、FMI成像测井、扫描电镜、阴极发光、电子探针以及流体包裹体分析等研究手段,开展了塔里木盆地北部地区(简称"塔北地区")寒武系白云岩储层的裂缝充填特征及有效性分析。塔北地区整体裂缝发育,天山南地区与塔河地区裂缝在产状、线密度、形态以及充填特征上存在差异。天山南地区裂缝线密度与有效性均低于塔河地区,充填矿物主要为自形白云石与石英,其次为方解石、石膏与黄铁矿。充填白云石分为3期,对应的温度区间分别为70℃~90℃、90℃~110℃及110℃以上,均为地层内的成岩流体成因;充填石英分两期,第一期为黏土矿物转化蚀变形成,第二期可能为热液成因。塔河地区裂缝线密度高,有效性较好,溶蚀作用发育,是有利的勘探地区,其充填物以热液矿物组合形式出现,主要为方解石,其次为石膏、鞍状白云石、黏土矿物、沥青等,重晶石以交代白云石的形式出现。充填方解石分为4期,对应的温度区间分别为70℃~100℃、100℃~130℃、130℃~180℃及180℃以上,前3期充填为不同埋深时期地层内成岩流体成因,最后一期充填为自下部运移而来的高温热液流体成因。  相似文献   

17.
The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes. Organisms on the planet en-countered great challenge and the demise of swamp caused the extinction of arborescent lycopods and the rising of Mesophytic plants accomplished the floral transition from the Paleophytic to Mesophytic vegetation. In order to depict the climatic changes and floral succession in the middle and high latitudes of the North Hemisphere, palynological investigation was engaged, and 40 samples collected from the uppermost of Taerlang Formation, Hongyanchi Formation and Quanzijie Formation in the Tianshan Town, Turpan-Hami Basin, eastern Xinjiang, China. The result shows that the palynoflora in the studied area is composed of 50 species of 33 genera, domi-nated by disaccites and striatiti gymnosperm pollen, and characterized by diverse Protohaploxypinus, Hamia-pollenites, Alisporites and Klausipollenites. It is quite similar to those Middle and Late Permian palynological as-semblages reported in the Dalongkou section and other localities in southern margin of Junggar Basin, and aged at Middle and Late Permian. The diversity of typical Angara and sub-Angara pollen, such as Falcisporites, Alisporites, Protohaploxypinus, Vittatina, Lunatisporites, Hamiapollenites, etc. indicates that the studied palyno-flora belonged to the sub-Angara phytoprovince, while the presence of Lueckisporites virkkiae implied Euramerica pollen intruded northward sometimes. The paleoclimate of the studied area might be warm and humid with fluc-tuated dry seasons during the late Guadalupian and early Lopingian time.  相似文献   

18.
Weekly phytoplankton samples were taken from western Hong Kong (Lamma) from Jan. 1997 to Dec. 1999 and from Port Shelter in Eastern Hong Kong from January 1998 to December 1999. During that time diatom blooms occurred repeatedly at both sites but never in synchrony. One species would bloom at one site and then weeks later it or another species would bloom at the other site; while the 1998 red tide of the mucus producing dinoflagellateGymnodinium mikimotoi occurred at both sites. It first occurred at the Port Shelter site in March and did not appear at the Lamma site until April. With the single exception of this species, no other dinoflagellate reached bloom concentrations at the Lamma site. In addition, dinoflagellate abundance at the Lamma site was significantly lower (P<0.05) than that at the Port Shelter site. This was correlated with a significantly higher turbidity (i. e. low Secchi transparency) and higher turbulence (stronger currents) at the Lamma site. Annual variation in surface temperature correlated with total surface phytoplankton abundance at both our sample sites. Phytoplankton abundance increased in spring as water temperatures warmed. In fall, as surface water temperatures began to decline and the monsoon rains became less frequent there was a reduction in phytoplankton abundance associated with the reduction in temperature and light. Because so many variables co-occur with temperature (e. g. the amount of rainfall light intensity and light duration etc.) it is not possible to cite temperature as the causal factor associated weth controlling phytoplankton abundance at our two sample sites. Our data support the rather controversial notion that percentage-wise, there are relatively more harmful bloom forming species in nutrient-rich coastal waters than there are in the world's oceans. 16% of the dinoflagellate species and 10.3% of the diatom species observed at our two sample sites were classed as harmful. These percentages were higher than those cited by Sournia (1995) for the worlds oceans (9.6% and 6.8% respectively). This raises the possibility that there are relatively more toxic species in the nutrient-rich coastal waters of the world than there are in the mid ocean nutrient-poor areas of the world. Some reasons for this are briefly discussed.  相似文献   

19.
Sargassum muticum is one of the most abundant and conspicuous native macroalgae species on the northern coasts of China. It often forms large-scale seaweed beds in subtidal zones. This investigation was designed to understand the intraspecific genetic relationships of this alga based on samples collected from four northern coastal sites of China, and to evaluate gamete release and growth capacity in laboratory conditions. The nuclear internal transcribed spacer 2 (ITS2) sequences of 16 samples from four locations were identical. Based on cox3 gene and partial rbcLS operon sequences, intraspecific genetic variability was detected with three and two ribotypes, respectively. Temperature, not irradiance, was shown to significantly affect gamete release and fertilization. Elevated temperature and irradiance enhanced the growth of germlings and vegetative branchlets. Maximum growth rate of germlings was detected at 18-24℃and an irradiance of 60-100 μmol photons/(m^2.s). Under ambient conditions (12-25℃ and 60-125 gmol photons/ (m2.s)), relative growth rate of young branchlets could reach 7.5%/d.  相似文献   

20.
The composition and distribution of benthic, periphytic and planktonic rotifers in different habitats in Krottensee were investigated. Sixty-five rotifer taxa were identified, their relative abundance estimated. Classification of the data set by cluster analysis allowed the recognition of distinct habitat groups confined to acid bog ponds, macrophytes, sediments and open water. Five groups of rotifer taxa were identified on the basis of their habitat preferences and the occurrence of the taxa. Highest diversities were found on macrophytes and in acid bog ponds.  相似文献   

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