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1.
The Marattiales is one of the oldest lineages of vascular plants with extensive fossil records dated back to the Carboniferous. Understanding the fossil diversity variation and distribution pattern is helpful for exploring the evolutionary history of this fern group. In this work, the preliminary analysis of diversity change and distribution of the Mesozoic Marattialean fossil records in China are reported covering the Triassic and Jurassic periods based on available published data. In addition, a brief discussion is made regarding to the potential causes for these variation and distribution of this fern group.  相似文献   

2.
1984年以来,我队开展了1:20万莱阳幅区域地质测量的修测工作。为了配合野外的地质工作,我组对莱阳盆地莱阳组的各门类化石进行了采集。在莱阳县团旺镇团旺村西采集到一批鱼化石,它们产于莱阳组的中上部黄绿、灰绿色砂质页岩中。所采鱼化石保存较好的不多,经笔者初步鉴定,多数为狼鳍鱼(Lycoptera),主要是中华狼鳍鱼(Lycoptera sinensis),但是还有一块鱼化石为中华弓鳍鱼属(Sinamia)。这种鱼化石在本区是首次发现。这一新的发现,丰富了本地区的鱼化石种类,同时对中华弓鳍鱼的地理分布有新的补充,有助于对这类鱼化石的进一步研究,而且还为我国华北地区中生代后期地层对比提供了  相似文献   

3.
由热应力引起的热破裂作用是造成恐龙化石破坏的一个重要因素。在太阳照射条件下,由于受热不均匀及日照的长久往复循环作用,使得化石表面发生热破裂作用,导致化石表面产生裂缝,加速了恐龙化石风化。采用模拟实验的方式,主要针对恐龙化石试件的物理力学受力变形特性进行研究。通过有限差分软件FLAC3D进行数值模拟,揭示日光辐射造成的恐龙化石温度差异分布对化石风化的影响。试验结果表明:恐龙化石不同部位的温度差异,是造成化石内部热应力分布不均匀的重要原因,热应力的不均匀性导致化石发生热破裂,加速了化石风化受损,因此化石保存要尽量放在恒温环境下,避免化石温度往复变化。  相似文献   

4.
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   

5.
诸城市恐龙化石资源非常丰富,全市共发现恐龙化石产地30多处,其中典型的化石产地有"库沟化石长廊"、"恐龙涧隆起带"、"臧家庄化石层叠区"和"黄龙沟足迹化石群"。当地政府为了保护这些珍贵的化石资源,采取了许多行之有效的保护措施,但在保护过程中发现仍然存在一些不足之处。该文根据目前保护现状,针对保护中存在的主要问题,进行深入分析查找原因,提出可行性措施。  相似文献   

6.
Qinghai Lake is located in a hydrologically closed basin at the conjunction of SE and SW monsoons and westerlies. Its frequent lake level fluctuations arising from climatic and monsoonal changes have left a series of geological records since the last glaciation. The coarse sediments in Core QD1, the sporopollen assemblage representing steppe, the eolian paleo-sanddunes in the east and southeast banks and the fossil glacial topography all indicated frigid and arid climatic conditions and large scale shrinkage of the lake during the last glacial maximum.  相似文献   

7.
古生物化石是确定地质时代、研究古生态环境以及探索地球演化的重要材料。我国古生物化石资源丰富,一些重要的化石和化石产地是我国乃至世界宝贵的自然遗产。全国古生物化石保护工程研究在充分研究全国古生物化石典型产地资料的基础上,对全国17个古生物化石典型产地的化石属种、保护的重要意义、自然地理、地形地质条件以及保护现状进行详细的总结论述。同时通过对全国73家与古生物化石相关的博物馆的现场调查,摸清了各省拥有和建设古生物化石博物馆的基本情况。根据野外调研和综合分析,对我国古生物化石保护工程类型进行了划分。认为我国现行的古生物化石保护工程可分为化石产地保护工程和化石标本保护工程两大类。分析论述了水、冻融、风化、地形地质条件对化石产地保护工程的影响,以及温度、湿度等对古生物化石标本保护工程的影响;在此基础上提出了我国进行古生物化石重点保护工程的规划部署建议。  相似文献   

8.
恐龙化石对研究地球演化、生物进化、地层对比、地质年代、古环境、古地理、古气候等方面具有重要的科学价值。但恐龙化石发掘后面临着严重的风化问题,许多化石发掘后十几年甚至几年内就迅速遭受风化破坏。为深入研究探索恐龙化石地质遗迹的深层次风化原因和机理,该文采用TM(温度和应力)耦合分析方法,对山东诸城恐龙化石风化规律进行深入分析研究。根据化石与围岩间膨胀的不协调性,探索在温度变化情况下化石与围岩间的相互作用规律及对风化造成的影响。结果揭示了温度作用下化石风化的初步原因和规律,可为化石保护提供参考科学依据。  相似文献   

9.
黔南祥摆组的化石资料稀少且以植物化石为主,在独山县羊凤乡祥摆组中发现了一个海相动物群,主要化石有腕足类、珊瑚类、苔藓虫类、头足类和遗迹化石,其中以腕足类最为丰富.在鉴定分析所发现化石的基础上,结合该动物群所在层位的岩性特征、矿物特征和区域上该时期的沉积特征,采用古生态学分析方法,认为该动物群生存环境为一个淡化潟湖.区域上,该潟湖主要位于平塘县与独山县之间,而构成潟湖与外海的障壁则主要位于摆者至麻尾一线东北,呈北西向延伸;在北部兔场附近祥摆组已演变为以泛滥平原沉积为主.潟湖范围内现今构造形态完整,同时这种局限低能的沉积环境可以形成良好的烃源岩,因此它们在区域上的分布对岩相古地理和油气生储盖组合研究具有重要意义.  相似文献   

10.
本文在自己工作的基础上,结合前人资料,提出了华夏植物地理区一个新的亚区——豫淮亚区,用以概括具有重要特色之位于两淮、徐州、豫西一带的二叠纪植物群区系特征.文中着力刻划了该区具有浓郁地方色彩,极高的属种分异度,保存甚佳之植物群轮廓;划分了三个植物组合,即P|Callipteridium koraiense-Cathaysiopteris whitei-Cordaites schenki组合,P_1~2 Fascipteris spp.-Lobatannularia ensifolia-Gigantonocleaspp.组合,P_1~2 Gigantopteris nicotianaefolia-Lobatannularia multifolia-Psygmorphyllummultipartitum组合.文章还结合二叠纪该区独特的区域构造、古地理、古气候等方面,从不同侧面详塑了豫淮亚区的整体格架.  相似文献   

11.
本文对浙江省化石观赏石的主要类型、时空分布等情况作了简要叙述,并结合国际上化石观赏石的收藏和贸易情况,就浙江省的开发问题提出了一些看法。浙江省的恐龙蛋、鱼、螺、贝、虾及笔石等化石具有地方特色,且有一定的数量。这些化石在西方颇受欢迎,有较多的经营者和收藏者。  相似文献   

12.
在理论分析的基础上,利用试验结果模拟分析单轴压力作用下含裂隙恐龙化石断裂损伤过程。在FLAC3D中采用FISH语言编写了基于体元分析的计算程序,采用弹脆性本构模型,分析了试验过程中恐龙化石的裂纹萌生→扩展→贯通规律和裂隙化石的断裂损伤机制。在单轴压缩作用下,含有裂隙的恐龙化石试件的破坏过程主要分三个阶段:即线性变形阶段、非线性变形阶段和软化阶段,当载荷超过应变峰值强度后,化石内部将生成大量新的诱导裂隙,导致化石内部结构发生剧烈变化。值得注意的是,恐龙化石峰后的强度软化过程非常不稳定,峰值附近的材料力学行为对化石试件内部缺陷的分布十分敏感。试验表明,有裂隙恐龙化石的抗压强度值比无裂隙恐龙化石的抗压强度值小30%,最终的残余抗压强度也略小,在加载应力作用下,相比不含内部裂隙的恐龙化石,内含裂隙的恐龙化石其内部裂隙会迅速大量扩展,加重了恐龙化石的风化程度和破坏速度。  相似文献   

13.
诸城是我国重要的恐龙化石产地之一,化石丰富且保存完好,具有非常重要的科学价值。为保护好这一重要地质遗迹资源,增强化石保护的可行性和有效性,该文从恐龙化石防护材料角度入手,在大量试验基础上,研发制配了以甲基三乙氧基有机硅树脂以及氟碳树脂为主要原料,与纳米SiO_2共混形成的新型复合防护材料。试验结果表明,新型防护材料具有良好的抗紫外线、耐老化性和良好的热稳定性,可作为户外化石保护的优质材料。从恐龙化石保护效果看,涂膜透明性好,可保持化石原貌的真实性,同时能提高化石的防水性,增强耐热性和耐酸碱性。该材料在化石保护中具有良好的推广前景。  相似文献   

14.
Huang  Pingping  Zhao  Feng  Xu  Kuidong 《中国海洋湖沼学报》2021,39(1):208-222
The Yellow Sea Cold Water Mass(YSCWM) is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobentho s diffe rs inside and outside of the YSCWM.However,such a pattern has never been observed in the microbenthic ciliate communities.Therefore,we hypothesized that benthic ciliates followed a similar distribution pattern as meio-and macrobentho s,but this pattern has not been uncovered by morphological methods.We evaluated the diversity and distribution of benthic ciliates at five stations along hydrographic gradients across the YSCWM and adj acent shallow water by using morphology and DNA and complementary DNA(cDNA) high-throughput sequencing of the V4 region of 18 S rRNA gene.Results showed that the diversity of benthic ciliate s detected by DNA(303 OTU s),and the cDNA(611 OTUs) sequencing was much higher than that detected by the morphological method(79 species).Morphological method detected roughly different ciliate communities inside and outside of the YSCWM,but without statistical significance.No clear pattern was obtained by DNA sequencing.In contrast,cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos,which coincided well with the results of the environmental parameter analysis.More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates,most(if not all) of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically.The irrelevant historic DNA greatly influenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution.Our research indicates that the methods used have significant effects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates,as well as the potential for benthic environmental assessments.  相似文献   

15.
The investigation of distribution patterns of species diversity is significant for successful biodiversity conservation. The spatial patterns of vegetation and different life-forms species diversity along an elevation gradient in the middle section of the southern slope of the Tianshan Mountains in Xinjiang, China were explored, using the detrended canonical correspondence analysis(DCCA) and the generalized additive model(GAM) methods based on a field survey of 53 sampling plots. In this work 158 species of seed plants were recorded, including 141 herbaceous, 14 shrub, and 2 tree species, in which the woody plants are very limited. 53 sampling plots were classified into 9 major plant communities. The results indicate that the herb communities were the most sensitive to changes in elevation gradient. The diversity indices of the community as a whole presented bimodal patterns. The peak values for the species diversities were found in the transition region between mountain steppe desert and mountain desert steppe(2,200–2,300m), and in the alpine grassland region(2,900–3,100m), while maximum species diversities were in the areas of intermediate environmental gradient. The main environmental factors on the distribution patterns in plant diversity were the elevation, soil water, total nitrogen, available nitrogen, organic matter, and total salt. The response tendency of the four diversity indices for the whole community to the soil environment was the same as that of the herb layers.  相似文献   

16.
Mechanism on bipolar distribution of Permian brachiopods   总被引:1,自引:1,他引:0  
By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana realm through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.  相似文献   

17.
利用加速度记录分析P波质点的受力状态、P波质点随机震动的概率分布及其偏振现象,结果显示,P波质点随机震动的受力矢量服从三维高斯分布,其概率密度呈椭球状分布,可通过加速度记录的协方差矩阵求出偏振椭球的几何参数,从而求出震中方位角.  相似文献   

18.
The mantis shrimp O ratosquilla oratoria is an ecologically and economically important species in the Western Pacific. In present study, the population genetic structure of O ratosquilla oratoria from the Yellow Sea and East China Sea was examined with mitochondrial DNA control region sequences. In total, 394 samples were collected from 18 locations and 102 haplotypes were obtained. For the Yellow Sea, the overall nucleotide diversity and haplotype diversity were 0.006 9 and 0.946 8, respectively; while across all the East China Sea locations, the overall nucleotide diversity and haplotype diversity were 0.027 94 and 0.979 0, respectively. The results of AMOVA and pairwise F_(ST)(0.145 2, P 0.001) revealed moderate differentiation between the Yellow Sea and East China Sea populations of O. oratoria. However, neither the neighbor-joining tree nor haplotype network showed clades with geographic pattern, which indicated considerable gene flow was existed between the Yellow Sea and East China Sea, and supporting the high larval dispersal ability in this species. Mismatch distribution analysis and neutrality tests suggested that O. oratoria has undergone population expansion event, and the Pleistocene glacial cycles might have an impact on the historical demography of O. oratoria. The genetic information obtained in this study can provide useful information for sustainable improvements for capture fisheries management strategies.  相似文献   

19.
本溪系不是岩石地层单位,也不是年代地层单位或生物地层单位,而是历史形成的一种习惯用法。根据地层单位清理的原则,本溪系一名应废弃,置原太原群下部,一并称太原群。辽东地区太原群下部建山城子组、二里河组两个岩石地层单位;辽东半岛南部建山城子组、三棱山组两个岩石地层单位替代原本溪系。华北地台太原群下部(本溪系)海侵方向,根据地层厚度,生物繁衍、迁移路线,地层的空间展布及海相层分析,海水应由北东太子河流域向南西侵进。  相似文献   

20.
Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not dear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.  相似文献   

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