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1.
The Chengjiang fauna has played a pivotal role in our understanding of the origin and diversification of metazoans since its discovery in 1984. To date, this fauna has been documented as consisting of 121 genera with 140 species belonging to 24 phyla[1-27]. The geo- graphic distribution of the Chengjiang fauna has been expanded from Chengjiang County to eastern Yunnan Province including Haikou, Malong, Yiliang, Anning and elsewhere[25-33], with about 20 localities in to- tal[25,33]. Succes…  相似文献   

2.
澄江化石库中川滇虫属化石的新信息   总被引:2,自引:0,他引:2  
目的 对澄江化石库中数量可观的软躯体化石卵形川滇虫(Chuandianella ovata)的形态以及生态进行研究。方法 运用解剖学、形态比较学方法。结果 扩展性描述了该属种动物身体的内部构造;对该属种壳表装饰、尾扇结构等形态描述进行了修正;首次得出卵形川滇虫不属于瓦普塔虾科(Waptiidae)的结论;结合形态、功能及生态之间的联系引出了卵形川滇虫生活的方式及古环境。结论 川滇虫是一种生活于浅海底部的自由游泳者,以植物或浮游生物为食,在进化程度上稍低于瓦普塔虾。  相似文献   

3.
This is a brief report of a new occurrence of eocrinoids from the Early Cambrian Wulongqing Formation in Yunnan, China. The eocrinoids from the Guanshan fauna are among the earliest known eocrinoids. Different from many other Early and Middle Cambrian eocrinoids, the Guanshan eocrinoids are char-acterized by the absence of sutural pores and epispires, the long and spiral brachioles, the extremely long stalk, and the ratio of the length of the stalk versus that of the calyx. The discovery of the eocri-noids from the Guanshan fauna not only provides new information to the investigation of the early evolution of this animal group, but also shed new light on the occurrence and migration of early eocrinoids.  相似文献   

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目的探讨云南早寒武世澄江化石库中翻吻动物的运动和生态习性。方法依据大量蠕虫标本的观察,认为的确有一部分翻吻动物化石为异地埋葬,并列举了一些原地埋葬的证据。结果部分翻吻动物如Tylotites petiolaris,Paraselkirkia 可能为营底上生活而并非全部为底内钻孔生活;报道了部分翻吻动物的密集埋葬现象;发现一些Cricocosmia 虫体表面具有一种未知生物属性的附生物,可能代表了一种外寄生关系;翻吻动物在滇东地区的分布可能受水深控制。结论早寒武世翻吻动物的运动,以及生态习性发生了一定程度的分异。  相似文献   

5.
从先秦文献中分析中国古代宗庙祭祀之礼的具体内涵及其作用,并利用史实资料揭示其中出现的行礼背义现象以及以“孝”之名掩盖逾制、僭越和不孝之实,从而为找出当今社会祖先祭祀中某些不正常现象的根源提供启示。  相似文献   

6.
目的 系统分析滇东泥质基底澄江化石库腕足动物的生活方式.方法 依据澄江化石库丰富的腕足动物资料,论证寒武纪早期泥质基底腕足动物的生活策略.结果 寒武纪早期泥质基底上腕足动物的生活方式主要包括肉茎附着型(pedicle-anchoring or pedicle-attaching)、自由平躺型(free-lying)、假内栖型(qusi-infaunal)和表栖粘附型(cemented epifaunal),肉茎附着型是早寒武世腕足动物生活的最普遍的型式.结论 空间生态分析显示,早寒武世滇东海盆中,腕足动物的分布已经具有一定的空间层次性,不同的腕足类型占据了不同的生态位,形成了比较复杂的空间群落结构.  相似文献   

7.
澄江化石库发现新舌形贝型腕足动物   总被引:1,自引:0,他引:1  
目的 报道澄江化石库中最新发现的舌形贝型腕足动物——海口西山贝(Xianshanella haikouensis gen.et sp.nov.)。方法 运用经典古生物学方法,结合化石解剖、形态比较进行研究。结果 贝体轮廓呈圆形,刚毛长、浓而坚硬,肉茎长而粗大,经鉴定为一新属、新种。结论 形态研究表明它们应属于圆货贝类,但可能的肌肉系统显示这类生物可能与神父贝类相关;结合形态特点和生态特征,认为这类生物并非可能穴居生活,而以肉茎固着海底、营滤食生活。它们的发现丰富了澄江化石库腕足动物的多样性,对于理解早寒武世腕足动物分异有重要意义。  相似文献   

8.
The taxonomy of an early ancestor of Recent Priapulidae, Xiaoheiqingella peculiaris (= Yunnanpriapulus halteroformis Huang et al., 2004) from the Early Cambrian Chengjiang fossil Lagerstaette, is revised. Morphological characters comprise a pair of caudal appendages rather than a single appendage flanking the trunk end and a possible urogenital duct found inside the preanal region. An additional extremely rare fossil priapulid worm, Paratubiluchus bicaudatus gen. nov., sp. nov. is also described herein. Its diagnostic characters are: an introvert bearing 25 longitudinal rows of scalids, a distinct neck region, no annulus on the oval trunk, and a pair of caudal appendages. The proportion of body parts is similar in size to that of loricate larvae of Recent priapulids and larva-formed Palaeopriapulitidae. Taking account of the features of Xiaoheiqingella, bicaudal appendages are considered to be a synapomorphy of Priapulidae and Tubiluchidae. Paratubiluchus gen. nov. is most likely a candidate for the ancestor of the Tubiluchidae; it probably originated from a larva-formed priapulid with 25 rows of scalids, thus representing an intermediate link between the priapulids in mature-form and the priapulids with lorica.  相似文献   

9.
中国祭祖文化的社会功能及现代性   总被引:1,自引:0,他引:1  
作为祭祀文化之一的祭祖行为的内涵不断地丰富发展,所担负的功能也不断延伸,从最初的通过沟通人神关系,最终落实到调节社会人际关系.时至今日,祭祖行为已内化为中国人的一种心理需求和感情依托形式,进而成为一种特殊的文化形态.然而,随着时代的不断发展,祭祖文化既对社会的进步与变革带来了积极影响,也产生了一定的负面作用.对祭祖文化进行剖析,以求在现代社会中找寻祭祖文化积极的传承之路.  相似文献   

10.
Facivermis yunnanicus (Hou & Chen, 1989), from the Early Cambrian Chengjiang Lagerstatte, a worm-like fossil with 5 pairs of tentacles and a perceived shrunken end, has been regarded as related to polychaetes, later it has been variously interpreted as Iobopods, Pentastoma and Iophophorates. Newly discovered complete specimens by the ELI field team show that the taxon has, in addition to the 5 pairs of appendages, a pear-shaped trunk end bearing two or three circles of hooks. Accordingly based on these important morphological characters, reconsideration of its affinities is provided and the taxonomy is remedied herein. Because the five pairs of appendages of Facivermis yunnanicus resemble the appendages of the fore-trunk of Iobopod Miraluolishania (Liu & Shu, 2004), it seems that they are homologous structures. Therefore, the affinities of Facivermis are regarded here as being close to the Iobopods, in addition, the lobe-like appendages of Facivermis are very crucial to exploring the origin of the appendages of Iobopods and arthropods.  相似文献   

11.
The loess-paleosol sequence in China records abundant and valuable information on the global and regional climate changes. Biological record from the loess sequence is the most direct evidence on variation in pattern of paleo-atmospheric circulation and changes in winter and summer monsoon. A new record of climatic instability, which occurred in the Loess Plateau during the late glacial period, is presented. Through the study of terrestrial mollusks from three loess sequences, the authors intend to characterize the biological response process to rapid climate change and to learn the mechanisms driving the instable climate changes and the possible linkage in different regions. The result shows the striking consistent variability in the ratio records of three mollusk sequences of the late glacial, indicating apparent rapid climate fluctuations. Correlation of our three mollusk records with the oxygen isotopic records from Greenland ice cores and foraminifera1 records from the Northeast Pacific Ocean reveals similar instability climate during the late glacial period, which provides us a new thought probing the climate instability observed in the North Atlantic, the North Pacific and the Loess Plateau. The low-level atmospheric circulation in the Northern Hemisphere may be one possible way to link the unstable climate patterns observed in the above three regions.  相似文献   

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Major element concentrations were analyzed on the sediments of a 203.6-m core from the North China Plain near Tianjin. The chemical index of alteration (CIA), Al2O3-(CaO+Na2O)-K2O diagram and elemental ratios, such as Al/K and Ti/Na, were used to reveal information of chemical weathering in the source regions since the late Pliocene. Results show that the fluvial materials in the North China Plain were derived from vast regions, which were in the early Na and Ca removal stage and underwent numerous upper-crustal recycling processes. Proxies of chemical weathering show a decreasing trend, in parallel with the global cooling since the late Pliocene, suggesting a strong role of the global cooing in controlling the continental chemical weathering intensity.  相似文献   

15.
Guo ZT  Ruddiman WF  Hao QZ  Wu HB  Qiao YS  Zhu RX  Peng SZ  Wei JJ  Yuan BY  Liu TS 《Nature》2002,416(6877):159-163
The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic era. But the dating of this transition is uncertain, partly because desert sediments are usually scattered, discontinuous and difficult to date. Here we report nearly continuous aeolian deposits covering the interval from 22 to 6.2 million years ago, on the basis of palaeomagnetic measurements and fossil evidence. A total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish soils. This new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of Asia by the early Miocene epoch, at least 14 million years earlier than previously thought. Regional tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in Asia.  相似文献   

16.
Origin of a gene regulatory mechanism in the evolution of echinoderms   总被引:1,自引:0,他引:1  
A rich diversity of ancient sea urchin lineages survives to the present. These include several advanced orders as well as the cidaroids, which represent the group ancestral to all other sea urchins. Here we show that all advanced groups of sea urchins examined possess in their eggs a class of maternal messenger RNA (mRNA) encoded by the evolutionarily highly conserved alpha-subtype histone genes. The maternal histone mRNAs are unique in their time of accumulation in oogenesis, their localization in the egg nucleus and their delayed timing of translation after fertilization. Cidaroid sea urchins as well as other echinoderm classes, such as starfish and sea cucumbers, possess the genes but do not have maternal alpha-subtype histone mRNAs in their eggs. Thus, although all the echinoderms examined transcribe alpha-subtype histone genes during embryogenesis, the expression of these genes as maternal mRNAs is confined to advanced sea urchins. The fossil record allows us to pinpoint the evolution of this mode of expression of alpha-histone genes to the time of the splitting of advanced sea urchin lineages from the ancestral cidaroids in a radiation which occurred in a relatively brief interval of time approximately 190-200 Myr ago. The origin of a unique gene regulatory mechanism can thus be correlated with a set of macroevolutionary events.  相似文献   

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西北地区湖相浊流沉积   总被引:34,自引:5,他引:34  
通过对各地质时代不同野外及钻井剖面岩相特征的详细研究,认为西北地区的湖相浊流沉积均形成于湖底扇环境,浊积岩具粒序层理、包卷层理、槽模、沟模、锥模、刷模和重荷模以及滑塌褶皱等构造。划分出杂乱砾岩(A1)、具碟状构造的块状砂岩(B1)、块状砂岩(B2)、近基浊积岩(C)、无基浊积岩(D)、不规则互层的砂泥岩(E)、滑塌褶皱层(F)及页岩、硅质岩(G)等岩相。同时,归纳出内扇、中扇及外扇相结合,论述了湖泊相浊流沉积的成因及石油地质意义。  相似文献   

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