The Bivalve Yangtzedonta is not the Brachiopod Xianfengella   总被引：2，自引：0，他引：2  

YU Wen Nanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing  Jiangsu  China 《《地质学报》英文版》2005,79(6):770-776

Abstract The alleged ＂holotype＂of the bivalve Yangtzedonta primitiva Yu.1985 figured by Qian （2001） is a broken and distorted specimen of the brachiopod Xianfengella prima He and Yang, 1982 and not the holotype of Y. primitiva. Qian contends that the oldest recognized monoplacophoran, Maikhanella pristinis （Jiang, 1980）, is neither a monoplacophoran nor the oldest molluscan fossil in the Meishucunian Stage of China. Furthermore, he considers that the oldest bivalve Xianfengoconcha eUiptica Zhang, 1980 is an inarticulate brachiopod, not a mollusc. WatsoneUa yunnanensis （He and Yang, 1982）, is associated with Yangtzedonta primitiva Yu but indicates no evolutionary relationship between the Classes Rostroconchia and Bivalvia in the Lower Cambrian Zhongyicun Member of the Yuhucun Formation. Qian＇s confusion in using non-molluscan fossils to discuss the early evolution of shelled molluscs also confuses the basic concepts of the respective groups.  相似文献   

Fauna and standing crop of freshwater mussels in Poyang Lake, China     

熊六凤  欧阳珊  吴小平 《中国海洋湖沼学报》2012,30(1):124-135

Freshwater mussels are a major component of the zoobenthos and they therefore play an important role in freshwater ecosystems. The community composition and the standing crop of freshwater mussels in Poyang Lake, the largest freshwater lake in China and one of two lakes connected to the Changjiang (Yangtze) River, were investigated from February 2008 to May 2009. Mussels were sampled in hydrologically and geographically distinct sampling areas. A total of 42 species and 13 genera were identified, of which 32 species were endemic to China. Two species, Unio douglasiae and Lamprotula caveata, dominated all sampling areas. The number of genera and species, and the number of species within each genus, differed significantly among sampling areas. Freshwater mussels were very abundant, with an overall density of 0.28 ± 0.22 ind./m2 and biomass of 4.08 ± 3.96 g/m2. Significant variation observed among sampling areas and among genera was probably due to the variety of habitats among the areas sampled and to the adaptability of different freshwater mussels to environments. This study suggests that Poyang Lake and other freshwater lakes in the region are important sites of freshwater mussel biodiversity and conservation.  相似文献   

Biogeographic characteristics of Zhesi brachiopod fauna and reconstruction of tectonopaleogeography of Jiamusi-Mongolia Block     

WANG Chengwen  LI Ning  ZONG Pu 《世界地质(英文版)》2012,15(2):85-96

The Kungurian-Capitanian ( Permian) Zhesi branchiopod fauna is mainly composed of cold-water typed taxa with high diversity and abundance. This fauna is similar with the coeval brachiopod faunas from Timan-Pechora,Svalbard,and Queen Elizabeth Islands of the Boreal Realm,with no real"warm-water"species. Zhesi brachiopod fauna is a cold-water fauna and should be assigned to the Boreal Realm. Considering the paleogeographic characteristics of this fauna and the basic rationale of paleobiogeographic provinces being controlled by latitude-temperate,and that the above areas were located at 50°N 70°N in the global paleoclimate reconstruction map compiled by Boucot et al. ,the paleo-latitude of the southern margin of Jiamusi-Mongolia Block,where developed the Zhesi brachiopod fauna,is suggested ranging from 40°N to 60°N. Zhesi brachiopod fauna is an endemic fauna,containing more than 75% endemic species and self-grouped as a biogeographic province,termed Inner Mongolia Province. These characteristics indicate that this area was closed or semiclosed at that time. On the Jiamusi-Mongolia Block,the Herlen-Jiamusi Old-land as an obvious "continental barrier"hindered the northward migration of the Zhesi brachiopod fauna and the immigration of brachiopod species from other areas. The Tarim plate has collided with the Kazakhstan plate and the western part of South Tianshan-Beishan-Xar Moron Ocean has been closed. At the same time,the western margin of Jiamusi-Mongolia Block was joined with the Tarim plate. The Xar Moron Ocean in south of Jiamusi-Mongolia Block was wide enough and the ocean temperature rose gradually southward,so that it is not suitable for the cold-water brachiopods to survive and thrive on the northern margin of the North China plate. Thus,the ocean with large width and high temperature formed another natural barrier for the southward migration of the cold-water brachiopods.  相似文献   

流动沙地灌丛内外生境中土壤动物群落结构研究   总被引：1，自引：0，他引：1  

刘任涛  赵哈林  赵学勇 《中国沙漠》2013,33(1):167-173

以中国科学院奈曼沙漠化研究站为依托,调查了小叶锦鸡儿灌丛内外生境中土壤动物群落特征及土壤理化特性,分析了灌丛内外生境中土壤动物群落结构的差异性,并探讨了土壤动物对灌丛覆盖流沙地表产生小生境的响应特征。结果发现,共捕获土壤动物30科,优势类群有大赤螨科、等节跳科和虱啮科,常见类群有球角跳科,中型土壤动物占绝对优势。土壤动物密度、类群数和多样性指数灌丛内显著高于灌丛外（p<0.05）;土壤动物群落均匀度和优势度变化趋势相反,但灌丛内外无显著差异性（p>0.05）。调查季节（夏季）灌丛内外小生境的土壤温度、酸碱度及有机碳含量差异是主要影响因素。流动沙地灌丛下生境中土壤动物分布表现出了明显的聚集现象,土壤动物多样性显著增加,表明小叶锦鸡儿灌丛覆盖流动沙地后能够显著改变土壤动物生存的微生境,从而导致土壤动物群落结构发生了深刻变化。而且,由于对灌丛内外微生境的选择性和适应性差异,动物类群产生了不同的响应模式。  相似文献   

A comparative study of fish community in four main estuaries of China southeastern coastal areas and their adjacent waters   总被引：1，自引：0，他引：1  

Liangmin Huang  Yazhi Zhang  Xianshi Jin  Xiujuan Shan 《中国海洋大学学报(英文版)》2010,9(2):169-177

Based on literature and survery data of fish composition collected by bottom trawl investigation from 2006 to 2007 infour main estuaries of China southeastern coastal areas and their adjacent waters,changes of the taxonomic diversity across spatialand temporal scales of fish community were analyzed by taxonomic diversity indices.The results are as follows:a total number of1397 fish species(including some freshwater species),belonging to 2 classes,42 orders,186 families and 593 genera,were collected inthe studied sea areas.The species richness increased with lower latitudes,particularly so with Perciformes.There were 339 fish spe-cies in the Yangtze River Estuary and adjacent waters,belonging to 2 classes,31 orders,101 families and 231 genera.There were 535fish species in the Minjiang River Estuary and adjacent waters,belonging to 2 classes,33 orders,133 families and 323 genera.A totalnumber of 803 fish species were collected in the Jiulongjiang River Estuary and adjacent waters,which belonged to 2 classes,35 orders,155 families and 419 genera.And 1021 fish species which belonged to 2 classes,32 orders,153 families,and 466 genera were collectedin the Pearl River Estuary and adjacent waters.The numbers of orders and families of fish species from the northern to the southern wa-ters first increased and then decreased.The average variation in taxonomic distinctness(Λ+)gradually decreased with lower latitudes inthe four estuaries and adjacent waters.There were no significant differences in the average taxonomic distinctness(△+)among the fourestuaries and adjacent waters,and fish fauna were closely related with each other,and all of them belonged to the same zoogeographicalfauna(Indian-Malaysia fauna).Fish composition in the Minjiang River Estuary and adjacent waters was more similar to that in the Jiu-longjiang River Estuary and adjacent waters among the four estuaries.Compared with the historical data,the average taxonomic dis-tinctness of fish community showed a great decrease in the Minjiang River Estuary and the Jiulongjiang River Estuary and their adjacentwaters.  相似文献   

中国土壤动物生态地理研究进展(英文)   总被引：7，自引：0，他引：7  

殷秀琴  宋博  董炜华  辛未冬  王野乔 《地理学报(英文版)》2010,20(3):333-346

This review summarizes main research findings in soil fauna eco-geography in China in the past 30 years.The subject areas and main results were overviewed including biodiversity and eco-geological distribution of soil fauna communities.Studies of ecological distributions of soil fauna and dynamic ranges in space from tropical,subtropical to temperate regions,and in categories from forest,grassland,desert,wetland,farmland to urban ecosystems,the responses and indications of soil fauna to soil environments.Ef...  相似文献   

康滇地轴南段江川盆地澄江砂岩微量元素地球化学特征及其地质意义     

薛钧月  李巨初  王红军 《华东地质学院学报》2009,32(1):45-51

主要阐述了江川盆地澄江砂岩（Zac）的紫色砂岩与灰色砂岩、铀矿化蚀变岩微量元素及稀土元素地球化学特征。通过判别与对比,澄江砂岩（Zac）物质来源于活动大陆边缘,虽然铀矿化主要分布在灰色砂岩中,但灰色砂岩并不是控制铀矿化的主要因素,在铀矿化时有深部流体物质的影响。微量元素地球化学特征对探索该区砂岩型铀矿化以及寻找不整合面型铀矿床提供了可能,具有重要的指示意义。  相似文献   

北吕宋岛菲律宾活动带蛇绿岩及其上覆浊积岩的放射虫研究新进展     

Keisuke ISHIDA  Shigeyuki SUZUKI  Carla DIMALANTA  Graciano YUMUL JR.  Karlo QUEA?O  Decibel FAUSTINO-ESLAVA  Edanjarlo MARQUEZ  Noelynna RAMOS  Rolando PE?A 《地球学报》2012,33(S1):29-31

The basement of the Philippine Mobile Belt (PMB) is mainly composed of ophiolites that are mostly overlain by Paleogene to Miocene turbidites in central Luzon. To clarify the geological development of the PMB with respect to the initial stage of the arc volcanism (eg. Yumul et al., 2003, 2008; Dimalanta and Yumul, 2003; Suzuki et al., 2011), radiolarian dating was examined in siliceous sediments associated with the ophiolites and turbidites. The samples were collected from sites identified with the Zambales and Montalban ophiolites, basic tuff phyllites in NW Din-galan, and their overlying formations.  相似文献   

中朝古陆的解体与华北、华泰二克拉通的确立   总被引：1，自引：0，他引：1  

王荃 《地质学报》2012,86(10):1553-1568

半个世纪之前,黄汲清和任纪舜等将华北、东北南部以及西北的阿拉善这类凡有前寒武纪结晶基底出露的地区确定为单一的中朝古陆(或准地台).这种观念一直被沿用迄今.近年,构造地层地体的研究发现原称之“中朝古陆”是由华北和华泰两个克拉通构成,计 11个地块或地体.重新厘定的华北克拉通,其范围只限于辽宁省西部和北部、河北省、内蒙古南...  相似文献   

Response of single benthic metrics and multi-metric methods to anthropogenic pressure gradients, in five distinct European coastal and transitional ecosystems   总被引：4，自引：0，他引：4  

Borja A  Barbone E  Basset A  Borgersen G  Brkljacic M  Elliott M  Garmendia JM  Marques JC  Mazik K  Muxika I  Magalhães Neto J  Norling K  Rodríguez JG  Rosati I  Rygg B  Teixeira H  Trayanova A 《Marine pollution bulletin》2011,62(3):499-513

In recent times many benthic indices have been proposed to assess the ecological quality of marine waters worldwide. In this study we compared single metrics and multi-metric methods to assess coastal and transitional benthic status along human pressure gradients in five distinct environments across Europe: Varna bay and lake (Bulgaria), Lesina lagoon (Italy), Mondego estuary (Portugal), Basque coast (Spain) and Oslofjord (Norway). Hence, 13 single metrics (abundance, number of taxa, and several diversity and sensitivity indices) and eight of the most common indices used within the European Water Framework Directive (WFD) for benthic assessment were selected: index of size spectra (ISS), Benthic assessment tool (BAT), Norwegian quality index (NQI), Multivariate AMBI (M-AMBI), Benthic quality index (BQI), (Benthic ecosystem quality index (BEQI), Benthic index based on taxonomic sufficiency (BITS), and infaunal quality index (IQI). Within each system, sampling sites were ordered in an increasing pressure gradient according to a preliminary classification based on professional judgement. The different indices are largely consistent in their response to pressure gradient, except in some particular cases (i.e. BITS, in all cases, or ISS when a low number of individuals is present). Inconsistencies between indicator responses were most pronounced in transitional waters (i.e. IQI, BEQI), highlighting the difficulties of the generic application of indicators to all marine, estuarine and lagoonal environments. However, some of the single (i.e. ecological groups approach, diversity, richness) and multi-metric methods (i.e. BAT, M-AMBI, NQI) were able to detect such gradients both in transitional and coastal environments, being these multi-metric methods more consistent in the detection than single indices. This study highlights the importance of survey design and good reference conditions for some indicators. The agreement observed between different methodologies and their ability to detect quality trends across distinct environments constitutes a promising result for the implementation of the WFD’s monitoring plans. Moreover, these results have management implications, regarding the dangers of misclassification, uncertainty in the assessment, use of conflicting indices, and testing and validation of indices.  相似文献