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Abstract. The reef‐dwelling oyster Dendrostrea frons occupied only a small proportion of space in coral reefs of the Quirimba Archipelago, Mozambique, but supported a disproportionately high variety of taxa. Assemblages on primary (substratum), secondary (dead coral heads) and ephemeral secondary space (D. frons shells) of similar area were compared across 5 depths (5, 10, 15, 20 and 25 m) and at four taxonomic levels (species, genus, class and phylum). Differences between the taxonomic richness of each type of space differed with both taxonomic level considered and depth. Of the three categories of space considered, ephemeral secondary space had the most taxa at all levels with the maximum at 10 – 15 m. Despite being small in space and time, animal externa, such as shells of D. frons, may provide important niches for particular organisms at many taxonomic levels.  相似文献   
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池养条件下军曹鱼仔鱼的消化道内容物   总被引:1,自引:0,他引:1  
采用光镜解剖观察的方法对池塘培育的1~20日龄军曹鱼仔鱼消化道内容物的种类、数量和大小进行研究。结果显示:军曹鱼仔鱼于2日龄开口,主要摄食桡足类无节幼体和桡足幼体及枝角类;在2~20日龄阶段,桡足类在军曹鱼仔鱼食谱中占据主要成分;从13日龄开始摄食虾、蟹类幼体等大型浮游动物,两个阶段的食物选择性指数存在显著差异。  相似文献   
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A new long-necked sauropod dinosaur, Yunmenglong ruyangensis gen. et sp. nov., is erected on the basis of an incomplete skeleton from the late Early Cretaceous Haoling Formation of the Ruyang Basin, Henan Province. The characters of the anterior cervical vertebrae, the shape of the neural canal of the dorsal vertebra and the ball-shaped distal end of the neural spine of caudal vertebrae with coarse surfaces differ from other long-necked sauropod dinosaurs. The new genus has characters in common with both Euhelopus and Erketu; it represents the first long-necked sauropod dinosaur recorded from central China to date. The rod-like, well-developed epipophyses and the pleurocoels on the cervical vertebrae indicate that it may be close to Euhelopus, an observation also confirmed by a phylogenetic analysis, which shows that Erketu, Yunmenglong and Qiaowanlong form a clade, and are more derived than Euhelopus.  相似文献   
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Oxytrichidaes. l.ciliates usually have 18 frontal-ventral-transverse cirri which are clustered to six distinct groups usu-ally originating from six longitudinal primordia segregating 1, 3, 3, 3, 4, 4 c...  相似文献   
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池养条件下军曹鱼仔鱼的消化道内容物   总被引:2,自引:0,他引:2  
采用光镜解剖观察的方法对池塘培育的1-20日龄军曹鱼仔鱼消化道内容物的种类、数量和大小进行研究。结果显示:军曹鱼仔鱼于2日龄开口,主要摄食桡足类无节幼体和桡足幼体及枝角类;在2~20日龄阶段,桡足类在军曹鱼仔鱼食谱中占据主要成分;从13日龄开始摄食虾、蟹类幼体等大型浮游动物,两个阶段的食物选择性指数存在显著差异。  相似文献   
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Abstract: The close affinity between Edmontosaurus and Shantungosaurus is corroborated on the basis of the following shared features: an occipital condyle deflected strongly posteroventrally; a posterodorsally reflected, lip-shaped oral margin of the premaxilla, with a deep, oval concavity at the anteromedial corner of the bone; a well-demarcated posterodorsal margin of the deeply excavated circumnarial fossa formed by a prominent arched ridge along the entire posterior half of the lateroventral border of the nasal; an anteroposteriorly broad jugal process of the postorbital; a strongly concave dorsal surface of the paired frontals; seven teeth per alveolus in the middle of the dentary tooth row; and a circular distal blade of the pubis that is much more expanded ventrally than dorsally. A revised phylogenetic analysis of Hadrosauroidea recovers a sister taxon relationship between Edmontosaurus and Shantungosaurus. Kerberosaurus is recovered as the sister taxon to the clade formed exclusively by these two genera. The clade Edmontosaurini could be defined as the least inclusive clade containing Kerberosaurus and Edmontosaurus, which is currently composed of the genera Kerberosaurus, Edmontosaurus, and Shantungosaurus. Zhuchengosaurus and Huaxiaosaurus, both from the Upper Cretaceous Wangshi Group in Zhucheng, are interpreted as junior synonyms of Shantungosaurus. Kundurosaurus is likewise considered a junior synonym of Kerberosaurus. The strict consensus tree together with biogeographic information indicates that the clade Edmontosaurini originated in Asia and subsequently dispersed into North America.  相似文献   
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<正>Juraperla grandis sp.nov.(Grylloblattida:Juraperlidae) is described from the Daohugou locality (Middle Jurassic,China).Its wing venation is very similar to that of Juraperla daohugouensis Huang and Nel,2007 (Grylloblattida:Juraperlidae),in the particular occurrence of a supplementary longitudinal vein in the area between the anterior wing margin and ScP.The larger size of the new specimen,the lower number of CuA1 branches,and the occurrence of two rows of cells between MP and CuA in forewings justify the erection of a new species,J.grandis sp.nov..The material also preserved hind wing and body structures,described for the first time in Juraperlidae.  相似文献   
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石炭系全球界线层型研究进展   总被引:11,自引:2,他引:9  
早石炭世晚期开始的全球大规模构造运动和冈瓦纳大陆的冰川,为石炭系的地层划分和对比带来了困难。通过国际石炭系分会的努力,近年来石炭系各阶的界线层型研究取得了显著的进展。维宪阶已有了古生物学界线定义,即有孔虫Eoparastaffella simplex的首现,其余各阶也有了意向性的界线定义,它们均以牙形刺作为主导化石类群。其中,谢尔普霍夫阶以L ochriea ziegleri的首现为底界;莫斯科阶以Idiognathoides postsulcatus或Declinognathodus donetzianus的首现为底界;卡西莫夫阶的底界为Idiognathodus sagittalis的首现层位;格舍尔阶的底界是Idiognathodus simulator的首现层位  相似文献   
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