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1.
论四射珊瑚包珊瑚科(AmplexidaeChapman,1893)的分类   总被引:7,自引:4,他引:3  
讨论了包珊来龙去脉 科(AmplexidaeChapman1893)的分类。把包珊瑚型隔型限于仅在外端连续,向轴部变薄呈短而低的脊状,纵向呈下连续的着生于横板之上。包珊瑚型隔壁的微细构造以层状骨骼为主,其轴部有时可出现非晶榍型纤状之骨骼,包括晶粒和短轴晶柱。  相似文献   

2.
Maikottia属骨骼微细构造及其分类   总被引:1,自引:1,他引:0  
陈建强 《古生物学报》1997,36(4):446-452
Maikottia Laurusevich,1967属是泡沫珊瑚目中较特殊的类型,呈多角块状复体。经电镜研究表明,其骨骼微细构造以晶片型层状骨骼为主,隔壁刺由复式杆晶榍组成,层状骨骼包绕隔壁刺,在隔壁刺内包绕和联结单杆晶榍。体壁和横板均由层状骨骼组成。本属的纤状骨骼属较原始简单类型-晶粒和短轴晶柱,它组成复式杆晶榍内单杆晶榍的轴带,并呈分散状排列。根据该属为泡沫珊瑚类型隔壁及复式杆晶榍,将其归入泡  相似文献   

3.
迄今只报道于我国的梁山珊瑚Liangshanophyllum, 以复中柱较小且简单、横板带宽、横板多水平或稍倾的特征区别于卫根珊瑚Waagenophyllum。本文对两属各种的复中柱大小(占体径比值)进行数据统计和差异性分析, 结果表明在这一特征上, 两属没有显著差异; 定性分析复中柱简繁、横板带宽窄和水平横板发育程度,表明这些特征没有高于种一级的分类意义。结合其他的相关研究成果, 建议废除Liangshanophyllum一属(亚属)。  相似文献   

4.
对Charactophylum作了全面的回顾整理,记述了本属的骨骼构造,在此基础上讨论了其定义范围和时空分布及有关的分类问题。Charactophylum的隔壁为板状隔壁而非包珊瑚型隔壁,由波状弯曲的单列单晶榍组成,单晶榍整体呈半扇形排列而非扇形排列,隔壁光滑或发育微弱的榍凸(carinae)而无典型的横耙状榍凸(yardarmcarinae),鳞板半扇形排列而不是扇形排列。本属分布仅限于北美和华北的晚泥盆世早期。Charactophylum隔壁中单晶榍由放射状排列的不规则短轴晶柱和晶针组成,横列构造鳞板和横板均由晶板型层状骨骼组成。本属骨骼微细构造的重要特征具有奥陶志留纪与石炭二叠纪四射珊瑚之间的过渡性质。表明四射珊瑚骨骼微细构造演化趋向稳定,是追索演化的重要线索,在较高级别的分类中具有重要意义  相似文献   

5.
文采尔珊瑚(Wentzelella)是我国南方、日本、苏联、新西兰、印度、伊朗、伊拉克、意大利、德国和阿尔卑斯山区等地早二迭世地层内常见的一类珊瑚化石。1927年,Grabau创建了这个属,并指定Lonsdaleia salinaria Waagen et Wentzel 为属型。他给予的定义是:“复体,柱状个体,隔壁始端直抵外壁,边缘未发育成像Lonsdaleia 属的泡沫带,复中柱呈朗士德珊瑚型”。Wentzelella 正式公诸于世,则见于黄汲清的论文中。自Grabau 建立这一个属以来,古生物学家列入Wentzelella 属的种和变种,据笔者所知,计有32个;但  相似文献   

6.
对Charactophyllum作了全面的回顾整理,记述了本属的骨骼构造,在此基础上讨论了其定义范围和时空分布及有关的分类问题。Charactophyllum的隔壁为板状隔壁而非包珊瑚型隔壁,由波状弯曲的单列单晶榍组成,单晶榍整体呈半扇形排列,隔壁光滑或发育微弱的榍凸(carinae)而无典型的横耙状榍凸(yardarm carinae),鳞板半扇形排列而不是扉形排列。本属分布仅限于北美和华北的晚  相似文献   

7.
首次描述西藏境内一类中生代非对称的珊瑚化石Paralveolites gen.nov.(新属),产自西藏西部革吉下白垩统。此属的特征是个体没有中生代石珊瑚类个体固有的六射对称性,但却有近似古生代床板珊瑚槽珊瑚(Alveolites)个体半月形截面的外貌。新建一个刺毛海绵新属Homochaetetes gen.nov.,该属的特征是有一列伸入管体轴部的隔壁。另外新建立一刺丝胞动物亚门中分类位置不明的新属Eupseudomillestroma gen.nov.,用以区别只有棱柱状管体而无圆柱状管体的属Pseudomillestroma Deng,1982。  相似文献   

8.
石轴珊瑚Axolithophyllum的一个畸形种   总被引:1,自引:1,他引:0  
1953年,在研究苏联顿涅茨盆地的中、晚石炭世的珊瑚动物群时,在中石炭世L层和晚石炭世的层N以及层O中,发现一类外形常呈蘑菇状的单体珊瑚,他将此类化石定名为石轴珊瑚(Axolithophyllum)。给予的定义为:“单体珊瑚,阔锥状,在萼部中央有一个坚实的轴部构造。在青年期,轴部构造呈简单的圆形和板状;在成年期,轴部构造渐趋复什,中  相似文献   

9.
论小石柱珊瑚类(Lithostrotionelloid)   总被引:1,自引:1,他引:0  
王志根 《古生物学报》1989,28(4):522-545
一、前言在石炭、二叠纪地层中含有一类由多角柱状或圆柱状个体所组成的块状或丛状复体珊瑚,它们具有郎士德型鳞板带和轴部构造,过去人们常将它们鉴定为Lithostrotionella Yabe et Hayasaka,1915。实际上,这类珊瑚包括Stelechophyllum,Aulostylus,Acrocyathus,Petalaxis,Huanglongophyllum,Thysanophyllum,Actinocyathus,Lonsdaleia,Kleopatrina(Porfirievella)。在广西南丹晚石炭世早期Profusulinella带下部地层中盛产lithostrotionelloid珊瑚,经鉴定共有5属24种(及亚种),它们是Acrocya-  相似文献   

10.
通过发育解剖学研究表明,麻花秦艽根的初生结构正常,初生木质部四原型。次生生长的早期阶段也是正常的。在以后的次生生长过程中,由于木质部柱局部区域外的维管形成层向内衍生的细胞分化成木薄壁组织细胞的数量多于导管,从而在木质部内形成薄壁组织细胞区域,并且由于此区域内细胞的增殖,将木质部分成两部分。以后韧皮部也随之分开,从而中柱被分成两个独立的裂分中柱。以后,每个裂分中柱又产生各自的周皮,进而使主根分裂成两个支根。每个支根也可以同样方式分裂产生许多支根。  相似文献   

11.
The relative importance of prezygotic mechanisms of gametophytic competition and selection are often unclear due to an absence of observations on the gynoecium and pollen tube growth in vivo. We used LM, SEM, and TEM to study the structure of the gynoecium and the path of pollen tube growth in Raphanus raphanistrum, a sporophytically self-incompatible annual. Wild radish has a papillate stigma and a solid style. A septum, which is characteristic of cruciferous gynoecia, is present in the ovary. After germination on the stigma, pollen tubes grow in the secretion of the transmitting tract of the style. The stylar secretion stains positive for acidic polysaccharides and insoluble carbohydrates, and negative for lipids and protein. In the ovary, the transmitting tissue is contained inside the septum. The secretion in the ovary stains positive only for acidic polysaccharides. Pollen tubes travel inside the septum as they enter the ovary and must exit to the surface of this tissue before ovule fertilization can occur. Pollen tube growth on the septum tracks the intercellular junctions of the septum epidermis where the secretion leaks out through a torn cuticle. Tubes must grow across the obturator before reaching the micropyle of an ovule. The temporal pattern with which tubes growing into the ovary exit the septum can contribute to the previously observed nonrandom patterns of fertilization (Hill and Lord, 1986).  相似文献   

12.
记述了在山东省五图盆地下始新统发现的一种“伪齿兽集目”化石 :千禧福兽 (Olbither iummillenariusumgen.etsp .nov.)。千禧福兽其颊齿形态基本上与原始奇蹄类相似 ,同时也具有伪齿兽类的一些特征 ,如m1~ 2下次尖没有与下内尖直接连接的下次脊。千禧福兽的M3次尖具前、后棱 ,这一点似与原始的蹄兔Seggeurius相似。因此 ,新种在目一级的归类有困难 ,暂置于McKenna ( 1 975 )创立的“伪齿兽集目”(“MirorderPhenacodonta”)。千禧福兽的发现进一步证明了奇蹄类可能起源于亚洲和北非类似伪齿兽类 (phenacodontids)的古有蹄类 ,福兽仅是类似伪齿兽类的古新世古有蹄类向奇蹄类进化过程中的一叉支的代表。  相似文献   

13.
Abstract:  Small reptiles from the Early Jurassic Pant 4 fissure fill in Glamorgan, South Wales (St. Bride's Island, Pant Quarry), were formerly provisionally attributed to three species of sphenodontian lepidosaurs. A re-analysis, aided by new material, has found this herpeto-fauna to consist almost exclusively of a single new species, Clevosaurus convallis sp. nov . , with only one specimen referable to Sphenodontia incertae sedis . Clevosaurus is known from the Upper Triassic and Lower Jurassic in various parts of the world, but C. convallis represents the first occurrence of the genus in the Jurassic of Britain. The material is fragmentary but includes numerous premaxillae, maxillae, dentaries and palatines, and the new species is distinguished by the unique combination of six large additional dentary teeth and a very short nasal process of the premaxilla, along with the diagnostic Clevosaurus features.  相似文献   

14.
Abstract:  The largest known flying organisms are the azhdarchid pterosaurs, a pterodactyloid clade previously diagnosed by the characters of their extremely elongate middle-series cervical vertebrae. The named species of the Azhdarchidae are from the Late Cretaceous. However, isolated mid-cervical vertebrae with similar dimensions and characters have been referred to this group that date back to the Late Jurassic, implying an almost 60 million year gap in the fossil record of this group and an unrecorded radiation in the Jurassic of all the major clades of the Pterodactyloidea. A new pterosaur from the Early Cretaceous of Liaoning Province of China, Elanodactylus prolatus gen. et sp. nov., is described with mid-cervical vertebrae that bear these azhdarchid characters but has other postcranial material that are distinct from the members of this group. Phylogenetic analysis of the new species and the Pterodactyloidea places it with the Late Jurassic vertebrae in the Late Jurassic–Early Cretaceous Ctenochasmatidae and reveals that the characters of the elongate azhdarchid vertebrae appeared independently in both groups. These results are realized though the large taxon sampling in the analysis demonstrating that the homoplastic character states present in these two taxa were acquired in a different order in their respective lineages. Some of these homoplastic characters were previously thought to appear once in the history of pterosaurs and may be correlated to the extension of the neck regions in both groups. Because the homoplastic character states in the Azhdarchidae and Ctenochasmatidae are limited to the mid-cervical vertebrae, these states are termed convergent based on a definition of the term in a phylogenetic context. A number of novel results from the analysis presented produce a reorganization in the different species and taxa of the Pterodactyloidea.  相似文献   

15.
《Journal of morphology》2017,278(11):1586-1597
In a study aiming to improve knowledge on the mineralization of the axial skeleton in reared Siberian sturgeon (Acipenser baerii Brandt, 1869), we discovered a new mineralized tissue within the notochord. To our knowledge, such a structure has never been reported in any vertebrate species with the exception of the pathological mineralization of the notochord remains in degenerative intervertebral disks of mammals. Here, we describe this enigmatic tissue using X‐ray microtomography, histological analyses and solid state NMR‐spectroscopy. We also performed a 1‐year monitoring of the mineral content (MC) of the notochord in relation with seasonal variations of temperature. In all specimens studied from 2‐year‐old juveniles onwards, this mineralized structure was found within a particular region of the notochord called funiculus . This feature first appears in the abdominal region then extends posteriorly with ageing, while the notochord MC also increases. The mineral phase is mainly composed of amorphous calcium phosphate, a small amount of which changes into hydroxyapatite with ageing. The putative role of this structure is discussed as either a store of minerals available for the phosphocalcic metabolism, or a mechanical support in a species with a poorly mineralized axial skeleton. A pathological feature putatively related to rearing conditions is also discussed.  相似文献   

16.
黄庆昌  黄桂玲  杨曼玲   《广西植物》1993,(1):70-73+100
对11科13属种半红树植物的营养器官进行了生态解剖的研究,主要特征是:通气组织和贮水组织不很发达,具有散孔材及旱年结构。地上根系、异常次生结构、木栓瘤和下皮只见于少数植物。结果表明:半红树植物不只有或少许具有真红树植物独特的结构。没有趋同适应。显示了结构与环境的密切关系。  相似文献   

17.
本文系统研究了广西南垌早石炭世巴平组下段丰富的牙形刺,识别出Siphonodella duplicata,S.cooperi,S.obosoleta,S.quadruplicata,S.lobata,S.crenulata,S.sandbergi,S.eurylobata,S.isosticha,Gnathodus delicatus等重要的带化石。首次报道和描述了产自Siphonodella crenulata带下部牙形刺新材料,其中确立一新种:Siphonodella nandongensis sp.nov.Li;一新未定种:Siphonodellasp.nov.A;且修订了Siphonodella trirostrata Druce(1969)的含义。依据上述牙形刺:Siphonodella nandongensis sp.nov.Li;Siphonodellasp.nov.A和Siphonodella trirostrata Druce(1969)发育特征,认为Siphonodella nandongensis sp.nov.Li与Siphonodella sexplicata;Siphonodella sp.nov.A与Siphonodella quadruplicata(Branson et Mehl);Siphonodella trirostrata Druce(1969)与Siphonodella sandbergi Klapper演化关系密切,并确定所描述的化石新材料的层位是Siphonodella crenulata带下部,地质时代为早石炭世早期,为进一步精细地层划分提供了翔实资料。  相似文献   

18.
Abstract:  The modern study of fossil crinoids began with J. S. Miller who, in 1821, described specimens from southern England, nearby Wales and other regions, and named several common Early Carboniferous genera. Later, in 1950–60, James Wright monographed all known Early Carboniferous crinoids from the British Isles. In spite of such previous scrutiny, we recognize here two new genera among species already described: Glamorganocrinus gen. nov. (type species: Ophiurocrinus gowerensis Wright, 1960) from South Wales and Mendipocrinus gen. nov. (type species: Poteriocrinus latifrons Austin and Austin, 1847) from southern England. These new genera increase the number of advanced cladid genera in the Ivorian Substage of the Tournaisian in western Europe to 18, and the total number of crinoid genera to 36. A review of species assigned to Mespilocrinus has led to the recognition of M. granulifer De Koninck and LeHon, 1854 as a nomen dubium. A new species of Mespilocrinus , M. wrighti sp. nov., is described from the Ivorian of South Wales; this is the most highly derived species of the genus, as based on a phylogenetic analysis including ten species and 13 characters, with Pycnosaccus as the outgroup. A single, well-ordered tree resulted from this analysis. Interpretation of this tree suggests that the centre of evolution for Mespilocrinus was North America, where three species appeared during the Kinderhookian (early Tournaisian), rapidly achieving morphological disparity within the genus. This radiation event was part of the overall explosive radiation of crinoids following the Late Devonian mass extinction event when crinoid diversity was at a global minimum during the Frasnian. Recovery began during the Famennian, followed by an explosive radiation in the Tournaisian.  相似文献   

19.
Picea eichhornii n. sp. is described from anatomically preserved seed cones. The fossils are from the Early Oligocene Jansen Creek Member of the Makah Fm. which is exposed along the northern shore of the Olympic Peninsula, Washington. The cones are at least 5.5 cm long and up to 3.5 cm in diameter. The cone axis is 4–6 mm in diameter and contains a pith made up of thick-walled parenchyma cells. Resin canals occur in a single ring in the secondary xylem in some specimens but are absent in others. The cortex is mostly parenchymatous and contains numerous large axial resin canals that branch to supply the bract and scale. Vascular traces to each scale and its subtending bract diverge separately from the vascular cylinder of the cone axis. The bract is tongue-shaped and keeled at its base. It is 5 mm wide and up to 9 mm long. The bract trace fades out before entering the bract base while two resin canals extend into the bract base. The ovuliferous scale is about 2.3 cm long and has a thin, probably papery, apex. Resin canals of the scale occur abaxial to the vascular tissue in the scale base, but some bend around the margins of the vascular strand to become adaxial outward. About 20 resin canals occur in the abaxial scale sclerenchyma, and this is the main anatomical feature that distinguishes these cones as a new species. There are less than 14 such canals in cones in a reference collection of 15 modern species and in the two fossil species known from anatomically preserved material. While the new species adds to our knowledge of the diversity of Cenozoic Picea, its affinities within the genus remain undetermined.  相似文献   

20.
A proper knowledge of the vertical organization of the phytoplankton is of fundamental importance for our understanding of the functions of pelagic ecosystems. Essential in this context is the existence of vertical gradients in environmental parameters. However, little is known about how the fine vertical structures of phytoplankton species are formed and maintained. In situ study of phytoplankton is biased by the fact that submersing instruments can disturb or even destroy the fine vertical gradients in species composition and/or cell numbers. We have designed and constructed an optical instrumentation system by which fine-scale vertical displacements of microalgae can be studied in an artificial water column without influencing fine physical, chemical, and biological structures of the water column. This enables us to find out more about the fine-scale behavioral responses of microalgae to vertical gradients in environmental parameters. We describe the main system, present some test results, and conclude that our optical system is able to reveal fine-scale vertical displacements of microalgae in an artificial water column and that the system can detect differences in cell densities down to 100 cells·mL−1.  相似文献   

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