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1.
中国鲨类脑颅的研究   总被引:2,自引:0,他引:2  
本文解剖观察了我国有代表性的鲨类脑颅共32种,分隶于8目14科24属。研究结果认为鲨类的脑颅共可分为9个式型和12个亚型。现存虎鲨目、须鲨目的鲸鲨科和扁鲨目吻软骨缺如,六鳃鲨目、须鲨目、角鲨目和锯鲨目均具一吻软骨,它们是一些古老和一些特化的类群。现存大多数种类均具3根吻软骨。在各不同分类阶元常有其不同的形态特征,可作为分类依据之一,亦可显示其亲缘关系。  相似文献   

2.
李思忠  王惠民 《动物学报》1989,35(2):213-221
本文研究了中国鲽形目8科、27属和约40种的脑颅骨;指出其脑颅骨的最显著特征是前部左右不对称,并首次发现鳒科无基蝶骨(与Berg,1940,1955及Nelson,1984的记载不同),副蝶骨延及基枕骨腹侧后端或附近(与Amaoka,1969及Ochiai,1963的记载也不同)和冠鲽科无眶间突且左右前额骨互连。还依它们脑颅骨的异同,探讨了其演化程度,并拟有中国鲽形目各亚目及科的检索表。  相似文献   

3.
钝头蛇亚科Pareinae隶属游蛇科Colubridae分布于10°S—35°N,80°—125°E的东南亚及其邻近岛屿,是具有吻钝,无颏沟和上颌骨前端无齿等特殊性状的唯一类群,原记载共2属16种。经全面分类清理后,该类群共有18种,分别隶属Pareas Wagler,Aplopeltura Dumeril et Bibron和Internatus gen.nov.三属,其中Pareas具派生性状最少为最原始,Aplopeltura具派生性状最多为最特化。Aplopeltura和Internatus可能分别源自Pareas的某一级或不同级的祖先,可能是第四纪大冰期时先后从大陆迁入马来半岛、苏门答腊、婆罗洲、爪哇和菲律宾南部,然后在间冰期和冰后期因适应岛屿环境而特化成的新类群。  相似文献   

4.
大口黑鲈和尖吻鲈骨骼系统的比较研究   总被引:6,自引:0,他引:6  
对大口黑鲈和尖吻鲈的骨骼系统进行了比较研究。结果表明 :从整体看 ,大口黑鲈的脑颅较宽 ,吻短钝 ,眼后头部短 ;尖吻鲈的脑颅狭窄 ,吻部尖长而突出 ,眼后头部较长。各部分的骨骼特征 :大口黑鲈脑颅的中筛骨、侧筛骨、额骨、上枕骨、上耳骨、翼耳骨和围眶骨等与尖吻鲈有明显的区别 ;大口黑鲈咽颅中的前颌骨、齿骨、中翼骨、鳃盖骨骼、角舌骨、尾舌骨、下咽骨等与尖吻鲈又有显著的差异 ;大口黑鲈附属骨骼中的肩带骨、腰带骨、脊椎骨等有很大的不同。这些差异和不同可作为科间或属间分类依据。  相似文献   

5.
本文解剖观察了鳐类尾部肌肉横切面,计36种50余尾,分隶于19属、15科、4目。对同种不同大小个体亦作了比较分析,其性状稳定;肌肉的形态特征与不同生态类型有密切的关系,可依此分为4种式型6亚型。在不同分类阶元,各有独特的特征,借此可作为鉴别分类依据之一。  相似文献   

6.
论中国软骨鱼类的地理分布和区系特征   总被引:2,自引:0,他引:2  
中国的软骨鱼类,就现时所知,共有127种、60属、28科,可归纳为如下14大类:(1)六鳃鲨类,有六鳃鲨1科3属3种;(2)虎鲨类,有虎鲨1科1属2种;(3)鼠鲨类,有锥齿鲨、鼠鲨、姥鲨、长尾鲨、须鲨和鲸鲨6科11属18种;(4)猫鲨类,有猫鲨、皱唇鲨、真鲨和双髻鲨4科19属43种;(5)角鲨类,只有角鲨1科2属4种;(6)锯鲨类,有锯鲨1科1属1种;(7)扁鲨类,有扁鲨1科1属2种;(8)锯鳐类,有锯鳐1科1属2种;(9)犁头鳐类,有犁头鳐和团扇鳐2科4属9种;(10)电鳐类,有电鳐和单鳍电鳐2科3属5种;(11)真鳐类,只真鳐1科1属7种;(12)魟类,有魟和燕魟2科5属17种;(13)鲼类,有鲼、鹞鲼、牛鼻鲼和蝠鲼4科6属12种;(14)银鲛类,只有银鲛1科2属2种。中国软骨鱼类的区系组成的特点以真鲨科、魟科和鲼科最为繁盛,其次是须鲨、猫鲨、长尾鲨和双髻鲨等科,但角鲨科、真鳐科和银鲛科的代表性则均较弱。中国软骨鱼类可分为暖水性种、暖温性种和冷温性种三种类型。暖水性种有74种,占中国软骨鱼类总数的59%;暖温性种有39种,占30%;冷温性种有14种,占11%。  相似文献   

7.
蚤类背腹位标本的研究   总被引:2,自引:0,他引:2  
叶瑞玉  于心 《昆虫学报》1986,(4):436-445
蚤类是医学昆虫中的一个重要类群,因其体形高度特化而呈侧扁,故在形态描述及分类鉴定时多将其制成左右扁平的侧位标本进行观察。这种方法已为蚤类学工作者长期沿用,在分类工作中起了重要的和主导的作用。但亦不可否认该法存在一定的缺点和局限性。因蚤体虽多侧扁,但背腹仍具一定厚度,制片中人为地左右压缩,将立体制成近乎平  相似文献   

8.
关于扁吻鱼属(Psilorhynchus)分类位置的探讨   总被引:1,自引:0,他引:1  
最近几年,许多学者都同意Hora(1925)和Ramaswami(1952)的观点,将扁吻鱼属提升到一个科的等级。作者对采自我国西藏墨脱(雅鲁藏布江)的平鳍扁吻鱼Psilorhynchus homaloptera Hora et Mukerji的外形和主要骨骼结构进行了观察,并采用分支分类学的方法对其特征进行了分析,得出了与上不同的结论。扁吻鱼属具有大量一般鲤科鱼类的共同特征(包括离征和祖征),表示它是与所有的鲤科鱼类起源于一个共同的祖先。它们又与鲤科的墨头鱼类群(Garrini group)具有许多共同离征,证明它们是从一个共同的原始鲤科鱼类祖先派生出来的单源群。而与墨头鱼类比较,扁吻鱼属具有许多更特化的离征和个别较原始的祖征,这种相对原始和相对特化的特征的镶嵌分布,证实它们是一对姐妹群。因此,作者认为扁吻鱼属在系统发育中仅具有与墨头鱼类群相同的等级,如果将墨头鱼类作为鲤科中的一个亚科,也应将扁吻鱼属隶属于鲤科的一个相应的亚科——扁吻鱼亚科Psilorhynchinae。  相似文献   

9.
在光学显微镜和扫描电镜下观察了南五味子属Kadsura 7种21个样品和五昧子属Schisandra 8种14个样品的木材解剖特征,结果表明次生木质部的导管分子类型、导管一射线间纹孔的排列方式、射线类型、射线细胞形状等性状在科的水平上很稳定,这些共同特征都支持五味子科Schisandraceae是比较自然的类群。在五昧子科中发现木材导管单生、具梯状穿孔板、导管壁具梯形排列的纹孔以及木射线异型等原始性状,支持五味子科在被子植物中的原始地位。此外,该科木材还具有单穿孔板导管、导管次生壁具螺纹加厚、具分隔纤维等较为特化的性状状态,这种性状进化水平的异等级现象,使五味子科表现出不同进化水平性状的镶嵌组合。根据木材解剖性状对五味子科进行UPGMA聚类分析,所得结果显示南五昧子属和五味子属在木材解剖特征方面有一定的交叉和重叠,这与分子系统学的结论一致,表明这两个属关系密切,可能起源于共同的祖先。通过比较五昧子科与八角科Illiciaceae的木材解剖特征,进一步证明两个科的亲缘关系很近,不支持将五味子科从八角目Illiciales中独立出来成立五味子目Schisandrales的观点。  相似文献   

10.
应用叶绿体DNAtrnL内含子序列分析檀香目科间的系统发育关系。取样研究的檀香目个体的trnL内含子序列长度在科间呈现较大差异(从291bp到587bp)。最大简约性分析产生的严格一致树与以前已发表的基于其它基因的檀香目的分子系统学研究结果大体一致。香芙木属(铁青树科)是最早分支出的类群:桑寄生科、槲寄生科分别表现为单系类群,檀香科为并系;桑寄生科和槲寄生科并不具密切亲缘关系,槲寄生科从檀香科内衍生出来。本研究表明,具相对高的核苷酸替换率的叶绿体DNAtrnL内含子序列可为高等级类群系统发育关系的研究提供更多的信息位点。  相似文献   

11.
鲂鱼的头骨发育及其适应意义   总被引:1,自引:0,他引:1  
赵俊  陈湘Lin 《动物学研究》1995,16(4):307-314
本文对鲂鱼(Megalobramaskolkovii)头骨的早期发育过程及其与鱼苗的存活功能需要之间的关系进行了研究。头骨发育的全过程可划分为5个阶段,即软颅阶段、咽颅膜骨附加阶段、脑颅开始骨化阶段、脑颅快速骨化阶段和骨化完成阶段。刚出膜仔鱼头部即有软骨存在,最先出现的硬骨是膜质上颌骨和主鳃盖骨,脑颅最先开始骨化的是基枕骨和侧枕骨,随后才是副蝶骨。头骨发育过程与鱼苗早期存活的功能需要之间有着密切的关系。  相似文献   

12.
The rostral cartilages of batoid fishes were examined to elucidate their development, morphology and homology. Comparison of a variety of rostral cartilages among elasmobranchs with other groups of vertebrates shows that rostral cartilages originate embryologically from the trabecula and/or lamina orbitonasalis. Because different morphogenetic patterns of the derivatives of the two embryonic cartilages give rise to a wide variety of forms of rostral cartilages even within elasmobranchs, and because morphogenesis involves complex interactions among participating structures in the ethmo-orbital area, we put forward conceptual and empirical discussions to elucidate the homology of the rostral cartilages in batoid fishes. With six assumptions given in this study and based on recent discussions of biological and historical homology, our discussions centre on: (1) recognition of complex interactions of participating biological entities in development and evolution; (2) elucidation of a set of interacting biological and evolutionary factors to define a given morphological structure; (3) assessment of causal explanations for similarities or differences between homologous structures by determining genetic, epigenetic and evolutionary factors. Examples of conceptual approaches are given to make the approaches testable. Although a paucity of knowledge of rostral cartilage formation is the major obstacle to thorough analysis of the conceptual framework, several tentative conclusions are made on the homology of rostral cartilages that will hopefully attract more research on development and evolution in vertebrate morphology. These are: (1) the rostral cartilage in each group of vertebrates examined can be defined by both developmentally associated and adult structural attributes, yet such data do not allow us to assess homology of a variety of forms of rostral cartilages at higher taxonomic categories; (2) the entire rostral cartilage in elasmobranchs is formed by the contribution of the embryonic trabecula and lamina orbitonasalis. The status of the development and homology of the rostral cartilage in holocephalans remains uncertain; (3) there is no simple picture of evolution of rostral cartilages among three putative monophyletic assemblages of elasmobranchs, galeomorphs, squaloids (possibly plus Squatina, Chlamydoselachus and hexanchoids as the orbitostylic group) and batoid fishes. It is highly likely that rostral cartilages in each subgroup or subgroups of these assemblages may be of phylogenetic significance but that it may not serve as a basis to unite these assemblages into much higher assemblages; (4) the tripodal rostral cartilage is unique in form in the group including some carcharhinoid and lamnoid sharks. The status of the analogous tripodal cartilage in some squaloids remains uncertain. The unfused tripodal cartilage of the electric ray Narke is interpreted as developmentally equivalent to, but not homologous with, the unfused or fused ones in the sharks; (5) the rostral cartilage in the electric ray Torpedo is uniquely formed because of its embryonic origin solely from the ventro-medial part of the lamina orbitonasalis, but it is regarded as homologous with the rostral cartilages which are formed by the trabecula and other components of the lamina orbitonasalis in other batoid fishes; (6) the cornu trabecula contributes to the formation of the ventral stem of the rostral cartilage at least in elasmobranchs, especially to a particular set of rostral cartilages, i.e. the tripodal rostral cartilage in the shark Scyliorhinus and dorso-ventrally flattened rostral shaft in the narcinidid electric rays; (7) there is a unique form of a rostral shaft with rostral appendix in skates and probably guitarfishes; (8) there is no rostral cartilage in adult benthic stingrays, pelagic stingrays Dasyatis violacea and Myliobatidae, although it is present in embryonic stages; (9) there is a unique form of the rostral cartilage as a rostral projection from the dorso-lateral part of the lamina orbitonasalis in pelagic stingrays Rhinopteridae and Mobulidae, which together with part of the pectoral fins, forms a pair of cephalic fins; (10) different developmental mechanisms may be responsible for the absence or loss of rostral cartilages in different groups, i.e. absence of the cartilage derived from the medial area of the trabecula in Torpedo vs absence of the rostral cartilage in benthic stingrays; (11) the rostral cartilages in some placental mammals (cetaceans and sirenians) arise only from the medial area of the trabecula because monotreme and placental mammals do not form the trabecula cranii; (12) some actinopterygians and sacropterygians possess a rostral cartilage which originates only from the medial area of the trabecula. One scombroid group, including Sardini and Thunnini, Scomberomorus, Acanthocybium, Istiophoridae and Xiphias, possesses a unique larval beak composed of the rostral cartilage, ethmoid cartilage and premaxillar bone. The development and homology of other rostral cartilages remain to be further elucidated; (13) urodeles possess a medial rostral process whose anlage is probably developmentally equivalent to that in batoid fishes but the occurrence in urodeles is either atavistic or unique (autapomorphic); (14) the upper jaw of tadpoles is unique in possessing the suprarostral cartilage; the anlage of the cartilage is probably developmentally equivalent to the outgrowth of the cornu trabecula in batoid fishes.  相似文献   

13.
The latest works on iniopterygians question their monophyly when considering only the neurocranium of the two families (Sibyrhynchidae and Iniopterygidae), which have different conditions of preservation. Some of the synapomorphies of the Iniopterygia concern the pectoral girdle and fins. However, the anatomy of these different elements is still poorly known in this taxon. Here we describe in details three dimensionally preserved cartilages of the pectoral girdle and fins of the sibyrhynchid Iniopera sp. These structures have been extracted virtually from phosphatised nodules thanks to conventional and synchrotron microtomography, using absorption and phase contrast based techniques in the later case. The pectoral girdle of Iniopera sp. consists of three elements, which are, from dorsal to ventral, a paired suprascapular cartilage, a pair of robust scapulocoracoids and an unpaired intercoracoid cartilage. The scapular part of the scapulocoracoids is extremely reduced and the suprascapular cartilages link the scapulcoracoids to the rear of the neurocranium. These characters may be iniopterygian synapomorphies. Iniopterygians, stem and crown-holocephalans share a basipterygium that articulates with the pectoral girdle and bears an enlarged first pectoral fin radial. Posteriorly, the basipterygium articulates with either a well-defined metapterygium (in crown-holocephalans) or a metapterygial axis (in stem-holocephalans).  相似文献   

14.
团头鲂骨骼系统的发育   总被引:3,自引:0,他引:3  
本文对团头鲂骨骼系统的发育进行了研究,观察了刚孵化的仔鱼到已具成鱼特征的幼鱼的骨骼发育过程,对脑颅、咽颅、韦伯氏器和脊椎骨、肩带和胸鳍支鳍骨、腰带和腹鳍支鳍骨以及奇鳍支鳍骨在不同生长阶段的形态特征进行了描述。讨论了韦伯氏器、复合神经骨及第二神经板等的发生过程;并根据团头鲂骨骼发育情况,讨论了头骨各骨片的性质。  相似文献   

15.
Fishes are often thought to have passed through mass extinctions, including the Cretaceous-Tertiary (KT) event, relatively unscathed. We show that neoselachian sharks suffered a major extinction at the K/T boundary. Out of 41 families, 7 became extinct (17±12%). The proportional measure increases at lower taxic levels: 56±10% loss of genera (loss of 60 out of 107) and 84±5% loss of species (loss of 182 out of 216). However, the Maastrichtian and Danian are characterized by a high number of singleton taxa. Excluding singletons we have calculated a 34±11% loss of genera and a 45±9% loss of species. The simple completeness metric (SCM) for genera displays a decrease from the Maastrichtian (94%) to the Danian (85%) indicating a rather complete fossil record of neoselachian genera. The extinctions were heavy among both sharks and batoids (skates and rays), but most severe among batoids, which lost almost all identifiable species. There were equal losses among open marine apex predators (loss of Anacoracidae, Cretoxyrhinidae, and Scapanorhynchidae) and durophagous demersal forms from the continental shelf and shallow seas (Hypsobatidae, Parapaleobatidae, Sclerorhynchidae, Rhombodontidae). Benthopelagic and deep-sea forms were apparently little affected. New families with similar ecological roles (Carcharhinidae, Isuridae, Torpedinidae) replaced these families in the Danian, and full diversity of the different shark and batoid groups had been recovered by the end of the Paleocene or early Eocene. Sharks and rays suffered levels of extinction entirely in line with other groups of organisms at the K/T extinction event.  相似文献   

16.
The ventral gill arch skeleton was examined in some representatives of batoid fishes. The homology of the components was elucidated by comparing similarities and differences among the components of the ventral gill arches in chondrichthyans, and attempts were made to justify the homology by giving causal mechanisms of chondrogenesis associated with the ventral gill arch skeleton. The ceratohyal is present in some batoid fishes, and its functional replacement, the pseudohyal, seems incomplete in most groups of batoid fishes, except in stingrays. The medial fusion of the pseudohyal with successive ceratobranchials occurs to varying degrees among stingray groups. The ankylosis between the last two ceratobranchials occurs uniquely in stingrays, and it serves as part of the insertion of the last pair of coracobranchialis muscles. The basihyal is possibly independently lost in electric rays, the stingray genus Urotrygon (except U. daviesi) and pelagic myiiobatoid stingrays. The first hypobranchial is oriented anteriorly or anteromedially, and it varies in shape and size among batoid fishes. It is represented by rami projecting posterolaterally from the basihyal in sawfishes, guitarfishes and skates. It consists of a small piece of cartilage which extends anteromedially from the medial end of the first ccratobranchial in electric rays. It is a large cartilaginous plate in most of stingrays. It is absent in pelagic myliobatoid stingrays. The remaining hypobranchial cartilages also vary in shape and size among batoid fishes. Torpedo and possibly the Jurassic Belemnobalis and Spathobatis possess the generalized or typical chondrichthyan ventral gill arch structure in which the hypobranchials form a Σ-shaped pattern. In the electric ray Hypnos and narkinidid and narcinidid electric rays, the hypobranchial components are oriented longitudinally along the mid-portion of the ventral gill arches. They form a single cartilaginous plate in the narkinidid electric rays, Narcine and Diplobatis. In guitarfishes and skates, the second hypobranchial is unspecialized, and in skates, it does not have a direct contact with the second ceratobranchial. In both groups, the third and fourth hypobranchials are composed of a small cartilage which forms a passage for the afferent branches of the ventral aorta and serve as part of the insertion of the coracobranchialis muscle. In sawfishes and stingrays, the hypobranchials appear to be included in the medial plate. In sawfishes, the second and third components separately chondrify in adults, but the fourth component appears to be fused with the middle medial plate. In stingrays, a large medial plate appears to include the second through to the last hypobranchial and most of the basibranchial copulae. The medial plate probably develops independently in sawfishes and stingrays. Because the last basibranchial copula appears to be a composite of one to two hypobranchials and at least two basibranchial copulae, the medial plate may be formed by several developmental processes of chondrogenesis. More detailed comparative anatomical and developmental studies are needed to unveil morphogenesis and patternings of the ventral gill arch skeleton in batoid fishes.  相似文献   

17.
Fluid flow generated by body movements is a foraging tactic that has been exploited by many benthic species. In this study, the kinematics and hydrodynamics of prey handling behavior in little skates, Leucoraja erinacea, and round stingrays, Urobatis halleri, are compared using kinematics and particle image velocimetry. Both species use the body to form a tent to constrain the prey with the pectoral fin edges pressed against the substrate. Stingrays then elevate the head, which increases the volume between the body and the substrate to generate suction, while maintaining pectoral fin contact with the substrate. Meanwhile, the tip of the rostrum is curled upwards to create an opening where fluid is drawn under the body, functionally analogous to suction-feeding fishes. Skates also rotate the rostrum upwards although with the open rostral sides and the smaller fin area weaker fluid flow is generated. However, skates also use a rostral strike behavior in which the rostrum is rapidly rotated downwards pushing fluid towards the substrate to potentially stun or uncover prey. Thus, both species use the anterior portion of the body to direct fluid flow to handle prey albeit in different ways, which may be explained by differences in morphology. Rostral stiffness and pectoral fin insertion onto the rostrum differ between skates and rays and this corresponds to behavioral differences in prey handling resulting in distinct fluid flow patterns. The flexible muscular rostrum and greater fin area of stingrays allow more extensive use of suction to handle prey while the stiff cartilaginous rostrum of skates lacking extensive fin insertion is used as a paddle to strike prey as well as to clear away sand cover.  相似文献   

18.
The dermal covering of most batoid fish is constituted by dermal denticles and by different series of tubercles or thorns. The repartition and the morphological variations of these structures can provide complementary information about the taxonomy of skates and rays. The variations in these dermal structures within Pristiforms, Rajiforms and Myliobatiforms have been studied, taking into consideration the number of tubercles, their location and their arrangement in different series. Following Hubbs and Ishiyama [30], two new terms and 15 new series are indicated. The characteristics of the arrangement and of the morphology of these structures can separate the Rajiforms, having spiny tubercles or thorns, from the Myliobatiformes, bearing lanceolate or heart-shaped tubercles. The main taxinomic characters found are: guitar fish characterized by two scapular series, one well-developed rostral series and tubercles with an anterolateral ornamentation (relief). Within this group, Rhinidae and Rhynchobatidae are set apart by the morphology of their tubercles (devoid of any anterolateral ornamentation), by the absence of a middorsal caudal series and by the presence of an outer supraspiracular series. Platyrhina and Platyrhinoidis are distinguishable by the absence of anterolateral relief and by the presence of anterolateral, lateral and parallel series. Rajoids are characterized by thorns, only one scapular series and sometimes a nucho-scapular triangle, malar and alar thorns in adults, and well-developed parallel and lateral series. Myliobatiforms are devoid of rostral, orbito-spiracular, malar, alar, anterolateral, parallel and lateral series but a caudal sting is present in most species. Sawfish are almost entirely devoid of tubercules, except for rostral ‘teeth’. The morphology and arrangement of the rostral teeth can differenciate the two genera within this family.  相似文献   

19.
中国软骨鱼类螺旋瓣的研究   总被引:2,自引:0,他引:2  
本文对隶于2亚纲13目31科(除姥鲨科外)45属的68种软骨鱼类瓣肠内螺旋瓣进行了比较观察,认为可分为3式型,绝大多数种类属螺旋型,并可再依瓣的数目分为4个亚型,少数种类为薄片型或画卷型。亲缘关系近的种类其式型和数目亦近似。螺旋瓣数目颇多的种类可分为凶猛性和食浮游生物温和性两类。有的种类瓣肠内壁及螺旋瓣上具褶襞,以增加吸收面积。  相似文献   

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