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1.
A new baby pterodactyloid pterosaur with soft tissue preserved.Ningchengop terus liuae gen. et sp.nov.,is erected based on a nearly complete skeleton with a skull.It was characterized by the skull, slightly longer than the combined length of the dorsal and sacral vertebrae;50 teeth(including upper and lower jaws);short mid-cervical vertebrae;the humerus and the scapula, equal to that of the wing metacarpal in length;the ulna and the femur, equal to that of the first and third wing phalanx in length, respectively.The similar ratio of the wing phalanx 2 to wing phalanx 1 of Ningchengopterus and Eosipterus implies that Ningchengopterus may be close to the ctenochasmatid pterosaur.However, it may also imply that the isometrically growing of the first two wing phalanges exists among some pterosaurs.  相似文献   

2.
1 Introduction The Jiufotang Formation is one of the most fossil- productive Early Cretaceous deposits of China. It overlies the famous Yixian Formation from which many important taxa were found (Ji et al., 2004; Chang et al., 2003; Zhou et al., 2003). In addition to other vertebrates, pterosaurs, the first flying reptiles in Earth history, are also abundant in the Jiufotang Formation. At present, nine species belonging to five genera have been reported from the Jiufotang Formation. The…  相似文献   

3.
Discovery of a New Pterosaur in Western Liaoning,China   总被引:2,自引:0,他引:2  
The pterosaur from the Yixian Formation in Beipiao, Liaoning Province, ischaracterized by the medium-sized individual, short tail, presence of the gastralia, strongforelimbs, radius and ulna longer than wing-metacarpal, extremely narrow and elongatemetatarsals, degenerated and small phalanx V of hindlimb and so on. It must be a new genusand species, Eosipterus yangi gen. et sp. nov., in the early groups of the SuborderPterodactyloidea. This is the first record of pterosaurs found in Liaoning Province. The fossilprovides new evidence for further determining the nature and geological time of the JeholFauna and for studying the palaeogeography and palaeoenvironment.  相似文献   

4.
记辽宁一新翼龙化石(喙嘴龙亚目)   总被引:21,自引:0,他引:21  
姬书安  季强 《江苏地质》1998,22(4):199-206
记述了辽宁北票四合屯炒米甸子组中一新翼龙化石,该翼龙个体极小,两翼展开仅约40cm。化石具有同形齿、长尾、极短的翼掌骨和非常发育的后肢第Ⅴ趾等特征,因而无疑可归入喙嘴龙亚目喙嘴龙科(Rhamphorhynchidae),并代表一新属种弯齿树翼龙(Dendrorhynchuscurviden-tatusgen.etsp.nov.)。该化石是我国及东亚晚侏罗世喙嘴龙类翼龙的首次记录,它的发现有力地表明包括中华龙鸟和孔子鸟在内的辽西四合屯化石层的地质时代应为晚侏罗世。  相似文献   

5.
A new basal non-pterodactyloid pterosaur, Changchengopterus pani gen. et sp. nov., is erected, on the basis of a nearly complete postcranial skeleton. The new taxon is distinguished by relatively short extensions of the prezygapophyses, postzygapophyses and haemal arches of the caudal vertebrae; a humerus that has a subtriangular deltopectoral crest; limb elements that decrease in length in the following order: ulna> wing-phalange 2 > wing-phalange 3 = wing-phalange 1>humerus >tibia>femur>wing-metacarpal. Phylogenetic analysis suggests that Changchengopterus is a basal member of rhamphorhynchoids, and more closely related to Dorygnathus than to other rhamphorhychoids. The geological age of the Changchengopterus -bearing sediments is no latter than the end of the Late Jurassic and it is possible Middle Jurassic.  相似文献   

6.
A new baby pterodactyloid pterosaur with soft tissue preserved, Ningchengopterus liuae gen. et sp. nov., is erected based on a nearly complete skeleton with a skull. It was characterized by the skull, slightly longer than the combined length of the dorsal and sacral vertebrae; 50 teeth (including upper and lower jaws); short mid-cervical vertebrae; the humerus and the scapula, equal to that of the wing metacarpal in length; the ulna and the femur, equal to that of the first and third wing phalanx in length, respectively. The similar ratio of the wing phalanx 2 to wing phalanx 1 of Ningchengopterus and Eosipterus implies that Ningchengopterus may be close to the ctenochasmatid pterosaur. However, it may also imply that the isometrically growing of the first two wing phalanges exists among some pterosaurs.  相似文献   

7.
郭洋  李清  徐文龙  钱路  田策 《岩土力学》2018,39(10):3882-3890
采用动态焦散线试验和ABAQUS数值分析方法,对条形药包爆破载荷作用下不同角度预制贯通裂纹的扩展行为进行了研究。研究结果表明:在爆炸应力波的作用下,柱部区域和端部区域0°预制贯通裂纹远端翼裂纹背离炮孔方向扩展,而近端翼裂纹朝向炮孔扩展。预制贯通裂纹远端的应力集中程度较近端高,并且远端翼裂纹的止裂韧度更低,翼裂纹更易扩展。在爆炸应力波的作用下,柱部区域90°预制贯通裂纹由张开逐渐转为闭合,爆炸应力波在已闭合的预制贯通裂纹面发生透射,并在预制贯通裂纹尖端产生压剪应力集中,形成以II型断裂为主的I-II复合型裂纹,并近似垂直于预制贯通裂纹面扩展,随后,在自由面反射应力波的作用下,反翼裂纹沿预制贯通裂纹面起裂扩展;炮孔端部区域90°预制贯通裂纹处翼裂纹的起裂是由于爆炸应力波在预制贯通裂纹处产生反射拉伸波的结果,促使预制贯通裂纹端部产生拉应力集中,形成近似I型裂纹,随后,翼裂纹逐渐转向爆炸应力波传播方向扩展。  相似文献   

8.
爆炸应力波作用下缺陷介质裂纹扩展的动态分析   总被引:2,自引:0,他引:2  
采用透射式焦散线测试系统,进行爆炸应力波作用下缺陷介质裂纹扩展试验,研究了含与炮孔共线的预制裂隙介质裂纹扩展速度、加速度、裂纹尖端动态应力强度因子和动态能量释放率的变化规律以及它们之间的变化关系。试验结果表明,在爆炸应力波作用下裂隙两端产生了两条翼裂纹A、B,翼裂纹A的长度较翼裂纹B长,两条翼裂纹向相反的方向扩展;在翼裂纹扩展过程中,存在着加速与减速的过程,扩展速度瞬间达到峰值,其后逐渐振荡下降;动态应力强度因子也呈现瞬间达最大值到逐渐减小连续振荡变化的趋势,动态应力强度因子 > ;翼裂纹尖端的动态能量释放率对裂纹扩展具有驱动作用。  相似文献   

9.
Cretornis hlavaci Frič, 1881 from the Upper Cretaceous (Turonian) of Czech Republic is a valid taxon referred to Azhdarchoidea based on having a saddle-shaped humeral head, pneumatic foramen on proximal humerus present on anterior side and absent on posterior side, elongate deltopectoral crest with subparallel proximal and distal margins, pneumatic foramen absent on distal side of humerus, metacarpals I–III not articulated with carpus and displaced on anterodorsal side of wing metacarpal, and wing metacarpal much longer than humerus. Absence of a pneumatic foramen on posterior side of proximal humerus suggests attribution of Cretornis hlavaci to Neoazhdarchia. It has a unique construction of the distal ulna with a dorsal articulation surface placed distinctly proximal to the tuberculum shared only with the non-azhdarchid azhdarchoid Montanazhdarcho minor from the Campanian of North America. Cretornis hlavaci differs from the latter taxon by the structure of its humerus and distinctly longer wing metacarpal. It is more derived than “Tapejaridae” but shares with Azhdarchidae the deltopectoral crest of the humerus displaced distally from humeral head. Cretornis cannot be assigned to Azhdarchidae because of the oval cross section of the second wing phalanx. A unique rhombic outline of the distal humerus of Cretornis hlavaci is a possible autapomorphy for this taxon. Its wing span estimated as 1.5–1.6 m. This is the first taxon of non-azhdarchid pterosaurs known from the Upper Cretaceous of the Eastern Hemisphere.  相似文献   

10.
曲线翼型裂纹扩展路径理论分析及试验验证   总被引:1,自引:0,他引:1  
李强  杨庆  栾茂田  贾景超 《岩土力学》2010,31(2):345-349
采用数值和试验的方法对翼型裂纹的扩展路径进行分析,发现单轴下张开型裂纹的翼型裂纹的扩展路径逼近于过原主裂纹中心点、平行于最大主应力的一条直线。基于翼型裂纹路径这个特点,采用了双曲线参数方程近似表达真实翼型裂纹的扩展路径,通过翼型裂纹的起裂角、起裂点及翼型裂纹的渐近线方程求解了双曲线方程中的未知参数。采用双曲线翼型裂纹路径和试验中所得翼型裂纹路径进行了对比分析,二者吻合得很好,验证了采用双曲线近似表示真实存在的翼型裂纹模型的正确性。应用双曲线翼型裂纹模型对翼型裂纹的扩展和失稳进行分析,采用ABAQUS求解了双曲线翼型裂纹模型的应力强度因子,并与试验进行对比,发现双曲线翼型裂纹模型能很好地解释翼型裂纹的实际扩展规律,这表明了采用双曲线近似表示真实翼型裂纹路径的有效性。  相似文献   

11.
The cross-section and surface structures of wing membranes from the ctenochasmatid pterosaur Beipiaopterus chenianus were observed through a scanning electron microscope (SEM). The results show that the wing membrane contains a high density of blood vessels, implying strong thermoregulatory function, similar to that of a bat wing membrane. This is the first comparison of the microstmctures of pterosaur wing membranes with those of the modem bat. It is inferred that a bat-like physiology exists, at least in relatively small pterosaurs suggesting that these pterosaurs were warm-blooded, active fliers.  相似文献   

12.
根据新材料,对始无齿翼龙的特征进行了修订:中部颈椎体没有神经棘;肱骨三角嵴的长度与肱骨长度之比率约为0.25;翼掌骨的长度与第二翼指骨的长度几乎相等;第二翼指骨与第一翼指骨的长度之比率约为0.76.始无齿翼龙的新标本与正型稍微不同,可能由个体发育所引起.  相似文献   

13.
More than 30 forewings of Mesoblattina vitimica n. sp. were examined for variation in number and distribution of veins. Considerable variation in the R system between the number of simple branches running towards the anterior margin of the wing, and the number of apical branches is present, but the total number of branches in the system is relatively constant. The number of stems into which the principal vein of the M 'system divides is more constant than the number of branches of this system emerging at the wing margin. The least variable characters are therefore the most reliable for systematics. Comparisons are made with other Jurassic and Cretaceous species of Mesoblattina. — C. R. Palmer.  相似文献   

14.
Makarkinia kerneri sp. nov. is described from the Lower Cretaceous Crato Formation of Brazil, based on an incomplete but very well-preserved hind wing (Neuroptera: Kalligrammatidae). The previously presumed attribution of the genus is confirmed, based on the diagnostic characters of its wing venation (e.g., dense crossvenation; the anteriorly directed branches of MP) and the presence of a distinct eye-spot on the wing. Makarkinia is the only American representative and youngest known genus of Kalligrammatidae. With an estimated wing length of 100–160 mm, it has the largest wings amongst all fossil and extant Neuroptera.  相似文献   

15.
高水压下岩体裂纹扩展的渗流-断裂耦合机制与数值实现   总被引:1,自引:0,他引:1  
赵延林  彭青阳  万文 《岩土力学》2014,299(2):556-564
采用渗流力学、断裂力学理论结合Monte Carlo方法描述岩体裂纹的随机分布,研究高水压作用下岩体原生裂纹的变形和翼形裂纹的萌生、扩展、贯通的渗流-断裂耦合作用机制,建立高水压作用下岩体裂纹的渗流-断裂耦合数学模型,给出该数学模型的求解策略与方法,在Fortran95平台下开发高水压下岩体裂纹扩展的渗流-断裂耦合分析程序HWFSC.for。高水压下岩体裂纹扩展的渗流-断裂耦合体现在岩体裂纹网络和渗流初始条件都随渗流时步变化。对高压注水岩体裂纹扩展过程进行渗流-断裂耦合分析。结果表明,高压注水条件下,岩体裂纹扩展存在起动水压力,当水压力大于起动水压力时,裂纹尖端开始萌生翼形裂纹,随着裂纹水压力的增加,翼形裂纹扩展,进而与其他裂纹搭接贯通,停止扩展。渗流-断裂耦合分析考虑了裂纹动、静水压力对裂纹产生的法向扩张效应及翼形裂纹的扩展而形成新的渗流通道两方面的影响,连通裂纹数随渗流的发展而增加。岩体裂纹的渗流-断裂耦合分析,能较真实地再现岩体裂纹的水力劈裂现象,描述岩体裂纹的扩展、贯通过程及与之相耦合的渗流响应。  相似文献   

16.
本文记述山东莱阳盆地早白垩世莱阳组(K1l3)的扁足蝇科的1个新亚科—中国盗蝇亚科(Sinotestinae subfam.nov.).新亚科以其Sc很长,D很小,短于b1,M1与M2呈叉形等等特征区别于其它两个亚科—扁足蝇亚科(Platypezinae)和小神蝇亚科(Microsaniinae);与此同时,它又兼有上述两个亚科的某些特征;在地史分布上又是早期出现的独特新类群,在分类上应有它本身的位置.文中并将含昆虫化石的地层剖面作了简要的描述.  相似文献   

17.
袁小平  刘红岩  王志乔 《岩土力学》2012,33(6):1679-1688
基于Drucker-Prager(下简称D-P)准则,建立压缩载荷作用下的非贯通节理岩石的弹塑性断裂模型。针对节理岩石小范围屈服翼裂纹尖端塑性区,推导了D-P屈服准则的纯I、纯II及I、II复合型3种翼裂纹无量纲塑性区径长函数,并与Mises准则的塑性区进行对比;结果表明,D-P准则的I型和复合型塑性区较Mises屈服准则的塑性区大,且其II型及I、II复合型塑性区在翼裂纹上下表面不连续。进一步,引入断裂软化因子以表征节理岩石裂隙断裂扩展后的断裂软化规律,考虑非贯通节理岩石复合型断裂软化,是由于节理尖端翼裂纹应变能密度超过最小应变能密度导致其成核扩展引起的,提出用应变能密度的指数函数形式表征断裂软化变量的演化;塑性屈服函数采用Borja等的应力张量3个不变量的硬化/软化函数,反映塑性内变量及应力状态对硬化函数的影响;建立节理岩石的弹塑性断裂本构关系及其数值算法,并用回映隐式积分算法编制了弹塑性断裂模型的程序。以单轴压缩下非贯通节理岩石为例,分析岩石断裂韧度、节理摩擦系数和节理倾角等参数的影响,结果表明,所提出的弹塑性断裂模型与数值和试验结果比较吻合。  相似文献   

18.
通过对动力三角翼低空磁测数据在多宝山地区的质量评价,证明动力三角翼低空磁测方法采集的数据真实可靠。在取得质量较好的数据前提下,将多宝山地区其他实测结果与动力三角翼测量结果进行对比分析,证明动力三角翼低空磁测方法具有高效、工作控制范围大、一定程度上能削弱地表人工磁性体的干扰等优势,从而能成为一种快速而有效的磁法测量手段。  相似文献   

19.
刘刚  姜清辉  熊峰  张小波 《岩土力学》2016,37(Z1):151-158
为了研究不同倾角下多节理岩体力学行为,采用10 MN微机控制电液伺服大型多功能动静力三轴仪,开展包含较多预制非贯通节理类岩石试件的单轴压缩试验,研究了多节理岩体裂纹的特征、贯通模式、破坏模式、应力-应变特征等与节理倾角之间的关系。试验结果表明,(1)多节理岩体的裂纹类型主要有翼裂纹和次生共面裂纹,翼裂纹的扩展路径与单个节理情况下的扩展路径差异较大,翼裂纹起裂后沿起裂方向存在较长的扩展长度,直接与相邻节理或翼裂纹形成贯通,并且裂纹的贯通表现出四种不同的模式;(2)多节理岩体的破坏模式归纳为3种类型:平面破坏、块体转动式破坏和台阶式破坏;(3)根据多节理岩体的应力-应变曲线在应变软化阶段所表现出的不同非线性变形行为特征,可以将曲线归纳为4种类型;(4)多节理岩体的强度和变形各向异性特征非常显著,强度和弹性模量均在节理倾角30°时最小,90°时最大。  相似文献   

20.
One new osmylid genus and species, Burmaleon magnificus, and one new nymphid genus and species Rafaelnymphes cratoensis are described, respectively based on inclusions in the Cretaceous Burmese amber and on a compression fossil from the Crato Formation in Brazil. The nymphid Araripenymphes seldeni, from the Crato Formation, is redescribed on the basis of a new specimen, showing possible sexual dimorphism in wing coloration, a feature extremely rare among the Neuroptera. In a recently published phylogenetic analysis of the family, the attribution to the fossil taxa (versus rejection) of the larval characters proper to the modern nymphids, has a crucial impact on the resolution of the phylogeny. The compression fossils currently attributed to the Nymphidae should be revised because their wing venation alone is not really sufficient for an accurate family attribution to Nymphidae rather than to another family of Neuroptera (viz. Osmylidae).  相似文献   

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