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1.
Shansisuchus shansisuchus Young,1964 was restudied on the basis of a new specimen.Some anatomical features that were either briefly or not described at all in the original study were detailed.The new specimen not only provides further information on the skull anatomy and the vertebral column but also expands the range of the geographical distribution of the taxon.With new information,the diagnosis of S.shansisuchus was emended and its phylogenetic relationships were further analyzed.S.shansisuchus differs from other archosauriforms primarily in the presence of a large subnarial fenestra anterior to the antorbital fenestra,tongue-in-groove articulations between the ascending process of the premaxilla and nasal and between the premaxilla and maxilla,a tall and posterodorsally directed ascending process of the maxilla,a knee-shaped process of the postorbital projecting into the orbit,a broad descending process of squamosal distally well forked and a large,deeply bow-shaped intercentrum tightly anchoring/capping the sharp ventral edges of two neighboring centra together in cervical and at least first eight dorsal vertebrae.With additional information derived from the new specimen,the phylogenetic relationships of S.shansisuchus were reanalyzed;it is closely related to Erythrosuchus-Vjushkovia clade. 相似文献
2.
Rebbachisauridae is a poorly understood clade of diplodocoid sauropod dinosaurs, currently known only from the Cretaceous of Africa, Europe and South America. European representatives are particularly rare and fragmentary. Here, we report an anterior caudal vertebra from the Barremian (Early Cretaceous) Wessex Formation of the Isle of Wight, off the southern coast of England. This specimen possesses several features known only in rebbachisaurids and shares two synapomorphies with the Afro-European taxa Demandasaurus darwini and Nigersaurus taqueti, both pertaining to the morphology of the neural spine. These features are the development of triangular lateral processes and the presence of an elliptical fossa on the lateral surface, bounded by the lateral lamina and postspinal rugosity. The Isle of Wight specimen also shares several features solely with Demandasaurus, indicating a close relationship with the Spanish taxon. These include the presence of a hyposphenal ridge, as well as an anteriorly excavated caudal rib that is restricted almost entirely to the neural arch. However, it differs from Demandasaurus in a number of ways, including the lack of excavation on the posterior surface of the caudal rib, the orientation of the neural spine, and the composition and morphology of the lateral lamina. In addition, the Isle of Wight vertebra possesses one potential autapomorphy: bifurcation of the elliptical fossa on the neural spine. However, because of the fragmentary nature of the material, a new name is not erected. Along with Demandasaurus and Histriasaurus boscarollii, this caudal vertebra indicates the presence of at least three European rebbachisaurid taxa and provides new anatomical information on this enigmatic clade of sauropod dinosaurs. 相似文献
3.
<正>A new dinosaur Chuxiongosaurus lufengensis gen.et sp.nov.is erected based on a nearly complete skull.The taxon is characterized by the lacrimal perpendicular to the ventral margin of the upper jaw,which is similar to that of Thecodontosaurus;a depression present on the dorsal profile of the snout behind the naris;the rostral profile of the maxilla slopes continuously towards the rostral tip;and the presence of 25 dentary teeth.It also displays prosauropod characters such as a relatively long skull,the slope of the maxillary rostral profile,and teeth that do not have basically constricted crowns.The new specimen is more basal than Anchisaurus and represents the first basal sauropod dinosaur from the Early Jurassic of China. 相似文献
4.
A new crocodyliform specimen is presented here found in the Cerro Castaño Member of the Cerro Barcino Formation (Chubut Group). The material consists of cranial and postcranial remains that represent a new taxon that has strong affinities with Peirosauridae, but also shares derived features present in Araripesuchus. The phylogenetic relationships of this new taxon were tested through a cladistic analysis depicting it as a member of the Peirosauridae. The inclusion of Barcinosuchus within this clade of basal mesoeucrocodylians is supported by the presence of hypapophyses up to the third or fourth dorsal vertebrae, anterolateral facing edge on postorbital, quadrate dorsal surface divided in two planes by a ridge; mandibular symphysis tapering anterirorly in ventral view, lateral surface of dentary convex anterior to mandibular fenestra, distal body of quadrate well developed, anteroposteriorly thin and lateromedially broad. The new specimen broadens the temporal and geographical distribution of Peirosauridae during the Cretaceous of Gondwana, representing the southern-most and the most ancient record of the group in Patagonia. The new material also provides insights on the postcranial anatomy of peirosaurids, a group that has been so far studied almost exclusively from cranial material. 相似文献
5.
WANG Xuri Jingmai K. O’Connor ZHAO Bo Luis M. Chiappe Gao Chunling Cheng Xiaodong 《《地质学报》英文版》2010,84(2):247-256
<正>We report on a new species of enantiornithine bird from the Lower Cretaceous Qiaotou Formation of northern Hebei,China.The new taxon,Shenqiornis mengi gen.et sp.nov.,possesses several enantiornithine synapomorphies but is unique from other known species.The specimen has a well-preserved skull that reveals new information about enantiornithine cranial morphology.The new taxon possesses a large postorbital with a long tapering jugal process indicating that some enantiornithines may have had a fully diapsid skull,as in Confuciusornis.The tooth morphology of the specimen is unique and likely represents a previously unknown trophic specialization within Enantiornithes. 相似文献
6.
R.W. Marjoribanks 《Tectonophysics》1976,32(3-4)
In the Ormiston Nappe Complex, west of Alice Springs, central Australia, a deformed zone up to 0.7 km thick is developed in the sedimentary Heavitree Quartzite. The deformed zone is adjacent to a major thrust fault and is defined by mylonitic foliation, which is parallel to the thrust plane and by isoclinal folds. Recognition of original detrital quartz grains allows strain ellipsoids to be measured across the zone. The strain generally plots in the flattening field and many specimens show pure flattening strain. The mylonitic foliation is an axial-plane structure to the folds and is parallel to the XY-plane of the strain ellipsoid. A quartz elongation lineation may be present within the foliation and is parallel to the principal extension direction (the X-axis) of the strain ellipsoid.Strain is accommodated principally by intracrystalline plastic deformation of the quartz grains. In detail the strain is not homogeneous and may vary even between adjacent grains of the same specimen. Quartz optic axis fabrics reflect this strain inhomogeneity. If the strain ellipsoid is an oblate spheroid, c-axes lie in small-circle girdles about the principal shortening axis (the Z-axis). With general triaxial strain, the c-axes lie in a great-circle girdle or girdles which intersect the foliation parallel to the intermediate strain axis (the Y-axis) and lie symmetrically about the Z-axis. A random population of grains from a specimen often shows a composite c-axis pattern between these two types.With approach to the thrust there is an increase in the amount of strain within the specimens. The increasing strain correlates with an increase in the degree of c-axis preferred orientation of the deformed detrital grains and in the amount of new strain-free grains present in the deformed quartzite. Adjacent to the thrust the quartzite is completely composed of polygonal new grains. The new grains probably formed under syntectonic conditions caused by movement along the thrust. The bulk of the new grains developed by increasing misorientation between the subareas of an initially polygonized old grain. There is no evidence of any marked host control on new-grain orientation, but new grain c-axis plots are generally similar to the corresponding old-grain plots from the same specimen. 相似文献
7.
The new caprinoidean rudist bivalve Cobbanicaprina bighornensis gen. nov., sp. nov. is described from the upper middle Cenomanian of Big Horn County, Montana, USA. Cobbanicaprina gen. nov. is closely related to Mexicaprina and differs from that form in the absence of an external ligamental groove. The presence of Cobbanicaprina gen. nov. in the middle Cenomanian indicates that the Caprinuloideidae did not become extinct at the top of the Albian and persisted into the Cenomanian. The presence of this specimen so far north in the Western Interior Seaway is attributed to a dried-out individual specimen having been transported post-mortem by currents. 相似文献
8.
The distinct initial fabrics of sand may give rise to dramatically different responses to the applied loading, as evidenced by numerous laboratory tests reported in the literature. In this study, both dry deposition (DD) and moist tamping (MT) methods were employed to prepare sand specimens to generate different initial fabrics. Drained tests were conducted on these specimens under pure principal stress axis rotation while keeping the principal stress components constant. The factors that may influence the deformation characteristics of sand, such as deviatoric stress q, coefficient of intermediate principal stress b, and mean principal stress p, were also taken into consideration in the tests. Test results show that the developments of three normal strain components with number of cycles are very different between DD and MT specimens, which is also closely related to the factors of q, b, and p. It is seen that DD specimen tends to generate larger contractive volumetric strains than MT specimen, which is more significant when q and b increase or p decreases. The shear stiffness of DD specimen is greater than that of MT specimen. The shear modulus ratio, Gj/G1, increases with the increase of q and b or the decrease of p, which is more prominent in DD specimen than in MT specimen. It is also shown that DD specimen appears to exhibit stronger non-coaxiality than MT specimen, in which such difference of non-coaxiality tends to decrease with the increase in number of cycles.
相似文献9.
Cheng Zhao Yimeng Zhou Qingzhao Zhang Chunfeng Zhao Hiroshi Matsuda 《国际地质力学数值与分析法杂志》2020,44(3):353-370
To deeply understand the cracking mechanical behavior of brittle rock materials, numerical simulations of a rock specimen containing a single preexisting crack were carried out by the expanded distinct element method (EDEM). Based on the analysis of crack tips and a comparison between stress- and strain-based methods, the strain strength criterion was adopted in the numerical models to simulate the crack initiation and propagation processes under uniaxial and biaxial compression. The simulation results indicated that the crack inclination angle and confining pressure had a great influence on the tensile and shear properties, peak strength, and failure behaviors, which also showed a good agreement with the experimental results. If the specimen was under uniaxial compression, it was found that the initiation stress and peak strength first decreased and then increased with an increasing inclination angle α. Regardless of the size of α, tensile cracks initiated prior to shear cracks. If α was small (such as α ≤ 30°), the tensile cracks dominated the specimen failure, the wing cracks propagated towards the direction of uniaxial compression, and the propagation of shear cracks was inhibited by the high concentration of tensile stress. In contrast, if α was large (such as α ≥ 45°), mixed cracks dominated the specimen failure, and the external loading favored the further propagation of shear cracks. Analyzing the numerical results of the specimen with a 45° inclination angle under biaxial compression, it was revealed that lateral confinement had a significant influence on the initiation sequence and the mechanical properties of new cracks. 相似文献
10.
The first specimen of Aturoidea to be recorded in East Asia has been found in the Upper Cretaceous Sada limestone in Shimanto City, Kochi Prefecture, Japan. The specimen is one of the few representatives from the Upper Cretaceous, along with species known from Libya, Angola, and India. The specimen is very similar to A. mathewsonni from the Paleocene deposits in California. However, we describe the specimen as A. cf. mathewsonni, as it slightly differs from A. mathewsonni in the shape of the lateral lobe of the suture. The finding reveals that Aturoidea had already lived in waters around East Asia in the Late Cretaceous. 相似文献
11.
A New Species of the Family Juraperlidae(Insecta:Grylloblattida)from the Middle Jurassic of China 总被引：1，自引：1，他引：0
<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
12.
洒普山虫是关杨虫(Kuanyangia)的一个亚属,乃1966年张文堂教授建立的,过去只有两个种:一个种名瘤点洒普山虫Kuanyangia(Sapushania)granulosa Chang,产于云南武定洒普山及狮子山,下寒武统筇竹寺组;另一个种名陕西洒普山虫Kuanyangia(Sapushania)shaanxiensis Zhang et Lin,产于陕西宁强坑家洞,下寒武统郭家坝组。本新种Kuanyangia(Sapushania)bella Chen(sp.nov.),产于云南昆明筇竹寺,下寒武统筇竹寺组。虽然只有一块标本,但标本保存的十分精美完好,与之共生的还有云南云南头虫Yunnanocephalus yunnanensis(Mansuy),产出层位系筇竹寺组的中上部。 相似文献
13.
云南禄丰县川街盆地中侏罗统产出弓鲛鱼类化石后甸弓鲛(Hybodus houtienensis Young)、新庄弓鲛(新种)(Hybodus xinzhuangensis Sun)、川街弓鲛(新种)(Hybodus chuanjieensis Sun)。后甸弓鲛(Hybodus houtienensis Young)是中国发现最早的弓鲛鱼类之一,正型标本为破碎的鳍棘,副型标本为一枚牙齿齿冠。依据在川街盆地相同层位发现的新化石材料,对后甸弓鲛副型标本进行了增补,补充了描述,建立了2个弓鲛新种:新庄弓鲛与川街弓鲛,丰富了"后甸弓鲛带"弓鲛类群,并讨论了弓鲛属的生物地层、生活的古环境和地理分布特征。 相似文献
14.
Use of the Boussinesq Equation for Determining the Distribution of Stress Within a Diametrical Point Load Test 总被引：1，自引：0，他引：1
Summary The maximum tensile stress at failure for a dry specimen, as determined by the Boussinesq equation for the diametrical point
load test, was found to be in very good agreement with the diametrical point load tensile strength (Is) as defined by ISRM (1985). The force at failure for specimens of different geometry was used to determine the stress distribution
along the line of loading. Distinctive tensile stress gradients dominate almost 84 percent of the specimen radius regardless
of the size of the specimen. The maximum tensile stress is located away from the centre of the specimen at a distance approximately
76 percent along the specimen radius, measured from the centre. The stress magnitude at the centre of the specimen is small
and represents about 13 percent of the maximum tensile stress calculated, which suggests that the initiation of the fracture
is not from the specimen centre. At the zone of contact between the specimen and the loading cones there exists great compressive
stress in areas where much material destruction occurs under the loading platen cones. The value of this compressive stress
varies from specimen to specimen and, for the material used in these experiments (Oolitic limestone), ranges from 5.3 to 7.2
times the dry unconfined compressive strength of the material. According to the ISRM Suggested Method for Point Load Test,
Is
(50) is approximately 0.8 times the uniaxial tensile strength. The maximum tensile stress revealed by the Boussinesq equation
(Bs) was correlated with Is
(50) and found to be in the order of 0.9 times the uniaxial tensile strength. 相似文献
15.
Hiroshi Tateyama Susumu Shimoda Toshio Sudo 《Contributions to Mineralogy and Petrology》1978,66(2):149-156
In the system Na2CO3-MgO-SiO2-H2O a new sodium magnesium silicate was synthesized under hydrothermal conditions; 450–600 ° C and 300–1000 Kg/cm2. The structure of the specimen was determined by X-ray powder methods, and its properties were studied by chemical, infrared and TG analyses. The specimen has a triple chain structure (space group, C2/c) with the ideal chemical composition, 4 (Na2Mg4Si6O16(OH)2) and lattice parameters, a= 10.152(2), b=27.137(4), c=5.276(1) Å, and = 106.97(3) °.The essential feature of the structure is shown by the presence of SiO4 tetrahedra linked to form chains which have three times the width of those in pyroxene. These triple chains have a periodicity, 5.27 Å, along their lengths, and are bonded to each other laterally by the brucite layer made up by eight Mg cations and sandwiched between two inward pointing bands of tetrahedra. These units are linked back to back by cations (Mg or Na) in the Na(2) site and by a large cation (Na) at the Na(1) site. 相似文献
16.
Diverse new material of mantises found in the Cretaceous amber-bearing deposits from Lebanon (Barremian), Spain (Albian), and Myanmar (Albian–Cenomanian) are described and figured. The Lebanese and Spanish forms are nymphs; while the one from Myanmar is an adult specimen. The Lebanese nymph corresponds to a new specimen of Burmantis lebanensis Grimaldi, 2003 while the adult Burmese (Myanmar) specimen belongs to the new species Burmantis zherikhini. The Spanish specimen represents a new genus and species and is established as Aragonimantis aenigma, but is considered family incertae sedis. The Spanish specimen is the first record of Mesozoic mantises from western-European amber deposits. A revised phylogenetic hypothesis for Cretaceous mantises is proposed. 相似文献
17.
S.P. Bennett P.M. Barrett M.E. Collinson S. Moore-Fay P.G. Davis C.P. Palmer 《Proceedings of the Geologists' Association. Geologists' Association》2012,123(1):146-154
This paper describes a new ichthyosaur specimen from the Stonebarrow Marls Member (Charmouth Mudstone Formation) of Charmouth, Dorset. It is substantially complete and various characters of the skull (snout ratios and basioccipital morphology) and appendicular skeleton (the number of digits on the hind paddle, which can be used to infer the number of digits on the front paddle) indicate that the specimen is referable to Ichthyosaurus communis. This provides the first direct evidence for the presence of I. communis in the Pliensbachian, extending the stratigraphic range of the species. The specimen also preserves a probable gullet content, which demonstrates that fish formed part of the diet of this individual. 相似文献
18.
Yangtzedonta is Undoubtedly a Junior Synonym of Xianfengella 总被引：3，自引：0，他引：3
QIAN Yi Nanjing Institute of Geology Palaeontology Chinese Academy of Sciences Nanjing Jiangsu 《《地质学报》英文版》2005,79(6):777-777
With the verification of the type specimen by six experts from the Nanjing Institute of Geology and Palaeontology, the specimen of Xianfengella prima He and Yang, 1982 described by Qian （Qian, 2001, flge2： la-c） is confirmed to be the holotype specimen （NIGP. 84430） of Yangtzedonta primitiva Yu, 1985, and consequently, Yu Wen＇s view that they are not the same specimen is impractical. This fact demonstrates that Yangtzedonta primitiva Yu, 1985 is undoubtedly a junior synonym of Xianftngella prima He and Yang, 1982, and is invalid. Qian＇s conclusion （Qian, 2001 ） that no bivalve appeared in the early Meishucunian Stage of the Early Cambrian is rational. 相似文献
19.
<正>A new specimen assigned to the species Iverya averyi gen.nov.and sp.nov.is described.This species is considered as a triadotypomorphan insect,a poorly known group of Triassic stem-odonatans.Like other triadotypomorphans,this species exhibits an area between MA and MP that is comparatively broad,and a cubitoanal area involving an AA stem distinct from CuA+CuP+AA emitting several posterior branches.Diagnostic character states of the new species are listed.Although incomplete,the specimen provides new information on the wing morphology of triadotypomorphans.This discovery might contribute to better assessment of the phylogenetic position of triadotypomorphan species with respect to other stem-odonatans. 相似文献