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1.
最近辽西建昌地区报道发现了一系列带羽毛恐龙和翼龙化石, 其赋存化石的地层层位时代一直富有争议。我们结合前人资料对玲珑塔含化石地层剖面进行了野外调查和实测, 厘定了含化石地层沉积层序和时代归属。剖面顶底岩石组合特征主要以溢流相中性熔岩和近火山口相火山碎屑岩为主, 中间层位为河流相-湖泊相碎屑岩。该剖面产有大量叶肢介、介形类、双壳类、昆虫、鱼类、植物化石和大量脊椎动物化石。上述化石指示含恐龙化石地层时代为中侏罗世。通过区域对比认为含恐龙化石地层与区域上髫髻山组地层层序和岩石组合相似, 因此认为含恐龙化石地层为中侏罗世髫髻山组(火山岩同位素年代学年龄范围为152~165 Ma)。 相似文献
2.
An Important Ornithischian Tracksite in the Early Jurassic of the Shenmu Region,Shaanxi, China 总被引：1，自引：0，他引：1
LI Jianjun Martin G. LOCKLEY ZHANG Yuguang HU Songmei MATSUKAWA Masaki BAI Zhiqiang 《《地质学报》英文版》2012,86(1):1-10
A large track site with multiple,well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia,herein named Shenmuichnu... 相似文献
3.
颗石藻是海洋中广泛分布的超微型浮游藻,经生物矿化作用形成的碳酸钙质颗石,在古海洋学研究中具有重要意义。海洋粘土矿物与有机质的有机-无机相互作用在全球碳循环中扮演着重要角色。本文选取广泛分布于海洋的赫氏颗石藻Emiliania huxleyi与海洋粘土矿物中具有代表性的伊利石和蒙脱石共培养。通过对颗石藻生长曲线和Sr/Ca、Mg/Ca元素比值、颗石藻与粘土矿物样品的紫外可见光吸收光谱、红外吸收光谱和矿物物相等分析,研究海洋粘土矿物与颗石藻的相互作用规律。通过研究表明伊利石对颗石藻的影响较小,蒙脱石因对营养元素的吸附和颗石藻的絮凝作用对颗石藻的生长和Sr/Ca、Mg/Ca元素比值影响较大。颗石藻代谢分泌的生物分子未能通过层间插层作用进入伊利石层间,颗石藻分泌的生物分子可通过插层作用进入并储存于蒙脱石层间,海洋粘土矿物中的蒙脱石与海洋微生物的相互作用值得地球微生物家关注,可能有助于对古海洋环境的认识。 相似文献
4.
ZHENG Tingting BAI Yi WANG Qiang ZHU Xufeng FANG Kaiyong YAO Yuan ZHAO Yongqiang WANG Xiaolin 《《地质学报》英文版》2018,92(3):897-903
A new ootype collected from the Upper Cretaceous Lijiacun Formation in the Shangdan Basin, Shaanxi Province is described in this paper. Based on general external shape, size, eggshell thickness and honeycomb‐like eggshell microstructure, eggs are referable to the oofamily Faveoloolithidae. Compared with other members of Faveoloolithidae, specimens described in this paper show special characteristics: adjacent pores are usually separated by two eggshell units between which often develop interspaces; columnar eggshell units are relatively closely arranged in radial view. According to these characteristics, we erect a new oogenus and a new oospecies: Duovallumoolithus shangdanensis oogen. et oosp. nov. The new discovery expands the diversity of Faveoloolithidae. 相似文献
5.
The dentary diastema of iguanodontians has been considered to be related to its unique jaw mechanism for herbivorous adaptation. The dentary and diastema lengths of iguanodontians were measured and compared to elucidate the evolution of iguanodontian diastema. A gap in ratios between most non-hadrosaurid iguanodontians and hadrosaurids was observed, suggesting that all non-hadrosaurid iguanodontians, expect for Ouranosaurus nigeriensis and Protohadros byrdi, lack a diastema or have a short diastema, although some other taxa have been considered to have a long diastema in previous studies. In non-hadrosaurid iguanodontians, some large-sized forms, such as Iguanodon bernissartensis, Shuangmiaosaurus gilmorei, and possibly Eolambia caroljonesa, had a short diastema through ontogeny, whereas Ouranosaurus nigeriensis and Protohadros byrdi developed a long diastema convergently. The development of a long diastema of hadrosaurine hadrosaurids may be different from that of lambeosaurine hadrosaurids. Some hadrosaurines (Edmontosaurus annectens, Edmontosaurus regalis, and Saurolophus angustirostris) may have developed a long diastema in the subadult stage and showed little elongation of dentary diastema through ontogeny. Lambeosaurines (Corythosaurus casuarius and Lambeosaurus lambei) tend to have a short diastema in the embryonic and subadult stages, and an elongated diastema from the subadult to adult stages. 相似文献
6.
Tail anatomy of unenlagiid theropods remains poorly known. The most complete and informative taxon of this family is Buitreraptor gonzalezorum from the Upper Cretaceous of Rio Negro province, Argentina. The aim of the present contribution is to carry out an analysis of the tail anatomy of Buitreraptor based on its holotype and a newly collected specimen as well. Similarities shared by Buitreraptor, Rahonavis, Anchiornis and Archaeopteryx include: mid-caudal vertebrae with postzygapophyses longer than prezygapophyses, and mid-caudal centra with a system of lateral laminae and concavities. Preservation of paravian skeletons, as well as muscular reconstruction, indicate the presence of two different functional sections of the tail. This contribution sheds light on paravian tail evolution and provides new data on tail changes that occurred along the theropod line towards modern birds. 相似文献
7.
A new theropod dinosaur, Shidaisaurus jinae gen. et sp. nov., has been described on the basis of an incomplete skeleton. The specimen was found near the base of the Upper Lufeng Formation (early Middle Jurassic) in Yunnan, China. It is the first theropod dinosaur from the Middle Jurassic of Yunnan. Shidaisaurus jinae is distinguishable from other Jurassic theropods by certain features from the braincase, axis, and pelvic girdle. The absence of any pleurocoels in the axis or in any anterior dorsal vertebrae suggests that the new Lufeng theropod is relatively primitive and more plesiomorphic than most of the Middle to Late Jurassic theropods from China. Most Chinese taxa of Jurassic theropod dinosaurs have not been well described; a further detailed study will be necessary for us to determine their phylogenetic relationships with Shidaisaurus jinae. 相似文献
8.
The coccolithophore Emiliania huxleyi was grown in seawater under different Ba concentrations. The relationship of coccolith Ba/Ca ratio and seawater Ba/Ca ratio was found to be linear. The linear regression yields the apparent Ba exchange coefficient of 0.10. Our data support a recently proposed generic model (Langer G., Gussone N., Nehrke G., Riebesell U., Eisenhauer A., Kuhnert H., Rost B., Trimborn S., and Thoms S. (2006) Coccolith strontium to calcium ratios in Emiliania huxleyi: the dependence on seawater strontium and calcium concentrations. Limnol. Oceanogr.51, 310-320.) developed for explaining apparent exchange coefficients of metabolically inert divalent trace metals, such as Sr, in E. huxleyi. This model represents the first approach combining cell physiological processes and data from inorganic precipitation experiments, which quantitatively explains coccolith apparent Sr and Ba exchange coefficients. 相似文献
9.
A New Troodontid Dinosaur from the Lower Cretaceous Yixian Formation of Liaoning Province, China 总被引：1，自引：1，他引：0
SHEN Caizhi Lü Junchang LIU Sizhao Martin KUNDRáT Stephen L. BRUSATTE GAO Hailong 《《地质学报》英文版》2017,91(3):763-780
A new troodontid dinosaur,Daliansaurus liaoningensis gen.et sp.nov.,is erected based on a nearly complete specimen from the Lower Cretaceous Yixian Formation of Beipiao City,Liaoning Province,China.This well preserved skeleton provides important new details of the anatomy for Liaoning troodontids,and gives new insight into their phylogenetic relationships and evolution.Daliansaurus is distinguished from other troodontids by an enlarged ungual on pedal digit IV,which is approximately the same size as the sickle-shaped second ungual,and is differentiated from other Liaoning troodontids by a number of characters of the skull,manus,pelvis,and hindlimb.A phylogenetic analysis recovers Daliansaurus within a subclade of Liaoning troodontids that also includes Sinovenator,Sinusonasus,and Mei.We erect a name for this group—Sinovenatorinae—and argue that it reflects a localized radiation of small-bodied troodontids in the Early Cretaceous of eastern Asia,similar to previously recognized radiations of Liaoning dromaeosaurids and avialans.As more Liaoning theropods are discovered,it is becoming apparent that small,feathered paravians were particularly diverse during the Early Cretaceous,and future work is needed to clarify how this diversity arose,which species coexisted,and how these numerous species partitioned niches. 相似文献
10.
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11.
We here report the discovery of unusual distributions of long-chain alkenones (C37-C42) in two Cretaceous black shales from the Blake-Bahama Basin, western North Atlantic. These sediments are Cenomanian (c. 95 Ma) and mid-Albian (c. 105 Ma) in age, thus significantly extending the geological range of these compounds. The precise source of these lipids is, as yet, unknown, although they may derive from an ancient ancestor of Emiliania huxleyi. 相似文献
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13.
Y. L. Chen J. Ni W. Shao Y. C. Zhou A. Javadi R. Azzam 《Rock Mechanics and Rock Engineering》2012,45(2):241-249
In this paper, white Portland cement was used as an experimental material. Prismatic specimens with pre-existing flaws at
different angles of inclination (α) varying through 0°, 30°, 45°, 60°, 75° to 90° and cylindrical specimens with different numbers of pre-existing flaws (n) varying through 0, 1, 2 to 3 were tested under uni-axial compression tests. Crack initiation, propagation, coalescence,
and failure were observed. The corresponding analytical expression for the stress intensity factor under uni-axial compression
was derived, the coefficient of friction and the stress intensity factor of the specimens on the surfaces of the crack were
analysed, and the corrective coefficient for the stress intensity factor was introduced. Fatigue tests with a loading frequency
of f = 100 Hz were carried out on cylindrical specimens with constant amplitude of the cyclic load which is a proportion of the
compressive load at failure (F
f) obtained from the uni-axial compression tests. The fatigue property of the specimens was analysed and the relationship (S
max − lg N
f) between the maximum stress and the number of loading cycles at failure for specimens with pre-existing flaws was proposed.
The effect of pre-existing flaws on the fatigue life (N
f) and dynamic load (S
D) which can be applied was investigated. 相似文献
14.
The Upper Cretaceous Prairie Canyon Member of the Mancos Shale, Book Cliffs, Utah, contain outstanding examples of prodeltaic turbidity and hyperpycnal flow deposits. Sandstone‐rich, heterolithic and mudstone‐rich channel fills occur near the north‐west entrance to Tusher Canyon, Gunnison Butte and Bootlegger Wash. Mudstone‐rich and heterolithic‐rich hyperpycnal channel deposits are mostly unbioturbated, locally displaying a few specimens of Phycosiphon incertum, Protovirgularia dichotoma, Rosselia socialis, Schaubcylindrichnus coronus and Palaeophycus tubularis. Sandstone‐rich channel deposits consist of wave‐reworked turbidites and hyperpycnites, containing Helminthoidichnites tenuis, Lockeia siliquaria, Phycodes isp., Phycosiphon incertum, Protovirgularia dichotoma, Rosselia socialis, Skolithos linearis and Fugichnia. Scolicia isp. and Chondrites isp. occur locally. Strata along the south‐west entrance of Tusher Canyon record deposition in a prodelta turbidite lobe, but far from its axis. With the exception of a few specimens of Ophiomorpha isp., bioturbation is restricted to the top of the succession, where Curvolithus simplex, Gyrochorte comosa, Lockeia siliquaria, Palaeophycus tubularis and Ptychoplasma excelsum occur. Strata at Hatch Mesa record deposition in a hyperpycnal lobe, near to its axis. Sandstone beds include Curvolithus simplex, Gyrochorte comosa, Ophiomorpha nodosa, Palaeophycus tubularis, Phycosiphon incertum, Protovirgularia dichotoma, Ptychoplasma excelsum, Schaubcylindrichnus freyi, Skolithos linearis, large specimens of Rosselia socialis and indeterminate crustacean burrows. Chondrites isp. is present in the mudstone. High rates of both episodic and sustained sedimentation, degree of substrate consolidation, freshwater discharge and water turbidity are the most important stress factors in both channels and lobes. Taxonomic composition, uneven distribution of bioturbation through the successions, and overall low ichnodiversity help to distinguish these prodeltaic deposits from bathymetrically equivalent offshore strata in the same basin. Hyperpycnal flow deposits are formed in a wide variety of environmental settings, therefore displaying high ichnological variability. Such variability is summarized by characterising ichnofaunas from four different depositional settings: (i) lakes; (ii) shelf deltas; (iii) shelf‐edge deltas; and (iv) deep‐marine systems. 相似文献
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17.
Debahuti Mukherjee 《Journal of the Geological Society of India》2010,76(3):267-274
The Bathonian sediments of the Jaisalmer Basin, India host a terebratulide brachiopod Plectoidothyris which has been previously known from the Bajocian rocks of the Boreal Province. The sharp and prominent plication of the
anterior commissure and increased length of costae separates the Jaisalmer specimens from other known species of the genus
and the population represents an endemic species — Plectoidothyris jaisalmerensis. The population was only cursorily described earlier lacking in details of precise stratigraphic control and was wrongly
assigned to a different genus. The present study is based on a large number of specimens from different localities with precise
stratigraphic data, coupled with this some recent findings of time-diagnostic ammonites have helped determine the Plectoidothyris jaisalmerensis duration in the Jaisalmer Basin as the Late Bathonian. Presence of lower Jurassic Boreal brachiopod genera in the Middle
Jurassic rocks of Ethiopian and Indo — Madagascan biogeographic provinces has been noticed earlier whereto Plectoidothyris is a new addition while it is also the first report of the genus from the Jurassic of India. The brachiopod migrations from
the north to south of the Tethys provide evidences for opening of shallow water routes in the Tethyan seaway and are probably
indicative of warmer water conditions in the Indo-Madagascan and African areas during the Middle Jurassic. 相似文献
18.
Eighty-two palaeomagnetic samples of calcareous and jaspilitic grainstones (iron-formation or ‘taconite’) and chert carbonate were collected from the 1.88-Ga Gunflint Formation at 22 sites in the Thunder Bay area, Ontario. Twenty clasts of Gunflint taconite also were sampled from the basal conglomerate of the overlying Mesoproterozoic Sibley Group. Anisotropy of magnetic susceptibility measurements indicate the Gunflint Formation in the sampling area has not experienced regional dynamic metamorphism. Analyses by variable-field translation balance and X-ray diffraction show that the predominant magnetic mineral is hematite but a small amount of magnetite also is present in some samples. Altogether, 213 Gunflint specimens and 59 Sibley conglomerate specimens were subjected to stepwise thermal demagnetisation and 74 Gunflint specimens to stepwise alternating-frequency demagnetisation. The following components were isolated for the taconites:
- • Gunflint magnetite: normal declination D=293.4°, inclination I=30.8°, α95=7.2°, n=21; reverse D=86.7°, I=–54.6°, α95=5.8°, n=29.
- • Gunflint hematite: normal D=243.6°, I=23.6°, α95=6.0°, n=11; reverse D=70.3°, I=–51.4°, α95=3.2°, n=79.
- • Sibley clasts magnetite: normal D=282.7°, I=33.4°, α95=7.6°, n=20.
- • Sibley clasts hematite: normal D=254.5°, I=56.2°, α95=8.4°, n=13; reverse D=110.6°, I=–55.7°, α95=8.3°, n=11.
19.
Pseudoemiliana lacunosa, Gephyrocapsa oceanica and Emiliania huxleyi (Ionian) (Pleistocene–Holocene) calcareous nannoplankton zones were identified from 82 samples of 14 cores taken from 8 locations in the northeastern Sea of Marmara. The investigation indicates that the identified biozones have been alternated by tectonic activity in the 1, 5 and 6 core locations. The study area has been affected three times by tectonic activity during the Pleistocene–Holocene time interval. The first activity occured during the Early Pleistocene and the others during Holocene. 相似文献