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1. chinaXiv:201708.00176 [pdf]


分类: 生物学 >> 生物医药


提交时间: 2017-08-08 点击量264, 下载量53

2. chinaXiv:201708.00174 [pdf]

Analytical solutions to single scattering of SH waves by a cylindrical fiber with radially gradient interphases

章俊; 刘炼; 曾龙海; 鲍家定
分类: 力学 >> 基础力学

In this work, analytical solutions to the single scattering of SH waves by a cylindrical fiber with two specific radially gradient interphase layers are supported based on the method proposed by P.A. Martin (Martin 2002, JASA). In the first case, 1) shear modulus μ(r)=e^2βrand the square of wave number, k^2 , is a linear function of 1/r, and 2) μ(r)=e^(-βr^2 ) and k^2 is a linear function of r^2. For example, analytical solutions to single scattering of SH waves by a Sic fiber with the above two interphase layers embedded in aluminum are presented. The calculated scattering cross sections are compared with values obtained from an approximate method (dividing the continuous varying layer into multiple homogeneous sub-layers). The two methods yield similar results. The contribution of this work benefits the validation of various numerical methods used in the inhomogeneous media.

提交时间: 2017-08-08 点击量69, 下载量53

3. chinaXiv:201708.00173 [pdf]

Viviparity in a Triassic marine archosauromorph reptile

LI Chun; Olivier RIEPPEL; Nicholas C. FRASER
分类: 地球科学 >> 地质学

Eggs or embryos have been reported in various groups of fossil reptiles, where viviparity is a common mode of reproduction in aquatic taxa such as the ichthyopterygians, some groups of sauropterygians, mosasauroids, some taxa of choristoderans and certain protorosaurs.Here, we describe a complete embryo of a marine protorosaur, based on a well-preserved, curledup skeleton. The new discovery is referred to a taxon closely related to the remarkable longnecked Dinocephalosaurus. It further confirmed viviparity in an archosauromorph group and indicates an increasing taxonomic diversity not only within this group, but of Triassic marine reptiles in general.

提交时间: 2017-08-08 来自合作期刊:《古脊椎动物学报》 点击量16, 下载量16

4. chinaXiv:201708.00172 [pdf]

New material of the Early Pleistocene mammalian fauna from Chutoulang, Chifeng, eastern Nei Mongol, China and binary faunal similarity analyses

DONG Wei; ZHANG Li-Min; LIU Wen-Hui
分类: 地球科学 >> 地质学

New specimens from a new locality at Chutoulang in eastern Nei Mongol were identifed as Canis chihliensis, Coelodonta nihowanensis, Hipparion (Proboscidipparion) sinense,Equus sanmeniensis, Sus lydekkeri, Muntiacus cf. M. lacustris, Axis shansius, Eucladoceros boulei, Spirocerus cf. S. wongi and Bison palaeosinensis. They enriched the mammalian fauna of Chutoulang to 30 taxa together with the material from Dongliang, Dongcun Beigou and Dongcun Nangou localities. The mammalian fossils from these four localities are all from the same horizon and can be regarded as the same fauna, i.e. Chutoulang fauna. The composition of Chutoulang fauna is the closest to that of Nihewan (s.s.) by binary faunal similarity coeffcients. The age of Chutoulang fauna is between those of Nihewan (s.s.) and Juyuandong at Liucheng according to Brainerd-Robinson’s sequence, extinction rates and antiquity coeffcients. The numerical age of Chutoulang fauna is estimated between 1.4–1.6 Ma based on those of compared faunas. Carnivora are the most numerous in Chutoulang fauna with 11 taxa, but mostly the small sized ones.Perissodactyla and Artiodactyla make about half of the fauna. They are mostly large sized forms. The presence of numerous browsers or forest dwellers implies the existence of forest or woodland in Chutoulang area during that period. The presence of grazers and openland dwellers indicates the existence of larger area of grassland or steppes than that of woodland or forests. Most members of Chutoulang fauna are temperate habitat dwellers with a few cold-prone forms such as Ochotona and Coelodonta. The climate in Chutoulang area in the Early Pleistocene was thus similar to that of today. Chutoulang fauna is the most northeastern Early Pleistocene fauna in China and it can be recommended as a type site of the Early Pleistocene mammalian fauna in northeastern China.

提交时间: 2017-08-08 来自合作期刊:《古脊椎动物学报》 点击量18, 下载量16

5. chinaXiv:201708.00171 [pdf]

Early Middle Jurassic dinosaur footprints from Zizhou County, Shaanxi, China

LI Yong-Xiang; ZHANG Yun-Xiang
分类: 地球科学 >> 地质学

Four types of footprints of carnivorous dinosaurs have been found from the Yan’an Formation of early Middle Jurassic in Zizhou County, Shaanxi, China. From the top to bottom interval, the four types of footprints discovered at five layers in a 1.7 m thick stratum are as follows: 1) the large tridactyl footprints in the fifth layer (e, top) belong to Zizhoupus wangi ichnogen. et ichnosp. nov.; 2) the medium tridactyl footprints in the third and fourth layers (c–d) belong to Changpeipus longweimaoensis ichnosp. nov.; 3) small tridactyl or tetradactyl footprints in the second layer (b) belong to Shensipus xiaoliheensis ichnosp. nov. and 4) small tridactyl footprints in the frst layer (a, bottom) belong to Shensipus tungchuanensis.

提交时间: 2017-08-08 来自合作期刊:《古脊椎动物学报》 点击量25, 下载量20

6. chinaXiv:201708.00170 [pdf]

Early Mammut from the Upper Miocene of northern China, and its implications for the evolution and differentiation of Mammutidae

WANG Shi-Qi; LI Yu; Jaroon DUANGKRAYOM; CHEN Shao-Kun; HE Wen; CHEN Shan-Qin
分类: 地球科学 >> 地质学

Mammut is the terminal taxon of the proboscidean group Mammutidae, which survived to the Late Pleistocene. Although this genus was widely distributed in the Pliocene of Eurasia and the Pleistocene of North America, little is known about its early evolution. Here, we report on Mammut cf. M. obliquelophus from the Upper Miocene of northern China based on new fossil material, including an almost complete juvenile cranium and other remains, which show many primitive features within Mammutidae and clearly demonstrate the morphological evolution of Mammut. The strongly laterally expanded lateral wing of the occiput and the presence of basal constriction of the incisive fossa display cranial similarity between Mammut cf. M. obliquelophus and both Eozygodon morotoensis and Choerolophodon guangheensis, early representatives of the Mammutidae and Choerolophodontidae, respectively, indicating the close relationship between these two groups: both of them are located at the basal phylogenetic positions in Elephantimorpha.This result is further confrmed by a cladistic analysis.

提交时间: 2017-08-08 来自合作期刊:《古脊椎动物学报》 点击量26, 下载量22

7. chinaXiv:201708.00169 [pdf]

Cyprinus-like pharyngeal bones and teeth (Teleostei, Cypriniformes, Cyprinidae) from the Early–Middle Oligocene deposits of South China

CHEN Geng-Jiao; CEN Li-Di; LIU Juan
分类: 地球科学 >> 地质学

Here we describe †Nanningocyprinus wui gen. et sp. nov, a fossil Cyprinus-like fsh from the Early-Middle Oligocene deposits of Langdong, Nanning Basin, Guangxi Province,South China. †Nanningocyprinus wui is represented by a number of pharyngeal bones and teeth.It differs from all other cyprinid fishes in the following character combination: tooth formula—3·2·1, crushing molar-like A1 much larger than A2, only one groove on the grinding surface of A2 and B1 respectively, and the anterior angle of the pharyngeal bone triangular and prominent.The new-found Cyprinus-like fsh, along with the previously known Late Eocene †Eoprocypris maomingensis (Procypris-like) and Oligocene †Huashancyprinus robustispinus (Cyprinus-like)from South China, further indicates an early branching and diversification of the Cyprininae(Cyprinidae) in this area

提交时间: 2017-08-08 来自合作期刊:《古脊椎动物学报》 点击量8, 下载量8

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