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71.
Sauropod dinosaurs are poorly represented in the Lower Cretaceous of eastern Asia. Here, we describe a number of isolated sauropod teeth from the Kuwajima Formation (?Berriasian–?Hauterivian) of Shiramine, Japan. The mosaic of shared derived characters and symplesiomorphies displayed by the teeth indicate that they are referable to a basal member of the titanosauriform radiation. A taxonomic review of previously described sauropod specimens from eastern and south–eastern Asia reveals that a diversity of sauropods (including a titanosaurian, a basal titanosauriform and a ?euhelopodid, as well as several forms of indeterminate systematic position) was present in this region in the Early Cretaceous. This diversity conflicts with previous suggestions that eastern Asia was biogeographically isolated from the rest of Laurasia until the late Early Cretaceous and that the sauropod fauna was limited to the endemic East Asian clade Euhelopodidae. The presence of titanosauriform sauropods in the basal Cretaceous of Japan and Thailand indicate that the proposed faunal isolation of eastern Asia ended approximately 20 myr earlier than usually suggested.  相似文献   
72.
Two new dinosaur tracksites are reported from the Lower Cretaceous Jiaguan Formation in the Sichuan Basin, Qijiang District of Chongqing. These are the Gaoqing-Yongsheng and the Huibu tracksites, which represent the 13th and 14th reports from this formation. The Gaoqing-Yongsheng tracksite reveals the trackway of a large biped (ornithopod) in association with isolated sauropod tracks and large indeterminate undertracks with radial cracks. These features are preserved as natural casts with pebble infillings in a coarse, cross bedded and very thick bedded sandstone sequence. The Huibu tracksite reveals isolated theropod tracks and ornithopod tracks, the latter having a quadripartite, Caririchnium-like morphology, preserved in a thin bedded sandstone sequence with intercalated mudstone.  相似文献   
73.
在孤峰组底部发现了包括Mesogondolella nankingensis在内的牙形刺动物群。Gondolella serrata Clark et Ethington,1962是Mesogondolella nankingensis(Jin,1960)的同义名,Mesogondolella nankingensis已被北美学者推荐为瓜达洛坪统底界的标志化石。因Mesogondolella na  相似文献   
74.
记述中蝎蛉科Mesopanorpodidae 4属4种,其中包括3新属4新种:Longifurcula hejiafangensi gen.et sp.nov,Ladinochorista lata gen.et sp.nov.,Allochorista erdosensis gen.et sp.nov.,Itaphlebia tongchuanensis sp.nov..化石标本采自陕西铜川中三叠统铜川组下段上部的灰绿色泥岩和页岩.这些新属、种系陕西昆虫群铜川昆虫组合的新成员(属陕西动物群、陕西生物群的一个类别).根据前人的植物、孢子、双壳、叶肢介、介形虫、昆虫化石等的研究结果,铜川组的时代划归中三叠世,相当于欧洲中三叠世拉丁尼期(Ladinian stage).  相似文献   
75.
再论假裸枝叠层石科*   总被引:4,自引:1,他引:4  
内蒙古桌子山地区中奥陶统公乌素组遗迹化石十分丰富.本文共鉴定、描述14个遗迹属、17个遗迹种,其中1新遗迹属——Biscopulatichnus、4新遗种和6未定种.并根据不同遗迹属在不同层位中的相对丰度,建立了4个遗迹组合,自下而上的顺序是:1. Taenidium-Phycodes 组合;2. Volkichnium 组合;3. Helminthopsis 组合;4. Granularia-Circulichnus 组合,大致相当于 Seilacher (1967) 的 Zoophycos 遗迹相,反映出公乌素组沉积期,水体较深且宁静、缺氧、有机质含量高,推测应为大陆斜坡环境.  相似文献   
76.
The oldest Foliomena fauna was, until now, known from the middle–upper Miaopo Formation (Nemagraptus gracilis Biozone, lower Sandbian, basal Upper Ordovician) of South China. In this study, the oldest record of the fauna is set back to the latest Darriwilian (upper Hustedograptus teretiusculus Biozone), represented by Foliomena jielingensis and some typical constituents of the Foliomena fauna from the basal Miaopo Formation at Jieling, northern Yichang, western Hubei Province, central China. The Miaopo Formation is characterized by its organic‐rich dark‐grey shale facies, unique in its localized distribution on the Yangtze Platform, and distinguished by its rich and diverse benthic and graptolitic faunas. This suggests an origin of the Foliomena fauna in periodically oxygen‐starved local depressions on the Yangtze Platform during the Middle–Late Ordovician transition.  相似文献   
77.
首次在新疆塔里木盆地塔中地区中2井上奥陶统良里塔格组礁岩中发现保存精美的牙形刺化石,包括6属13种和未定种,含一个新亚种Belodina longxianensis minor subsp.nov.。根据牙形刺化石确定,良里塔格组上部属于上奥陶统中部的Belodina confluens带。中2井良里塔格组第2—4层生物礁发育的精确时代是Belodina confluens带。  相似文献   
78.
The metal ion complexing properties of the ligand HQC (8-hydroxyquinoline-2-carboxylic acid) are reported. The structures of [Zn(HQCH)2] · 3H2O (1) and [Cd(HQCH)2] · 3H2O (2) were determined (HQCH = HQC with phenol protonated). Both 1 and 2 are triclinic, space group , with Z = 2. For 1 a = 7.152(3), b = 9.227(4), c = 15.629(7) Å,  = 103.978(7)°, β = 94.896(7)°, γ = 108.033(8)°, R = 0.0499. For 2 a = 7.0897(5), b = 9.1674(7), c = 16.0672(11) Å,  = 105.0240(10)°, β = 93.9910(10)°, γ = 107.1270(10)°, R = 0.0330. In 1 the Zn has a distorted octahedral coordination geometry, with Zn–N of 2.00 and 2.15 Å, and Zn–O to the protonated phenolic oxygens of 2.431 and 2.220 Å. The structure of 2 is similar, with Cd–N bonds of 2.220 and 2.228 Å, with Cd–O bonds to the protonated phenolate oxygens of 2.334 and 2.463 Å. The structures of 1 and 2, and isomorphous Ni(II) and Co(II) HQC complexes reported in the literature, show very interesting short (<2.5 Å) O–O distances in H-bonds involving the protons on the coordinated phenolates and lattice water molecules. These are discussed in relation to the possible role of short low-energy H-bonds in alcohol dehydrogenase in mediating the transfer of the hydroxyl proton of the alcohol to an adjacent serine oxygen.

The formation constants for HQC are determined by UV–Visible spectroscopy at 25 °C in 0.1 M NaClO4 with Mg(II), Ca(II), Sr(II), Ba(II), La(III), Gd(III), Zn(II), Cd(II), Ni(II), Cu(II), and Pb(II). These show greatest stabilization with metal ions with an ionic radius above 1.0 Å. This is as would be expected from the fact that HQC forms two five-membered chelate rings on complex-formation, which favors larger metal ions. The ligand design concept of using rigid aromatic backbones in ligands to achieve high levels of preorganization, and hence the high log K values (for a tridentate ligand) and strong metal ion selectivities observed for HQC, is discussed.  相似文献   

79.
Macroborings provide detailed information on the bioerosion, accretion and palaeoenvironment of both modern and fossil reefs. Dolomitized reefal carbonates in the Um Mahara Formation exhibit an outstanding example of spatially distributed, well‐preserved bioerosion structures in tropical to subtropical syn‐rift Miocene reefs. Ten ichnospecies belonging to five ichnogenera are identified; three belonging to the bivalve‐boring ichnogenus Gastrochaenolites, three attributed to the sponge‐boring ichnogenus Entobia, and four ichnospecies assigned to three worm‐boring ichnogenera Trypanites, Maeandropolydora and Caulostrepsis. The distribution of the reported borings is strongly linked to the palaeo‐reef zones. Two distinctive ichnological boring assemblages are recognized. The Gastrochaenolites‐dominated assemblage reflects shallower‐marine conditions, under water depths of a few metres, mostly in back‐reef to patch‐reef zones of a back‐reef lagoon. The Entobia‐dominated assemblage signifies relatively deeper marine conditions, mostly in reef core of the fringing Miocene reefs. These ichnological assemblages are attributed herein to the Entobia sub‐ichnofacies of the Trypanites ichnofacies. This ichnofacies indicates boring in hard carbonate substrates (such as corals, rhodoliths, carbonate cements and hardgrounds) during periods of non‐sedimentation or reduced sediment input.  相似文献   
80.
陕西镇巴早寒武世海绵骨针化石   总被引:1,自引:0,他引:1  
作者对采自陕西省镇巴县下寒武统西蒿坪段和水井沱组下部碳酸盐岩地层的海绵骨针化石进行了研究。三叶虫及小壳化石的生物地层学资料表明西蒿坪段和水井沱组下段属于筇竹寺阶。化石经室内醋酸浸泡处理后获得,骨针化石保存较好、类型多样,其中属于六射海绵纲的骨针3类,普通海绵纲的骨针6类,分类未定的骨针1类(Nabaviellasp.);并详细地对各类骨针化石进行了描述。虽然普通海绵骨针类型多样,但六射海绵的骨针丰度远高于普通海绵。简要地探讨了海绵骨针的保存方式,对比和分析了西蒿坪段和水井沱组海绵骨针化石组成的差异。结合同时代产自皖南荷塘组和云南澄江动物群中特异保存的海绵软躯体化石资料,认为虽然海绵动物起源于新元古代末期,但躯体海绵化石和骨针化石都显示海绵动物的大辐射事件发生在早寒武世筇竹寺期。  相似文献   
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