混鱼龙（爬行动物：鱼龙类）在云南罗平中三叠统的发现   总被引：3，自引：0，他引：3  

陈孝红  程龙 《地质学报》2009,83(9):1214-1220

本文首次报导和系统描述了在云南罗平中三叠统关岭组上部发现的混鱼龙Mixosaurus kuhnschnyderi Brimkmann, 1998,并与国内外同期地层中已知的混鱼龙种进行了比较。此外,还简单介绍了该鱼龙化石在云南罗平一带中三叠统发现的生物学、地层学和生物古地理分区意义。  相似文献   

十足目节肢动物化石在关岭生物群的发现     

黄金元  胡世学  文芠  张启跃  周长勇  谢韬 《地质通报》2017,36(8):1330-1333

云南罗平岔江新江底村发现的十足目节肢动物化石产出于三叠统卡尼阶小凹组,是十足目化石在关岭生物群的首次发现,也是此类化石在中国上三叠统中首次报道。此发现增加了关岭生物群的多样性,为今后在中国三叠纪其他特异埋藏化石库中寻找更多的十足目节肢动物化石提供了新的线索。  相似文献   

黄土高原沟壑区苹果基地退果还耕的生态水分效应   总被引：2，自引：1，他引：1  

何福红  蒋卫国  黄明斌 《地理研究》2010,29(10):1863-1869

近年来,黄土高原沟壑区许多果园已经退化,需要重新退果还耕,但其生态水分效应尚不明了。以陕西长武县王东沟小流域典型果园为对象,选取了盛果期果园、退化果园和退果还耕等3种土地利用方式,分析1986、2002和2009年三期土壤水分数据,研究退化果园还耕的生态水分效应。结果表明:退化果园和退果还耕地的平均含水量和土壤储水量显著高于同期的盛果期果园。果园退化后废弃和退果还耕,土壤水分会得到部分恢复。当土地利用从盛果期果园变化为耕地后,在200~600cm土层,其土壤平均含水量(10.62%)显著高于盛果期果园(8.53%)。生物利用型土壤干层仍然是盛果期果园、退化果园和退果还耕地尚待急需解决的严重的生态问题。  相似文献   

晚中生代地球表层重大地质事件的陆地环境剧变与生物群演替响应   总被引：3，自引：1，他引：2       下载免费PDF全文

柳永清  旷红伟  姬书安  吕君昌  刘燕学  江小均  彭楠  陈铭培  李家华 《地学前缘》2009,16(5)

晚中生代时期华北东北部发育燕辽生物群、热河生物群和阜新生物群陆地生物群。它们的快速演变过程和华北克拉通上同时期发育的岩石圈减薄、大面积强烈岩浆活动、变质核杂岩及伴随的伸展盆地等地球表层重大地质事件并行发生,表现着地壳表层系统圈层间的相互作用和响应。生物群的繁盛与灭绝与地球表层大规模岩浆-火山活动(髫髻山组—张家口组和大北沟组—义县组)发育时代高度协同一致。地球表层重大地质事件直接或间接地控制或改造着地球表层古地理和古生态环境,生物群只得调整自身去适应环境和生态背景的改变。火山-岩浆活动改变着地质-生态环境,生物群都紧密联系多期次火山-岩浆活动,化石也都被埋葬在沉积-火山碎屑岩中。华北克拉通破坏重大地质事件发生响应于全球变化和统一地球表层系统。盆地沉积充填序列、特殊陆相环境沉积建造、特殊环境沉积物等记录了响应的古地理、古环境变化与响应。陆地生物群分布、演化、更替与精确定年,脊椎-无脊椎生物(化石)埋葬特征,生物演化速率、消长关系和生物群(组合)更替的形式和性质,以及脊椎动物骨骼、牙齿的常量、微量元素、H-B-C-N-O-S和C-O-Sr等地球化学特征的研究可以恢复和重建古地理、古生态环境和古生态系统。  相似文献   

Evaluating ecosystem-based management options: Effects of trawling in Torres Strait,Australia     

Nick Ellis  Francis Pantus  Andrzej Welna  Alan Butler 《Continental Shelf Research》2008

A suite of management options for a prawn trawl fishery in Torres Strait, Australia was assessed for impacts on the benthic fauna using a dynamic management strategy evaluation approach. The specification of the management options was gained through consultation with stakeholders. Data for the model was drawn from several sources: the fleet data from fishery logbooks and satellite vessel monitoring systems, benthic depletion rates from trawl-down experiments, benthic recovery rates from post-experiment recovery monitoring studies, and benthic distribution from large-scale benthic surveys. Although there were large uncertainties in the resulting indicators, robust measures relevant to management were obtained by taking ratios relative to the status quo. The management control with the biggest effect was total effort; reducing trawl effort always led to increases in benthic faunal density of up to 10%. Spatial closures had a smaller benefit of up to 2%. The effect of closing a set of buffer zones around reefs to trawling was indistinguishable from the status quo option. Closing a larger area, however, was largely beneficial especially for sea cucumbers. When the spatial distributions of fauna prior to fishing were accounted for, fauna with distributions positively correlated with effort improved relative to those negatively correlated. The reduction in prawn catch under effort reduction scenarios could be ameliorated by introducing temporal closures over the full-moon period.  相似文献   

Aeschnidiid nymphs from the Jehol biota (latest Jurassic–Early Cretaceous), China, with a discussion of the family Aeschnidiidae (Insecta, Odonata)     

Junfeng Zhang 《Cretaceous Research》1999,20(6):813

Undoubted fossil nymphs of the family Aeschnidiidae within the Aeschnidioidea of the Anisoptera, Odonata are identified and described and their phylogenetic relationship and bioecological characteristics are deduced. The nymphs discovered previously in China, Mongolia and Russia and considered to be aeschnidiids are, in fact, unrelated to this group. All nine Chinese species in six genera can be merged into one alone, Aeschnidium heishankowense. It is the first animal from the ‘Jehol biota’ of East Asia to be linked with the species known from the Lower Tithonian of Germany. The geological age of the oldest strata bearing the fossil nymphs is debatable; it could be latest Jurassic rather than Early Cretaceous.  相似文献   

A Fresh Look at Dickinsonia： Removing It from Vendobionta     

ZHANG Xingliang Joachim REITNER 《《地质学报》英文版》2006,80(5):636-642

The Ediacaran Dickinsonia is well-known for being the only fossil to be assigned to many phyla, ranging from lichens, Cnidaria, Piatyheiminthes, Annelida, and a phylum of its own to a nonmetazoan kingdom. A new specimen from the Ediacaran fine-grained sandstone on the Winter Coast of the White Sea in northern Russia, which has an age of -555 million years ago, preserved convincing internal anatomies of definite animals, comparable with meridionai canals of extant ctenophores （comb jellies）. Additionally, we reconsidered Dickinsonia as a biradiaily symmetrical animal rather than a bilateral one as previously thought. The animal nature of Dickinsonia is, thus, well established and its affinities are most probably allied to ctenophores. This research is not only removing Dickinsonia from Vendobionta, but also bringing the fossil record of ctenophores forward to 20 million years before the Cambrian ＂explosion＂.  相似文献   

辽宁黑山恐龙化石的发现及其地层意义   总被引：3，自引：0，他引：3  

许坤  李瑜 《地层学杂志》1998,22(3):227-231

在辽宁省黑山县八道壕煤矿沙海组下部发现一颗恐龙牙齿化石,鉴定为Ａｓｉａｔｏｓａｕｒｕｓｓｐ．,时代属早白垩世,对我国北方热河生物群时代归属研究及侏罗系－白垩系界线的划分都具有重要意义。  相似文献   

A correlation between the Large Igneous Provinces and mass extinctions: constraint on the end-Guadalupian mass extinction and the Emeishan LIP in South China,eastern Tethys     

《International Geology Review》2012,54(10):1215-1233

ABSTRACT

Well-documented outcrops around the Emeishan Large Igneous Province (ELIP) in South China, eastern Tethys, encompassing the end-Guadalupian mass extinction have been investigated. Correlatable sections recording the event exhibit very similar lithological characters, positive-then-negative C isotope excursions and massive biotic demise. Detailed analyses of the fossil record and carbon isotopic variations were carried out on the Guadalupian–Wuchiapingian Boundary sections over the inner, middle, outer zones of the ELIP and its margin. Due to a pronounced decrease in marine habitat area and the environmental and ecological change over this part of the Tethys, the biota crisis records show the loss of numerous tropical invertebrate taxa, and exhibit fewer genera and smaller testing sizes and low productivity. The biota crisis was a sustainable and gradual reduction in diversity over the Capitanian. The associated carbon isotopic data reveal unusually high δ¹³C(carb) values before the late Capitanian, representing higher primary productivity (or buried rate) and more ¹³C-enriched CO₂ released by hydrothermal carbonate breakdown from the upper crust into the sediments at that time. Subsequently, an accelerated negative excursion across the boundary and the gradual excursion with low carbon isotope amplitude favours an increased influx of light ¹²C sourced by the volcanism around the eastern Tethys. The very similar time–space relation between the biota crisis and the Emeishan volcanism confirms that volcanic eruptions may have triggered the biota crisis event in South China. Intensive volcanism could result in detrimental environmental and ecological stresses, habitat loss, organic material splitting, or the emission of light carbon and thermal fluid (or aerosol), implying that the losses of the shallow-marine invertebrates either occurred geologically instantaneously or in a series of closely spaced crises coinciding with the initial phase of ELIP formation. These findings in South China may reveal the causal relation between mass extinctions and LIPs in a global context.  相似文献   

埃迪卡拉纪印痕化石是陡山沱期 宏体藻类的固着器吗？ ——Hiemalora与Gesinella的对比研究     

唐烽  金幸生  王约  丁明  赵元龙  高林志 《地质论评》2014,60(5):1009-1018

Hiemalora是一类广为分布的埃迪卡拉(Ediacaran)纪(震旦纪)圆盘状印痕化石,周围具流苏状或触须状突起,曾被解释为似水母动物,或某种叶状生物的固着器官,但以往罕见其与叶状生物体共同保存。本文报道了华南贵州震旦纪陡山沱组一类保存完好丰富的被确认为藻类的碳膜化石——革辛娜藻Gesinella,具有完整的须状固着构造。这一须状构造的形态和大小与Hiemalora非常相似,致密加厚的基部及其周围辐射状分布的丝状或须根状构造,可以分别和后者的中央盘以及周缘突起的"触须"相比较。陡山沱组的这一类碳膜化石同时保存有明显巨大的形同藻类的叶片和固着器,为研究埃迪卡拉生物群的底栖印痕化石提供了新的认识,即:盘状的Hiemalora可能是多细胞藻类的固着器官,而不一定是最初解释的似水母动物或其它叶状体生物的固着构造。不过,证实这一点尚需更进一步地研究埃迪卡拉纪生物的保存方式和埋藏环境。  相似文献