Sophisticated particle-feeding in a large Early Cambrian crustacean

Most Cambrian arthropods employed simple feeding mechanisms requiring only low degrees of appendage differentiation. In contrast, post-Cambrian crustaceans exhibit a wide diversity of feeding specializations and possess a vast ecological repertoire. Crustaceans are evident in the Cambrian fossil record, but have hitherto been known exclusively from small individuals with limited appendage differentiation. Here we describe a sophisticated feeding apparatus from an Early Cambrian arthropod that had a body length of several centimetres. Details of the mouthparts resolve this taxon as a probable crown-group (pan)crustacean, while its feeding style, which allowed it to generate and handle fine food particles, significantly expands the known ecological capabilities of Cambrian arthropods. This Early Cambrian record predates the major expansions of large-bodied, particle-handling crustaceans by at least one hundred million years, emphasizing the importance of ecological context in driving adaptive radiations.     

Lower Cambrian yolk-pyramid embryos from Southern Shaanxi, China

TheCambrianexplosioniswidelyacceptedasthesuddenappearanceofnumerousbilateriananimalphylaatornearthebeginningofCambriantime[1,2 ] .The 5 30 million year oldMaotianshanShalefaunacontainstheoldestgoodwhole bodyfossilsofbilateri ans,documentinganincreasingnumberofpresent dayanimalphyla[3,4 ] orsubphyla[5] (evenincludingvertebrates[6～ 8] aswell)knownfromLowerCambri an .ThebeginningoftheCambrianperiodisdatedat5 43millionyearsago ,whenthefirstlargeandelabo ratefossilburrowstogetherwiththemicrosco…     

An Early Cambrian tunicate from China

Like the Burgess Shales of Canada, the Chengjiang Lagerst?tte from the Lower Cambrian of China is renowned for the detailed preservation as fossils of delicate, soft-bodied creatures, providing an insight into the Cambrian explosion. The fossils of possible hemichordate chordates and vertebrates have attracted particular attention. Tunicates, or urochordates, comprise the most basal chordate clade, and details of their evolution could be important in understanding the sequence of character acquisition that led to the emergence of chordates and vertebrates. However, definitive fossils of tunicates from the Cambrian are scarce or debatable. Here we report a probable tunicate Cheungkongella ancestralis from the Chengjiang fauna. It resembles the extant ascidian tunicate genus Styela whose morphology could be useful in understanding the origin of the vertebrates.     

Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence

Phosphatized and three-dimensionally preserved embryos and spherical fossils of metazoan recovered from the Kuanchuanpu Member, Dengying Formation in southern Shaanxi, China provide nice devel- opmental sequence for the studies of origination, taxonomy, phylogenic evolution and developmental biology of early animals. Ontogeny of these larva fossils has not been systemically studied mainly due to their poor preservation and limited identification. The Kuanchuanpu Member, predominated by phosphorites and cherts, yields phosphatized animal embryos, particularly those of Olivooides and Punctatus which have high resolution in fine structures and different ontogeny developmental stages. An ontogenetic sequence of the Punctatus is established mainly base on its developmental transitions from body part to oral one, which is perfectly consistent with the embryonic ontogeny sequence pro- posed by Bengtson and Yue (1997). Furthermore, a new genus Quadrapyrgites gen. nov is erected to receive a larva with tetraradial body plan.     

贵州台江下寒武统Bathynotus(宽背虫)一新种

本文扼要介绍了Bathynotus的分类位置、研究动态及研究意义,并详细描述了该属的一个新种。     

澄江化石库中川滇虫属化石的新信息

目的 对澄江化石库中数量可观的软躯体化石卵形川滇虫(Chuandianella ovata)的形态以及生态进行研究。方法 运用解剖学、形态比较学方法。结果 扩展性描述了该属种动物身体的内部构造;对该属种壳表装饰、尾扇结构等形态描述进行了修正;首次得出卵形川滇虫不属于瓦普塔虾科(Waptiidae)的结论;结合形态、功能及生态之间的联系引出了卵形川滇虫生活的方式及古环境。结论 川滇虫是一种生活于浅海底部的自由游泳者,以植物或浮游生物为食,在进化程度上稍低于瓦普塔虾。     

Eocrinoid echinoderms from the Lower Cambrian Guanshan Fauna in Wuding, Yunnan, China

This is a brief report of a new occurrence of eocrinoids from the Early Cambrian Wulongqing Formation in Yunnan, China. The eocrinoids from the Guanshan fauna are among the earliest known eocrinoids. Different from many other Early and Middle Cambrian eocrinoids, the Guanshan eocrinoids are char-acterized by the absence of sutural pores and epispires, the long and spiral brachioles, the extremely long stalk, and the ratio of the length of the stalk versus that of the calyx. The discovery of the eocri-noids from the Guanshan fauna not only provides new information to the investigation of the early evolution of this animal group, but also shed new light on the occurrence and migration of early eocrinoids.     

An armoured Cambrian lobopodian from China with arthropod-like appendages

Cambrian fossil Lagerst?tten preserving soft-bodied organisms have contributed much towards our understanding of metazoan origins. Lobopodians are a particularly interesting group that diversified and flourished in the Cambrian seas. Resembling 'worms with legs', they have long attracted much attention in that they may have given rise to both Onychophora (velvet worms) and Tardigrada (water bears), as well as to arthropods in general. Here we describe Diania cactiformis gen. et sp. nov. as an 'armoured' lobopodian from the Chengjiang fossil Lagerst?tte (Cambrian Stage 3), Yunnan, southwestern China. Although sharing features with other typical lobopodians, it is remarkable for possessing robust and probably sclerotized appendages, with what appear to be articulated elements. In terms of limb morphology it is therefore closer to the arthropod condition, to our knowledge, than any lobopodian recorded until now. Phylogenetic analysis recovers it in a derived position, close to Arthropoda; thus, it seems to belong to a grade of organization close to the point of becoming a true arthropod. Further, D. cactiformis could imply that arthropodization (sclerotization of the limbs) preceded arthrodization (sclerotization of the body). Comparing our fossils with other lobopodian appendage morphologies--see Kerygmachela, Jianshanopodia and Megadictyon--reinforces the hypothesis that the group as a whole is paraphyletic, with different taxa expressing different grades of arthropodization.     

巨鲕成因探讨:来自上扬子地区下寒武统、中泥盆统及下三叠统的证据

通过对下寒武统、下三叠统与中泥盆统金宝石组葛万藻成因的核形石对比研究认为,微生物是巨鲕形成的主要因素之一。微生物参与构建巨鲕暗色纹层,促进同心纹层加积,对巨鲕的形成具有建设性作用。在金宝石组核形石纹层中微生物发育的区域,纹层厚度不均匀且形态不规则,说明微生物对巨鲕规律纹层是具有破坏性的。巨鲕和核形石都是在无机化学和微生物共同作用下形成的产物,不同的水体环境制约着微生物的发育程度,进而控制了巨鲕与核形石的形成。     

Trace element geochemistry of the Lower Cambrian black rock series from northwestern Hunan, South China

Samples of black rock series collected from the Lower Cambrian Niutitang Formation, northwestern Hunan Province, China, were analyzed for trace elements.The trace element geochemical characteristics of the ore layer (high enrichments of Ni, Mo, V, U, Cu, Pb, Zn, Cd, Tl and Ba; high U/Th ratios and LREE-enriched patterns with positive Eu and Y anomalies) support the assumption that the Ni-Mo polymetallic layer is of submarine hydrothermal origin.High field strength elements (HFSE) and lithophile elements such as Nb, Ta, Zr, Hf, Li, Be, Rb, Cs, Th and Sc are remarkably higher in the upper unit than those in the lower unit of the Niutitang Formation.These features may reflect that hydrothermal contributions were diminished, and terrigenous constituents were increased in the sediments of the upper unit of the Niutitang Formation.     

Lower Cambrian small shelly faunas from Zhejiang (China)and their biostratigraphical implications

Despite a long history of research on the Early Cambrian in China most available data on small skeletal fossils concern fossil associations of the shallow carbonate platform. Information on skeletal fossils from marginal shelf environments of the Yangtze Platform is scanty, which may reflect the rarity of fossils in deeper sedimentary environments but is also due to limitation of carbonate distribution and outcrops, difficulties in fossil extraction, and a general research focus on the Precambrian-Cambrian boundary beds on the carbonate platform. Here we present a documentation of Meishucunian to Qiongzhusian small skeletal fossils from the lower Hetang Formation and the chert unit at its base from the Jiangshan region, Zhejiang Province, representing a relatively deep shelf environment compared to the inner shelf region. The earliest association (Meishucunian) from the chert unit underlying the Hetang Formation is mainly characterized by the occurrence of Protohertzina anabarica, P. unguliformis, Fengzuella zhejiangensis, and Kaiyangites novilis, which differs somewhat in composition from SSF-associations of typical inner shelf deposits. The enigmatic skeletal fossil Fengzuella zhejiangensis, which exhibits an unusual secretional growth mode previously unrecognized from the Early Cambrian, is described in detail. A younger (Qiongzhusian) fossil association contains numerous arthropod remains, such as disarticulated spines of arthropods (Jiangshanodus- and Kijacus-type), which have previously been considered as conodont-like fossils, and bradoriid valves.     

下扬子皖南地区下寒武统大陈岭组页岩特征及其沉积环境

下扬子皖南地区下寒武统大陈岭组发育富有机质页岩,前期对该套页岩的关注和研究较为薄弱。为探索大陈岭组页岩特征及其沉积环境,以该区页岩气探井WY1井为研究对象,基于岩心、测井资料,通过全岩X射线衍射、氩离子抛光扫描电镜、有机地球化学、元素地球化学等测试手段,重点分析页岩岩石矿物组成特征、有机地球化学特征、孔隙特征,讨论其沉积环境。结果表明：大陈岭组页岩矿物组成以石英、黏土矿物为主,为生物成因硅质页岩,过量硅含量为33.77%～61.79%,占总硅质含量的46%～75%;页岩有机质丰度高,TOC分布在2.27%～7.42%之间,平均值为4.06%,等效镜质体反射率（Ro,eqv）为3.37％～5.53％,均处于过成熟演化阶段,有机质严重碳化,测井电阻率普遍低于1 ?·m;发育无机孔隙、有机质孔隙和微裂缝3种孔隙空间类型,有机质孔隙较发育,但主要为孔径10～20 nm的小孔,有效孔隙度平均为1.25%;大陈岭组形成于深海至滞流浅海,自下而上水体滞留程度增强,整体处于贫氧—厌氧的古水体环境,沉积期气候温暖湿润,古生物繁盛,古生产力较高,生物Ba含量为1 738.15～5 687.74 ug/g,平均值为3 309.63 ug/g,沉积环境有利于有机质的富集保存;皖南地区大陈岭组富有机质页岩发育,具备页岩气形成的基本条件,深化过热演化程度页岩气富集主控因素研究,评价优选保存条件较好的稳定区,有望实现勘探新突破。     

Skeletal faunas from the Qiongzhusian of southern Shaanxi: biodiversity and lithofacies-biofacies links in the Lower Cambrian carbonate settings

The Xiaoyang section, located in Zhenba County of Shaanxi Province, is important both for documenting the biodiversity of the Qiongzhusian Stage (Lower Cambrian) and for analyzing lithofacies-biofacies links in carbonate depositing environments on the Yangtze Platform.The skeletal fossils from the Xihaoping Member, including linguloid valves, cambroclavid and chancelloriid sclerites, genal and occipital spines of polymerid trilobites, and tubular fossils, are described here as the Eoobolus-Cambroclavus fauna, which mainly occurred in peritidal environments.The fossils from the argillaceous limestones of the lower Shuijingtuo Formation, containing lingulate brachiopods, eodiscoid trilobites, bivalved arthropods, microdictyoniid sclerites and siliceous sponge spicules, are regarded as the Palaeobolus-Hupeidiscus-Kunmingella fauna, which presumably lived in subtidal or deeper water environments.The faunal diversity in the Xihaoping Member is lower than that in the lower Shuijingtuo Formation.The investigations of the skeletal fossil assemblages from carbonate lithofacies in southern Shaanxi will significantly contribute to a detailed documentation of the biodiversity during the Qiongzhusian interval on the Yangtze Platform and add new knowledge on the Cambrian bioradiation.     

Pb-Pb isotope dating of black shales from the Lower Cambrian Niutitang Formation, Guizhou Province, South China

Withthedevelopmentofnewanalyticaltech niquesandstate of artinstruments ,isotopetracinganddatingmethodshavemadeconsiderableprogressinrecentyears .Inparticular ,variouskindsofradio genicisotopedatingmethodshavebeenappliedsuc cessfullyinigneousrocks.However,directdatingofsedimentaryrocksremainsundevelopedandcontro versial.Inmostcases ,researchersapplyU PbandK ArorAr Armethodstodatingvolcanicashesthatareinterbeddedwithinsedimentarystratainanattempttoobtaintheageofsedimentsindirectly[1] .Howev e…     

黔南下寒武统喳拉沟组黑色岩层风化特征

黑色岩层是一种广泛分布且具有特殊性质的岩石,探讨黑色岩层的风化特征,为黑色岩层边坡治理提供理论依据。选取黔南三都地区下寒武统喳拉沟组黑色岩层为研究对象,利用浸泡试验、水质分析试验模拟黑色岩层的水岩化学作用过程,通过黑色岩层风化中的矿物特征、化学成分特征来确定其风化阶段。研究结果表明:研究区黑色岩层在水岩作用中涉及多个复杂的化学过程,通过溶解、水解、水合作用逐步形成稳定的黏土矿物及次生矿物;黑色岩层的化学风化已完成去Na、Ca阶段,并初步进入中期的去K风化阶段。     

贵州遵义下寒武统牛蹄塘组生物群中的海绵化石

遵义松林中南村下寒武统牛蹄塘组中下部,特别是下部黑色泥岩中产有大量的海绵骨针,形态多样,初步研究有多达10属以上的海绵动物,与澄江生物群的海绵相比,牛蹄塘组的海绵动物化石其组合特征以六射海绵动物为主,它的发现增添了寒武纪生物组成的信息,为海绵动物从晚新元古代的发生以至穿越寒武纪的演化过程及寒武纪生物大爆发的定性,量度提供了重要信息及资料,描述了4属2个种。1个相似种和1个未定种。Hyalosinica sp.;Saetaspongia densa Mehl et Reitner,1993;Leptomitus teretiusculus CHen,Hou et Lu.1989;Crumillospongia cf.biporosa Righy,1986,它们分属于海绵动物的六射海绵纲和普通海绵纲。     

苏北地区下寒武统幕府山组页岩气勘探前景

通过野外地质调查、岩心观察、老井复查、分析测试及模拟实验等方法,研究苏北地区下寒武统幕府山组富有机质泥页岩的有机地球化学特征、储层特征及含气性等,并探讨其页岩气勘探前景.幕府山组富有机质泥页岩发育于该组下部,为陆棚-盆地相沉积,厚度一般在50～200m之间,顶界埋深一般为2.5～4.0 km,干酪根类型主要为Ⅰ型和Ⅱ1型;有机质丰度高,TOC平均值为3.32％,最高可达12.1％.有机质热演化程度普遍较高,等效镜质体反射率为0.73％～3.01％,平均为2.83％,多处于高成熟—过成熟阶段.矿物成分以黏土和石英为主,含有少量钾长石、石膏等,黏土矿物主要成分为伊利石和伊/蒙混层,不合蒙脱石.泥页     

Phosphatized embryo fossils from the Cambrian explosion

The earliest Cambrian (Meishucunian) phosphatized metazoanOlivooides from the Yangtze platform is represented by dierent developmental stages: from blastula through possible gastrula to tissue differentiation and finally to the hatched animals. The fossilization of embryos opens a new field in palaeontologypalaeoembryology. Embryological studies will be of importance for the understanding of ontogeny and phylogeny of metazoans from the Cambrian explosion.     

川西南地区下寒武统龙王庙组储层特征

综合钻井、测井及地震资料分析,进一步明确川西南地区下寒武统龙王庙期发育两期局限台地鲕粒、砂屑浅滩,平面上以资阳—磨溪地区为浅滩发育的中心,向四周减薄,纵向上由中心区稳定的早、晚两期浅滩迁移演变为边缘的晚期滩。储层岩性为溶孔微晶-细晶白云岩、滩相砂屑白云岩、鲕粒白云岩,储集空间以粒间溶孔、粒内溶孔、晶间溶孔为主,资阳—磨溪地区为中低孔渗—高孔渗,测井表现为低伽马、低电阻、低密度、较高的声波时差,为孔隙型储层;白云石化是形成储层的基本条件,溶蚀作用对优质储层发育起决定性作用。资阳—磨溪地区储层厚度为30~50m,孔隙度为4%~6%,发育最好;向南西、南方向储层厚度变为10~30m,孔隙度为3%~4%,因此,资阳-磨溪地区是龙王庙组油气勘探的最有利区。     

江西修武盆地下寒武统黑色页岩矿物成分特征及意义

以江西修武盆地下寒武统王音铺组、观音堂组黑色页岩为研究对象,通过对野外剖面样品和钻井取心样品定性和定量分析,研究修武盆地下寒武统页岩气储层矿物成分特征,结果表明,王音铺组、观音堂组黑色页岩矿物成分以黏土矿物和石英为主,石英的平均质量分数为58.63%,黏土矿物平均为25.4%。其次为方解石,平均为51.46%,另外还含有较高的长石和黄铁矿,平均质量分数分别为2.5%和4.68%。其余矿物如方解石、白云石、(硬)石膏等含量较少,平均质量分数5%。这种矿物成分组成与Barnett页岩及龙马溪组页岩既有相似性,又有差异性。修武盆地下寒武统页岩矿物组分所反映的沉积环境、有机质演化及黑色页岩储集意义表明,该套页岩石英的质量分数50%的泥(页)岩厚度接近50m,是理想的页岩气勘探开发层位。