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1.
首次描述并研究了在湖南张家界四都坪乡四都坪剖面埃迪卡拉系陡山沱组下部硅质条带和结核中发现的保存精美的微体化石。化石组合包括大型具刺疑源类Cavaspina acuminata,Cavaspina basiconica,Gyalosphaeridium sp.,Mengeosphaera latibasis,Tanarium varium,Tanariumsp.和Urasphaera fungiformis;球状化石Megasphaera inornata;球状、丝状蓝藻化石Archaeophycus yunnanensis,Polytrichoides sp.,Salome hubeiensis,Siphonophycus robustum,S.typicum,S.kestron,和S.solidum以及多细胞藻类Wengania minuta。该微体化石组合与湖北峡东地区陡山沱组三段硅质结核中以大型具刺疑源类Tanarium为特征的组合面貌基本一致。这些微体化石的发现,进一步完善了我国埃迪卡拉系(震旦系)陡山沱组的生物地层序列,也为华南扬子地区陡山沱组的地层对比提供了新的古生物证据。  相似文献   

2.
保存于华南新元古代晚期陡山沱组中的磷酸盐化化石被认为与后生动物起源、真核生物演化有重要联系。位于鄂西黄陵隆起北缘的樟村坪地区,是华南最重要的工业磷矿产地之一,主要磷矿层属于埃迪卡拉纪地层,却鲜有磷块岩化石报道。此次研究利用钻孔样品的大量连续切片,在陡山沱组磷矿层中发现了丰富的保存精美的微体化石,化石组合包括可能的动物胚胎化石Megasphaera inornata;大型具刺疑源类Appendisphaerasp.,Cymatiosphaeroides kullingii,Dicrospinasphaera sp.,Ericiasphaera magna,Weissiella sp.;多细胞藻类Wengania globosa,W.exquisite,Sarcinophycus papilloformis,Thallophyca sp.,以及球状丝状蓝藻化石Archaeophycus yunnanensis,Cyanonema majus,Salome nunavutensis,Obruchevella minor,Siphonophycus kestron,S.typicum,S.robustum,S.septatum。这些微体化石的发现丰富了该区磷酸盐化化石资料,同时该化石组合面貌与黔中地区陡山沱组上磷块岩"瓮安生物群"以及峡东陡山沱组典型硅化生物群都具有相似性,化石层位的探讨也为华南不同沉积相区陡山沱组的地层对比提供了新的参考依据。  相似文献   

3.
埃迪卡拉纪(震旦纪)是早期多细胞生物起源与辐射的重要地质时期,磷酸盐化保存的微体化石则是研究该时期生命演化的重要窗口。目前对我国扬子地台埃迪卡拉系陡山沱组磷酸盐化微体化石的研究主要集中于贵州瓮安等地,其他地区的研究偏少。本次研究报道了保存于湖北保康白竹磷矿埃迪卡拉系陡山沱组磷块岩的微体化石。这些微体化石以三维磷酸盐化形式保存,种类丰富,共计14属21种,包括大型带刺疑源类Asterocapsoides sp.,Dicrospinasphaera sp.,Knollisphaeridium sp.,Mengeosphaera chadianensis,Tanarium conoideum,T.digi-tiforme,T.pilosiusculum,Tianzhushania sp.;球状化石Megasphaera inornata;球状蓝藻Archaeophycus yunnanensis,丝状蓝藻Cyanonema majus,Obruchevella minor,Salome sp.,Siphonophycus septatum,S.robustum,S.typicum,S.kestron;以及多细胞藻类Gremiphyca corymbiata,Thallophyca ramosa,Wengania exquisita,W.globosa。这些微体化石的发现,进一步丰富了白竹磷矿陡山沱组的化石组合,为华南扬子地台陡山沱组的生物地层对比提供了新的材料。  相似文献   

4.
Wengania globosa在陕西勉县茶店陡山沱组磷块岩中的发现   总被引:5,自引:2,他引:3  
本文报道陕西勉县茶店陡山沱组磷块岩中的疑源多细胞生物化石,其中Wenganiaglobosa属于首次报道。勉县茶陡山组磷块岩中的化石组合与贵州瓮安陡山沱组与可以直接对比,进一步了此两地的磷块岩属同期沉积产物。这一发现表明新元古代磷块岩中可能保存了多细胞生物早期演化中最精采的章节,因而进一步深入研究陡山沱组磷块岩大有必要。本文还讨论了疑在Meghystrichosphaeridium chadian  相似文献   

5.
本文描述的三叶脊类化石于2004年采自贵州东北部江口县桃映镇翁会村埃迪卡拉系陡山沱组上部庙河生物群,共2新属2新种:中国三射盘(新属新种)Triactindiscus sinensisgen.et sp.nov.及不规则似三角形盘(新属新种)Quasitriagondiscus irregularisgen.et sp.nov.。前者为大型盘状化石,具有3个呈碳质薄膜的长三角形叶脊,自盘体中央向边缘呈三辐射伸展,没有其它生物构造;后者为小型盘状化石,3条不规则叶脊在盘体中部形成似三角形并以此不同于其它三叶脊化石。庙河生物群2个三叶脊化石属相似于俄罗斯白海生物群的Albumares,Anfesta,Tribrachidium和澳大利亚埃迪卡拉生物群中的Tribrachidium,它们细节上有差异,但均属于埃迪卡拉系中三辐射对称的三叶动物。新的发现表明三叶动物在埃迪卡拉纪广泛分布于全球各地,也显示埃迪卡拉纪生物分异度比较高,辐射、两侧及三侧对称的动物均匀代表。贵州东北部江口桃映翁会庙河生物群含有丰富的宏观藻类及动物化石,如Protoconites,Cucullus,Sinospongia,Eoandromeda octobrachiata及新发现的2属三叶脊动物化石。江口庙河生物群组成上很相似峡东庙河生物群,也都位于陡山沱组上部黑色页岩中。江口庙河生物群不仅是整个庙河生物群的重要组成部分,也是埃迪卡拉纪生物演化的重要窗口。  相似文献   

6.
贵州埃迪卡拉纪瓮安生物群化石含量的统计分析   总被引:3,自引:0,他引:3  
贵州瓮安埃迪卡拉纪陡山沱组(635-551Ma)上磷矿段保存了大量精美的磷酸盐化微体球粒化石,它们主要由多细胞藻类、疑源类和处于不同发育阶段的多种动物胚胎化石组成,此外还包括少量后生动物的幼、成体化石。本文以贵州瓮福磷矿陡山沱组上磷矿段灰白色球粒状白云质磷块岩为研究对象,在总结瓮安生物群中不同生物化石的鉴别特征基础上,定量统计采自该层位的两组岩石样品(WA—I和WA-r1)的酸处理砂样中的所有化石。统计结果表明,瓮安陡山沱组该磷块岩中化石质量和岩石中磷酸盐组分质量成正线性相关,两个样品中化石占全部磷酸盐组分的质量百分比均在10%左右,其中多细胞藻类和疑源类化石占全部化石含量均少于10%。这一结果客观地反映了瓮安生物群的化石丰度,证实了保存在瓮安陡山沱组上磷矿段灰色富氧含磷埋藏相中的瓮安生物群主要由动物胚胎化石组成的特征。  相似文献   

7.
埃迪卡拉化石组成了全球埃迪卡拉纪地层中最具代表性的大型软躯体生物群落。根据其时代、化石种类以及岩性等,埃迪卡拉化石被划分为阿瓦隆、白海、纳玛三个不同组合。产自我国三峡地区埃迪卡拉纪晚期的石板滩生物群是为数不多保存在海相碳酸盐岩中的埃迪卡拉化石生物群。本文利用多元统计分析和网络分析等定量古生物方法划分出四个化石组合,检验并探讨了石板滩生物群所属的组合类型,以及初步探讨了石板滩生物群的生态空间利用情况。聚类分析和网络分析的结果,均倾向于将石板滩生物群划归于纳玛组合。然而在非度量性多维标度变换(NMDS)分析中,石板滩生物群因其化石属种组成的独特性和复杂性,离其他典型的纳玛组合化石产地的点位相距较远。石板滩生物群的生活方式以底栖固着和底栖移动类型为主,其独有的实体化石和丰富、复杂的遗迹化石属种,拓展了人们关于该时期生物对生态空间利用的认识。从生态空间利用的角度来看,石板滩生物群要远高于阿瓦隆组合,接近甚至略高于典型的纳玛组合和白海组合。  相似文献   

8.
在湖北宜昌秭归青林口剖面埃迪卡拉系陡山沱组二段燧石结核中发现大量微体化石,其中包括大型带刺疑源类8属9种(含1个未定种):Appendisphaera?hemisphaerica,A.magnifica,Dicrospinasphaera zhangii,Eotylotopalla dactylos,Mengeosphaera chadianensis,Taedigerasphaera lappacea,Tanariumsp.,Tianzhushania spinosa,以及Variomargosphaeridium lithoschum。同时在宜昌秭归金瓜墩剖面陡山沱组二段发现一些新的具刺疑源类化石材料,结合过去的报道,总结该剖面陡山沱组二段的疑源类化石组成:共7属9种(含3个未定种和1个相似种),及1个不定种,包括Appendisphaera magnifica,Appendisphaera sp.,Dicrospinasphaera zhangii,Knollisphaeridiumsp.,Mengeosphaera chadianensis,Mengeosphaera sp.indet.,Tianzhushania spinosa,Variomargosphaeridium lithoschum,Weissiella cf.brevis,以及Weissiella sp.。在宜昌三斗坪九龙湾剖面陡山沱组二段发现具刺疑源类Variomargosphaeridium lithoschum。这些化石材料丰富了对峡东地区陡山沱组二段具刺疑源类化石组成的认识,表明峡东地区陡山沱组具刺疑源类下组合与上组合在化石组成上的差别或许小于过去的认识。  相似文献   

9.
湖北保康陡山沱组磷酸盐化微体化石组合   总被引:4,自引:3,他引:1  
中国南方震旦系陡山沱组磷块岩、燧石和页岩中陆续发现的精美保存的化石生物群,为我们提供了一个栩栩如生的新元古代晚期生物演化的图景,表明多细胞真核生物在新元古代冰期之后发生了非常显著的分异。其中磷块岩化石库以生物细胞结构的完好保存而著称。继在贵州瓮安、陕西勉县茶店和江西上饶朝阳之后,湖北保康白竹磷矿陡山沱组磷块岩中也发现了类似的磷酸盐化化石生物群。保康化石组合中包括多细胞藻类Wengania,Paramecia和原地保存的Thallophyca;大型复杂疑源类Meghystrichosphaeridium,Echinosphaeridium和目前仅在保康发现的Bacatisphaera;球状蓝菌化石Archaeophycus,丝状蓝菌化石Siphonophycus和在陡山沱组磷块岩中首次发现的Obruchevella;同时,内部保存不同数量小球体的球状化石在保康也大量产出。古地理分析表明中国南方扬子地台陡山沱组磷块岩中保存的磷酸盐化化石库大都形成于浅水台地边缘地带。  相似文献   

10.
江西上饶朝阳磷矿新元古代晚期陡山沱组微体化石新材料   总被引:12,自引:0,他引:12  
江西上饶朝阳磷矿新元古代晚期微体化石产于上震旦统陡山沱组上部含磷地层中,微体化石组合包括疑源类Asterocapsoides sp.,Megasphaera inornata,Meghystrichosphaeridium chadianensis,M.gracilentum,丝状蓝绿藻Siphonophycus septatum,S.robustum,S.tpicum,S.kestron,S.soldium,Oscillatoriopsis sp.和Slome nunavutensis,及可能的多细胞藻类。该化石组合的发现为中国南方扬子区陡山沱组含磷岩系中微体化石生物群的研究提供新的材料。  相似文献   

11.
Diploblastic eumetazoans of the phylum Cnidaria originated during the Neoproterozoic Era, possibly during the Cryogenian Period. The oldest known fossil cnidarians occur in strata of Ediacaran age and consist of polypoid forms that were either nonbiomineralizing or weakly so. The oldest possible anthozoans, including the genus Ramitubus, may be related to tabulate corals and occur in the Doushantuo Lagerstätte (upper Doushantuo Formation, South China), the age of which is poorly constrained (approximately 585 Ma?). Conulariid scyphozoans may first appear as early as 635–577 Ma (Lantian Formation, South China). A definite conulariid, most similar to Palaeozoic species assigned to the genus Paraconularia, occurs in association with the possible scyphozoan, Corumbella werneri, in the latest Ediacaran (c. 543 Ma) Tamengo Formation of Brazil. Basal Cambrian (c. 540 Ma) phosphorites in the upper Kuanchuanpu Formation (South China) yield solitary polyps of the oldest probable anthozoan (Eolympia pediculata), which appears to have been a stem hexacorallian. This same formation contains fossils interpreted by some authors as pentaradial cubozoan polyps; however, both the oldest known cubozoans and the oldest hydrozoans, all medusae, may actually occur in the Cambrian (Series 3, c. 505 Ma) Marjum Formation (Utah, USA). Although these recently published palaeontological data tend to corroborate the hypothesis that Cnidaria has a relatively deep Neoproterozoic history, the timing of major internal branching events remains poorly constrained, with, for example, the results of some molecular clock analyses indicating that the two cnidarian subphyla (Anthozoaria and Medusozoa) may have originated as many as one billion years ago. Further progress towards elucidating the evolution and early fossil record of cnidarians may accrue from: (1) an intensive search for phosphatized soft parts in possible anthozoans from the Ediacaran Doushantuo Formation; (2) an expanded search for Ediacaran conulariids; and (3) additional detailed analyses of the taphonomy and preservation of Ediacaran and Cambrian cnidarians, including possible pentaradial cubozoan polyps from the Fortunian upper Kuanchuanpu Formation.  相似文献   

12.
埃迪卡拉纪是新元古代最后一个纪,是新元古代雪球地球事件与寒武纪生命大爆发之间地质历史最重要的转折时期,在研究地球早期生命演化方面具有举足轻重的地位。我国华南三峡地区埃迪卡拉系陡山沱组中下部的地层中,发现了大量的以具刺疑源类为主的微体化石,其中有两个形态简单、分布广泛的类型——分别是以光面、球状为特征的Leiosphaeridia和光面囊胞状、具开裂特征的Schizofusa。本文通过对这两种化石材料的细致观察与统计,对两者间的亲缘关系进行了详细探讨,认为Schizofusa开裂之前应为光面球体,即Schizofusa是某些光面球的发展演化后期阶段。  相似文献   

13.
《Palaeoworld》2022,31(1):1-13
Polybessurus, as a common element of the late Mesoproterozoic to early Neoproterozoic microfossil assemblages, has yet no confirmed record from post-Cryogenian strata. In this study, we report Polybessurus sp. from the Ediacaran Doushantuo Formation chert nodules in western Hubei Province, South China. Polybessurus specimens from the Doushantuo Formation are identical to their pre-Cryogenian counterparts in morphology (stacked concave lamellae), composition (organic matter), and preservational mode (silicification). The Doushantuo specimens generally have large tubes (average diameter ~157 μm, maximum diameter ~450 μm), and are often preserved separately and parallel to the bedding plane, whereas the pre-Cryogenian specimens have relatively small tubes (mostly thinner than 100 μm in diameter), and are often preserved gregariously and perpendicular to the bedding plane. Polybessurus may be formed by a variety of benthic micro-organisms, mainly cyanobacteria, e.g., stalk forming taxa like Cyanostylon and endolithic taxa like Solentia, that are capable of secreting EPS (extracellular polymeric substance) unidirectionally to push itself forward in the sediment. The producers of Polybessurus may have played a role in the benthic microbial community by making microburrows, affecting textures and microenvironments of inshore sediments. As the first unambiguous record of Polybessurus from Ediacaran strata, our new findings extend its distribution from the late Mesoproterozoic–early Neoproterozoic to the late Neoproterozoic.  相似文献   

14.
早寒武世和埃迪卡拉纪中的球状化石,一些已被归入可能的后生动物胚胎化石,由于具较为完好的三维保存方式以及近乎完美的胚胎发育序列,为早期后生动物的起源、分类、谱系演化及发育生物学提供了难得的实证材料。然而随着研究的深入,多数寒武纪胚胎的生物学分类位置未定;而数量异常巨大、又有独自的保存方式的晚元古代陡山沱组胚胎的真伪和生物学归属,更是争议未消。通过对现生生物胚胎的实验埋藏研究,可以揭示出各类生物胚胎在腐解、埋藏各阶段的保存潜力,而现代胚胎在各实验埋藏阶段形态、结构的变化,也能为化石胚胎的研究提供重要的实证材料。本文就是通过对虾卵胚胎各发育阶段腐解保存潜力的实验模拟研究,试图为球状化石的形成机制和化石归属提供一些实验室依据。  相似文献   

15.
The Ediacaran Doushantuo Formation in South China is underlain by the Cryogenian Nantuo Formation (glacial rocks) and overlain by the late Ediacaran Dengying Formation. It is characterized by well-preserved, large (normally >100 μm in size) spinose acritarchs (LSAs), which have been shown to be probably the only useful biostratigraphic tool for the global correlation of the early- and middle-Ediacaran. Acritarchs are organic microfossils normally known as single-celled eukaryotic organisms (protists). Although recent research suggests that some large spinose acritarchs may represent diapause egg cysts of metazoans, the biological affinities of the Ediacaran spinose acritarchs, especially for those displaying remarkable size ranges, are still debatable.Recently, smaller specimens of the Ediacaran spinose acritarchs have been found in cherts and phosphorites of the Doushantuo Formation in South China. Many described Ediacaran spinose acritarch taxa display large size variation (from tens to hundreds of microns in vesicle diameter), but some taxa only have smaller (<70 μm) specimens. The morphological comparison with Paleozoic counterparts indicates that some Ediacaran spinose acritarchs may have phylogenetic affinity to eukaryotic algae. More evidence, including wall ultra-structure, geochemical analysis and comparison with modern analogs, is needed to understand the biological affinity of the Ediacaran spinose acritarchs. The remarkable radiation of planktonic protists, characterized by abundant, diverse spinose acritarchs, occurred as early as in the late Neoproterozoic, i.e., 40–60 million years earlier than previously thought.  相似文献   

16.
Wang, Y & Wang, X. 2011: New observations on Cucullus Steiner from the Neoproterozoic Doushantuo Formation of Guizhou, South China. Lethaia, Vol. 44, pp. 275–286. The Neoproterozoic genus Cucullus is the most abundant and largest organism in the Miaohe biota in China, but has remained poorly understood both in morphology and classification. New material recently obtained from the upper Doushantuo Formation (Ediacaran) of northeastern Guizhou, South China, indicates that Cucullus bears thin organic walls composed of complex spongin fibres forming vertical filaments, which may have given rise to transverse filaments. Filaments, non‐mineralized spongin fibres, which may have served to support body, regularly interweave with each other in a body, and form openings on body sides that may have served as incurrent canals. The top pores may have served as excurrent canals. The overall features, including the organic wall, the complex spongin fibre networks, and the possible canal system of Cucullus, suggest a primitive element of the Demospongea. This benthic organism lived in a low‐energy, calm environment near or below the storm wave‐base with influence of episodic storms. Cucullus’ base nestled into the muddy substrate and its sacciform body floated in seawater. □ Cucullus, Doushantuo Formation, Neoproterozoic, Porifera, South China.  相似文献   

17.
峡东地区埃迪卡拉系陡山沱组疑源类生物地层序列   总被引:11,自引:0,他引:11  
峡东地区埃迪卡拉系陡山沱组自下而上可分4个岩性段:第1段为1.5-5m具帐篷和板裂构造的"盖帽白云岩";第2段是90-120m白云质灰岩夹黑色页岩,富含燧石结核;第3段为40-70m的白云岩夹燧石层和燧石结核;第4段10-20m为黑色碳质页岩夹碳酸盐岩透镜体.根据对该区九龙湾、王丰岗、田家园子、九曲脑、晓峰河、樟村坪等多条陡山沱组剖面的重新调查,确认第2和第3段分别含有不同的疑源类组合,二者被之间出现的δ13C负漂移(EN2)所分隔.下组合以Tianzhushania和高分异的具刺疑源类出现为特征.上组合与下组合的区别是:(1)Tianzhushania绝迹;(2)出现大量表面光滑,介于90-150μm的球状膜壳;(3)高分异的具刺疑源类既包括下伏上延的种类,又含有首次出现的新类型;(4)还出现可能为单细胞原生动物的微化石;(5)管状化石震旦圆圆茎(Sinocyclocylicus guizhouensis)首现.  相似文献   

18.
A fossil assemblage of diverse megascopic benthic algae is well preserved on bedding planes in black siliceous shales of the Neoproterozoic Lantian Formation (upper Sinian) at Lantian village, Xiunng county, Anhui Province, South China. Based on morphological differences, 12 taxa are recognized. Most specimens show both a holdfast and a vegetative thallus, some with dichotomous branching, which reveals that they are multicellular benthic algae. Each type presents a certain morphological appearance, e.g., spheroidal - Chuaria sp., filamentous - Doushantuophyton rigidulum , fan-like - Flabellophyton lantianensis. Four to six different benthic forms and more than 15 individuals are well preserved on the same bed with an area less than 150 cm2. These confirm that a great morphological evolutionary radiation of seaweeds took place no later than the Lantian epoch, with an absolute age around 570 Ma. Growth cycles in Flabellophyton strigata n.sp. reveal that periodical events, such as seasonal variations, occurred in that epoch. A benthic assemblage consisting of three differentiated macroscopic remains is similar to the Miaohe Biota reported from the Doushantuo Formation of the Yangtze Gorges 1200 km away, allowing biostratigraphic correlation of both of these Neoproterozoic Formations.  相似文献   

19.
产于贵州江口新元古界陡山沱组上部黑色碳质泥岩和硅质泥岩中的宏体生物群,多数为发育固着器的固着底栖生物。宏体藻类固着器的形态和保存方式可提供生物群生活环境和埋藏环境的信息。黔东北陡山沱期宏体生物群生活于相对平静、较为清澈的水体之中,固着基底为富含水份的粥性基底。可能与洋流有关的水流事件将宏体藻类折断或“连根”拔起;水流事件之后,沉积物将宏体藻类的遗体掩埋于还原性较强的环境之中,新生的和水流事件未致死亡的宏体生物在新的沉积物表面上继续生长。  相似文献   

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