Kaili Biota: A Taphonomic Window on Diversification of Metazoans from the Basal Middle Cambrian: Guizhou, China

1 Introduction The Burgess Shale Biota was discovered in the Cambrian strata of western Canada by American paleontologist C. D. Walcott in 1909 (Walcott, 1911). The fauna contains more than 140 metazoan genera (Robison, 1991, Briggs et al., 1994), with a preservational range from hard skeletal parts, non-mineralized remains and internal soft-tissue and soft-body remains. Following that discovery up to 40 similar taphonomic locations have been found globally in Lower and Middle Cambrian …     

Cambrian Burgess Shale-type Lagerstätten in South China: Distribution and significance

The final assembly of the supercontinent Gondwana during the Pan-African orogenic episodes (ca. 550–520 Ma) almost simultaneously took place with the Cambrian explosion that is best manifested by a number of Cambrian Burgess Shale-type Lagerstätten in South China. The relationship between South China and Gondwana during the Cambrian is far from consensus. Burgess Shale-type Lagerstätten may have potential importance for the paleogeographic reconstruction. However, such Lagerstätten have been known in large number only in Laurentia and South China, far less common in Gondwana and other continents. Burgess Shale-type Lagerstätten in South China are not evenly spaced through the Cambrian. They appear to be concentrated in the Lower Cambrian, particularly in the Canglangpuian and Qiongzhusian stages, much reduced in number from the uppermost Lower Cambrian. Of ten reported such Lagerstätten, only the Kaili biota (basal Middle Cambrian) is known to be younger than Early Cambrian. This reduction could be explained by the fact that vast areas of siliciclastic facies in both the western plate interior (platform) and the eastern slope basin during most time of Early Cambrian (Meishucunian to Canglangpuian) is evolved into carbonate facies at the very end of Early Cambrian (Longwangmiaoian). It has been known from this study that both siliciclastic platform facies and slope basin facies (shale basin) could preserve soft-bodied fossils. Cambrian Burgess Shale-type Lagerstätten in South China are of great significance for providing a sequences of exceptionally preserved biota in a chronological succession. Comparison of such Lagerstätten in a chronological framework may give us more details on the Cambrian explosion events.     

贵州台江早—中寒武世凯里组的宏观藻类化石

本文描述了贵州寒武纪凯里组中的宏观藻类化石７属１２种,其中有６个新属１０个新种;Ｂｏｓｗｏｒｔｈｉａ ｓｉｍｕｌａｎｓ,Ｂ．ｇｙｇｅｓ,Ｅｏｌａｍｉｎａｒｉａ ｇｒａｎｄｉｓ ｇｅｎ。ｅｔ ｓｐ．ｎｏｖ。,Ｅ．ｐｅｒｅｌｅｇａｎｓ ｇｅｎ。ｅｔ ｓｐ。ｎｏｖ．,Ｆ．ｖｅｉｎ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．,Ｋａｉｌｉｐｈｙｔｏｎ ｓｉｍｕｌａｎｓ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．,Ｐａｌａｅｏｓｐｉｎｅ     

First report on Guanshan Biota(Cambrian Stage 4) at the stratotype area of Wulongqing Formation in Malong County,Eastern Yunnan,China

Exceptionally preserved fossils,such as those from Cambrian Burgess Shale-type fossil-Lagerstatten are critical because of their unique contributions to knowledge of the phylogenetic radiation and palaeoecological expansion of metazoans during the Cambrian explosion.Critically,these deposits provide information that is usually unobtainable from shelly and skeletonized fossils alone.The Guanshan Biota(Cambrian Series 2,Stage 4)in the Yunnan Province of South China,has produced abundant and diverse,exquisitely preserved fossils that often retain soft tissues and organs.To date,most fossils from the Guanshan Biota have been collected from localities such as Gaoloufang and Gangtoucun,which have become inaccessible due to new urban expansions and constructions of residential buildings.Here we present the first report of soft bodied fossils from a new section at Kanfuqing,close to the Wulongqing village in Malong County,approximately 3 km east of the Wulongqing Formation stratotype section.Fossils retain soft morphology,and include brachiopods with delicate marginal setae,priapulids with well-preserved sclerites and vetulicolians with entire sections of body.In addition,this fauna includes rare occurrences of trilobites preserved with soft tissues replicated as pyrite pseudomorphs after weathering.This discovery represents an important palaeogeographical extension of soft-bodied fossils of the Guanshan fauna to the east of the Xiaojiang Fault(related to Tsinning tectonic movements ca.700 Ma).The fauna from the new Kanfuqing section is similar to that reported from the Wulongqing Formation west of the Xiaojiang Fault,and thus has significant implications for early Cambrian palaeogeography,faunal successions and palaeoenvironments of eastern Yunnan.     

全球早、中寒武世藻类生物地理分区初探

澄江生物群、凯里生物群、加拿大布尔吉斯生物群和西伯利亚藻群中均有丰富的藻类化石。根据前寒武纪宏观藻类的分布以及凯里生物群和布尔吉斯页岩生物群中藻类和后生动物的相似性，讨论了前寒武纪至中寒武世期间生物地理分区的控制因素。对几个生物群中的藻类化石和后生动物化石的对比研究发现,在相近的纬度范围内, 动植物化石组合特征非常相似; 而纬度明显差异时, 藻类生物群及后生动物群也具有明显的差异。由于后生生物在前寒武纪至中寒武世期间具有低的演化程度和分异能力，因此生物地理分布的主要控制因素是古纬度。而Schopf (1976)的生物地理分区模式不适合这一时期的生物地理分区。结合前寒武纪至中寒武世后生生物化石的分布情况，建立了前寒武纪-中寒武世时期的生物地理分区模式。这个模式较好地解释了分布在北美大陆和华南大陆上的寒武纪生物群相似的原因。     

贵州台江中寒武世凯里组中分枝状宏观藻类化石

本文描述了贵州中寒武世凯里组中的分枝状宏观藻类化石5属7种，即：Marpolia spissa Walcott,Marpolia aequalis Walcott,Guizhouella ramulosa Yang(gen.et sp.nov.),Doushantuophyton lineare Chen,Thamnophton formosus Yang(gen.et sp.nov.),Eoulothrix fibrillata Ding,Eoulothrix flabellophyton Yang(sp.mov.)。根据大量的藻类与凯里生物群共生特征，从藻类的生态及生物群分布受到沉积韵律控制等特征分析，认为凯里生物群生活环境的水深应该在30－60m，而埋藏和保存环境的水深是150m左右。另外，将凯里生物群中的宏观藻类化石与震旦纪陡山沱期的藻类化石进行了比较，两者在以分枝状藻类占主要组成上是相似的，从这一方面来说，晚震旦世宏观藻类与寒武纪宏观藻类没有大的演变，但寒武纪宏观藻类以出现钙质珊瑚藻类、分枝更加复杂的类型和具有锯齿状叶状体、生殖托构造的藻类为特征。     

寒武纪生命扩张及澄江动物群的意义

生命在地球上的出现及其演化有较长的历史。地球的物理、化学条件是早期生命出现的外因。早寒武世西南地区地质、气候及富含营养的浅海水域是澄江动物群在后生动物演化的关键时期出现的外因。“寒武纪生物的扩张”应有恰当的翻译，同时对现代生物学的“适应辐射”应有清楚的中文解释。从新近发现看，早、中寒武世的澄江动物群及布吉斯页岩动物群与埃迪卡拉动物群具有一些联系，埃迪卡拉动物群并没有在寒武纪时完全绝灭。     

祁连和秦岭地区寒武纪和奥陶纪古生物区系关系的探讨

我国西北地区由不同地体组成,构造运动复杂。由于缺乏充分的古生物学证据,古生物区系的识别和归属一直是有待解决的问题。本文在前人工作的基础上,依据各类动物群特征的分析,较详细地探讨了我国祁连和秦岭地区相关地层区中-晚寒武世和奥陶纪动物群的性质及其古生物类型的归属,确定了过渡型动物群在祁连和秦岭地区的大体分布范围。同时,结合地球动力学和古地理学研究成果的分析,探讨了导致在祁连和秦岭地区中-晚寒武世和奥陶纪时存在着与华南相似过渡类型动物群的两种可能原因。一种可能是中-晚寒武世和奥陶纪时塔里木板块位于扬子板块西边,中朝板块位于扬子板块之北,祁连和秦岭可能位于扬子和塔里木板块之间,存在与华南及华北动物群交流的基本条件,产生了大体相近的动物群。另一种可能是中-晚寒武世和奥陶纪时祁连和秦岭地区存在一些原位于扬子板块北部边缘的地体,在这些沿扬子板块北缘分布的地体上发育了与南部边缘相似的生物群或生物类型。中生代之前,沿扬子板块主体和北部边缘地体之间的走滑活动,可能使扬子板块主体向东移动了几百公里,而其边缘那些属于祁连和秦岭的地体向东移动的幅度不大,从而造成现今祁连和秦岭地区存在与扬子板块东南部地区大体相似的具过渡性质的生物群或生物类型,而扬子板块北部边缘又缺少边缘过渡相带的现状。     

The Allochthony of the Argentine Precordillera Ten Years Later (1993–2003): A New Paleobiogeographic Test of the Microcontinental Model

Recent and new faunal data from the Cambrian to Silurian rocks of the Precordillera, Famatina and Northwest Argentina basins are used to discriminate between different paleogeographic models, and especially to establish to what extent they are compatible with a previous conclusion that the Precordillera is a Laurentian-derived microcontinent. There is no paleontological evidence to support a para-autochthonous Gondwanan origin of the Precordillera. The strong differences in the Cambrian trilobite faunas and lithologic successions preclude a common origin of the Precordillera terrane, eastern Antarctica and South Africa. Recent discoveries of brachiopods and organisms of the Phylum Agmata strengthened Laurentian affinities during the Cambrian. The latest Cambrian-early Ordovician faunas that inhabited the autochthonous Northwest Argentina basin, including the western Puna volcaniclastic successions, are mostly peri-Gondwanan. The early Ordovician brachiopods, ostracods and trilobites display mixed Laurentian, Baltic and Avalonian biogeographical links supporting a drifting of the Precordillera across the Iapetus Ocean. Increasing Gondwanan elements during the Llanvirn, along with varied geological evidence, indicate that the first stages of collision may have begun at that time, involving a major change in the plate kinematics. The distribution of facies and faunas, basin development, and timing of deformation are interpreted as resulting from a north to south diachronous closing of the remnant basin during the last phases of convergence and oblique collision of the Precordillera terrane with the Gondwana margin. The high level of endemism of Caradoc faunas may be a consequence of the rearrangement and partial isolation of sedimentary areas during the strike-slip movement of the colliding Precordillera plate with respect to the Gondwana margin. Suggested relationships between facies distribution, geographic barriers and faunal migrations before and during the collision are depicted in a series of schematic reconstructions at five time slices from late Cambrian to Silurian.     

Biomarker and isotopic signatures of an early Cambrian Lagerstätte in the Stansbury Basin, South Australia

The lower Cambrian (Series 2) Emu Bay Shale biota, found at Big Gully on the north coast of Kangaroo Island, South Australia, is by far the richest Burgess Shale-type (BST) fauna in the southern hemisphere. While the trace element geochemistry of the host shale shows it accumulated beneath an oxic water column, this appears difficult to reconcile with the exceptional preservation of organs such as gut glands, muscles and eyes in some of its fauna. Micro-scale sealed vessel (MSSV) pyrolysis of kerogen isolated from a solvent extracted sample of fossiliferous Emu Bay Shale provided independent confirmation of its redox status and also implicated cyanobacteria in the preservation of its fauna. Thermal extraction and pyrolysis each yielded alkanes displaying a low ratio of pristane to phytane (pr/ph = 1) and n-alkanes with a marked odd/even predominance in the <C₂₀ range. The latter molecular signature is diagnostic of Gloeocapsomorpha prisca and is the first indication that mats of this or a similar coccoid cyanobacterium were involved in the taphonomy of a BST deposit. Hopanes (including 2-methylhopanes) are far more abundant than steranes and the shale’s bulk organic matter has δ¹³C values in the range −32‰ to −28‰, providing further evidence of the cyanobacterial affinity of its microbial biomass. Thus mat-forming cyanophytes, rather than sulfur-oxidising bacteria, may have played a key role in maintaining a sharp redox boundary at the sediment-water interface during deposition of the Emu Bay Shale Lagerstätte, thereby enabling the survival of soft body parts within its fossil fauna for long enough to permit inorganic replication of their fine detail during late diagenesis.     

河南灵宝朱阳下寒武统辛集组软体动物群的发现

河南灵宝朱阳地区下寒武统辛集组中新发现的小壳动物化石包括软体动物群的软舌螺、单板类、双壳类和腹足类以及海绵骨针和齿形类。该动物群可与安徽淮南雨台山组、河南确山、叶县、宝丰及陕西洛南辛集组动物群对比，时代属早寒武世中期，与澳大利亚新南威尔士早寒武世中期软体动物群属同一生物地理区。软体动物有可能在中国云南开始出现，并迅速迁移至扬子浅海各地，后经某种渠道迁移到华北地台南缘，演化成新的动物群。     

Faunal dating of the late Cenozoic of southern Africa,with special reference to the Carnivora

Since chronometric data comparable to that available from the late Cenozoic succession of East Africa have not, and probably cannot be obtained in southern Africa, faunal dating methods retain their traditional significance in the latter area. Five successive late Cenozoic mammal ages, the Namibian, Langebaanian, Makapanian, Cornelian, and Florisian have been proposed as a framework for discussions relating to the chronology of southern African mammalian faunas. The Namibian fauna is poorly known, but is evidently of Miocene age. It is not discussed in this paper. The Langebaanian fauna is well known only from the prolific occurrence at the type site of Langebaanweg and is Pliocene in age. Makapanian faunas are best represented at the Transvaal Australopithecine sites and probably overlap the Plio-Pleistocene boundary. The Cornelian fauna is not as well known as others, the largest assemblage having been recorded from Elandsfontein, although this assemblage is one which is unfortunately temporally heterogeneous. Florisian faunas have been recovered from a relatively large number of localities, including several for which there are radiometric dates. The recorded southern African fossil Carnivora are listed and the local evolution of this group is discussed in terms of the mammal age chronology. It is concluded that secure faunal dating of individual fossil occurrences is enhanced by an appreciation of the nature of changes undergone in evolutionary lineages, while an uncritical knowledge of recoreded taxa is less useful.     

扬子地台前寒武纪－寒武纪界线地层的微体植物化石群

前寒武纪一寒武纪界线地层在扬子地台发育良好、分布广泛,并有包括微体植物群、海藻、瓶形原生物、具硬体动物及‘澄江动物群’等化石的发现。因而,扬子地台成为研究前寒武纪－寒武纪界线生物地层的代表地区之一。基于对扬子地台前寒武纪－寒武纪界线地层已知微体植物化石记录的回顾和论定,总结概括了下寒武统微体植物化石组合：寒武系最底部硅质磷块岩中的Ｍｉｃｒｈｙｓｔｒｉｄｉｕｍ－Ｐａｒａｃｙｍａｔｉｏｓｐｈａｅｒａ－Ｍｅｇａｔｈｒｉｘ组合和较高层位页岩的Ｓｋｉａｇｉａ－Ａｎｎｕｌｕｍ－Ａｒｃｈａｅｏｄｉｓｃｉｎａ组合。它们分别与Ａｎａｂａｒｉｔｅｓ－Ｃｉｒｃｏｔｈｅｃａ－Ｐｒｏｔｏｈｅｒｔｚｉｎａ小壳动物化石带和Ｐａｒａｂａｄｉｅｌｌａ及Ｅｏｒｅｄｌｉｃｈｉａ三叶虫带相对应。与东欧地台疑源类生物地层相对照,扬子地台Ｍｉｃｒｈｙｓｔｒｉｄｉｕｍ－Ｐａｒａｃｙｍａｔｉｏｓｐｈａｅｒａ－Ｍｅｇａｔｈｒｉｘ组合的纵向分布大体和东欧地台Ａｓｔｅｒｉｄｉｕｍｔｏｒｎａｔｕｍ－Ｃｏｍａｓｐｈａｅｒｉｄｉｕｍｖｅｌｖｅｔｕｍ组合带相一致,而以上两地台的化石组合产出层位可能都略高于纽芬兰东部剖面,依据Ｐｈｙｃｏｄｅｓｐｅｄｕｍ所厘定的寒武系底界?     

寒武纪大爆发与动物树的成型

由“真动物”构成的动物界（不包括海绵）通常被划分为双胚层动物、原口动物和后口动物3个亚界。寒武纪大爆发经历了爆发的前奏—序幕—主幕3个阶段,其中后两个阶段处于早寒武世初期（依次以小壳化石的首次辐射和澄江动物群爆发为代表）,另一个则发生在“寒武前夜”（即前寒武纪末期）,以伊迪卡拉生物群为代表。这次独特的三幕式大爆发分步完成了动物形态演化谱系树（简写为TOA）的成型。已有化石证据显示,动物树的3大主体或3个亚界的起源及其早期辐射分别发生于寒武纪大爆发这3个主要阶段。澄江化石库中发现的早期后口动物亚界涵盖了该亚界中所有6大分支（棘皮类、半索类、头索类、尾索类、脊椎类和绝灭了的古虫类）的原始类群,澄江动物群时代标志着寒武纪大爆发的顶峰,完成了动物树框架的成型,从而宣告了寒武纪大爆发的基本终结。其学术重要性超越了中寒武世的布尔吉斯页岩,因为前者位于动物树形成的“源头”,而后者仅代表此后的“一段流程”。在动物演化历史上4个最具转折意义的重大创新事件（即多细胞动物起源、两侧对称动物起源、后口动物起源和脊椎动物起源）中,第一个发生在伊迪卡拉纪甚至更早的时期,其余3个则可通过梅树村化石群和澄江化石群观察到其完成的主体过程。已灭绝的古虫动物门,是初具鳃裂构造的原始分节动物,作为由原口动物向后口动物过渡的一个珍稀“缺环”,很可能代表着后口动物亚界的一个根。古囊类兼有两侧对称的古虫类和一些原始棘皮动物的镶嵌体征,最可能代表棘皮动物的一个根。在早寒武世动物演化谱系中,后口动物的＂顶端类群＂的代表是被誉为“第一鱼”的昆明鱼目,目前已知包括昆明鱼、海口鱼和钟健鱼,它们具对眼、脊索与串珠状脊椎软骨共存的原始脊椎,?     

我国早期生命进化研究的进展和展望

概述了中国在晚前寒武纪——寒武纪生物化石群研究多方面(尤其是大化石)的主要成就。其中,近年发现的震旦纪陡山沱期化石生物(包括庙河生物群和蓝田植物群),对植物界的进化说来是个重要阶段;早寒武世澄江生物群(包括软躯体生物和软部保存的带骨骼生物)早于国外著名的布吉斯页岩生物群,逼近了带骨骼动物最初的爆发式辐射期。这些珍稀化石的研究将促进对早期生物进化历程的重新认识。这个研究领域有无可限量的前景。     

Shallow marine ostracode turnover in response to environmental change during the Paleocene–Eocene thermal maximum in northwest Tunisia

Two outcrop sections spanning the Paleocene–early Eocene boundary in the Sidi Nasseur–Wadi Mezaz area in northwest Tunisia provided rich ostracode assemblages, yielding 26 species of which three are newly described: Reymenticosta bassiounii, Reymenticosta nasseurensis and Buntonia? tunisiensis. The recorded ostracode fauna and associated foraminifera reflect deposition in a coastal to inner neritic environment. Many of the recorded taxa have a wide geographic distribution throughout the Middle East and North Africa. A correspondence is also observed with West African faunas, especially in the early Eocene fauna. These taxa seem to have originated in West Africa during the Paleocene and migrated northwards during the late Paleocene to early Eocene. Sea-level change and decrease in oxygenation associated with the Paleocene–Eocene thermal maximum (PETM) caused the local disappearance of the South Tethyan Paleocene fauna represented by Paracosta kefensis (morphotype-A), Paracosta aff. paleomokattamensis, Paracypris sp. B Esker, Loxoconcha saharaensis, Buntonia sp. 3 Donze et al., Protobuntonia nakkadii, and probably Reymenticosta bassiounii and R. nasseurensis. Simultaneously, a new but poorly diverse Afro-Tethyan fauna, mainly represented by Alocopocythere attitogonensis and Buntonia? tunisiensis, settled in the studied part of the basin. After the PETM, diversity increased again as various taxa (e.g. Bairdia aegyptiaca, Reticulina lamellata and Aegyptiana duwiensis) (re)appeared. Although detailed records across the P/E boundary are still sparse, it appears that the PETM exerted significant influence on the paleobiogeography and composition of Tethyan ostracode faunas.     

Benthic Cambrian biofacies of the Siberian Platform (hyoliths, small shelly fossils, archeocyaths, trilobites and calcareous algae)

The Early Cambrian history of the development of the Siberian Platform was marked by events of global significance. In the Early Cambrian the Siberian Platform was the centre of appearance of the first shelly fossils. For this reason, paleobiogeographical features of the distribution of fossils are of interest for scientists as a tool for paleogeographic and paleogeodynamic reconstructions. An analysis of changes in the Early Cambrian biota taxonomic diversity allowed us to reveal two major stages in its development: (1) Late Vendian (Tommotian and Atdabanian Stages): spreading of the Siberian biota worldwide; (2) Late Botomian-Toyonian Stages: an increase in the degree of endemism, extinction of archeocyaths, reduction in organogenic structures, deposition of black shales, and flourishing of trilobites. A permanent increase in the degree of biota endemism, which reached its maximum in the Botomian Stage, and the first appearance of migrants at the generic and species level at the same time, coincided with the first major transgressive phases. The study of the geographic distribution of diverse groups of the Early Cambrian fauna and calcareous algae of the Siberian basin allowed us to identify a number of biofacies of different age, whose boundaries do not coincide. The evolution and change in the taxonomic composition of the Siberian basin biota were affected by events of the first (Salair) phase of the Caledonian orogeny, manifested in the Altai-Sayan region much earlier than in other parts of the world and influencing the geological history of the Siberian Platform. These events resulted in the extinction and appearance of some specific groups of the Tommotian fauna in the Siberian Platform.     

A middle Cambrian shallow water trilobite fauna from the Comstock Formation,near Queenstown,western Tasmania

A limestone lens within the Comstock Formation, from low in the Tyndall Group near the Lyell Comstock Mine near Queenstown, western Tasmania, contains a small trilobite fauna. The trilobites include Ammagnostus cf. laiwuensis, Kootenia sp., Sudanomocarina? sp. and a possible member of the Monkaspidae. These suggest an age somewhere in the range from the upper Ptychagnostus atavus Zone to the Lejopyge laevigata Zone, with regional stratigraphic correlations suggesting the latter zone. This is only the second Tasmanian Cambrian fossil assemblage described from limestone; almost all previously described Tasmanian Cambrian faunas are found in siltstones and shales.     

Early Cretaceous ostracoda from the Goban Spur; D.S.D.P. leg 80, site 549

Site 549 recovered a Lower Cretaceous succession which has been shown to include parts of the Barremian and Albian stages. Forty-four species of Ostracoda are illustrated and their stratigraphic distribution used to recognise three major facies units. An high diversity inner shelf facies earlier in the Barremian gives way to a low diversity, outer shelf facies, higher in the succession. The early Albian appears to indicate a return to an inner shelf fauna. The faunas recovered have been compared to similar faunas elsewhere in N. W. Europe.