Asteroid and Ophiuroid Trace Fossils from the Lower Cretaceous of Chile

Abundant asterozoan trace fossils in the Lower Cretaceous Apeleg Formation of southern Chile were produced by the infilling of traces made by asteroids and ophiuroids on a muddy surface. Most are preserved as hypichnial ridges formed as casts on the bottom of fine-grained sandstone laminae. Star-shaped Asteriacites lumbricalis are interpreted as the infillings of shallow excavations made by asteroids. Hook-shaped and sinuous ridges of the newly defined ichnogenus and ichnospecies Ophioichnus aysenensis are interpreted as the casts of imprints made by the walking action of the arms of ophiuroids. Deposition probably took place in an offshore tide-swept marine shelf environment. In life the animals formed an assemblage equivalent to echinoderm aggregations on the modern sea floor.     

A scratch circle origin for the medusoid fossil Kullingia

Kullingia is considered a key taxon in demonstrating the presence of terminal Proterozoic-early Cambrian chondrophorine hydrozoans. However, Kullingia concentrica from the Lower Cambrian of northern Sweden possesses several features that show that it is not a body fossil but that it was formed by current or wave-induced rotation of an anchored tubular organism, possibly a sabelliditid. A scratch circle interpretation applies also to several other reports of Lower Cambrian Kullingia , including Kullingia delicata from the Chapel Island Formation of Newfoundland. Given the considerable number of problematic fossils that have been interpreted as chondrophorines, it is difficult to put an age on the oldest fossil chondrophorines, but it may be as late as the Devonian. Overall, scratch circles appear to be rarely preserved. The occurrence of these scratch circles in Lower Paleozoic storm deposits is probably related to low levels of bioturbation that enhanced both the likelihood of formation and preservation of these structures.     

Kungurian (Late Cisuralian) fusuline fauna from the Cuozheqiangma area,northern Tibet and its palaeobiogeographical implications

A fusuline fauna of seven species belonging to six genera from the lower part of the Lugu Formation in the Qiangtang Block, Tibet, is described for the first time. This fauna is assigned to the middle Kungurian based on the dominance of Cancellina primigena (Hayden). Biogeographically, the fauna is characterised by influx of many palaeoequatorial Tethyan taxa by comparison with the underlying Artinskian fauna. The palaeobiogeography of fusuline fauna in the Qiangtang Block from the Artinskian to the middle Kungurian is characterised by a pronounced transition from peri-Gondwanan affinity to a transitional affinity (Tethyan Cimmerian subregion). This transition is considered to have resulted from the combined effects among a northward drift of the Qiangtang Block, contemporaneous global climatic amelioration during the Permian, and the oceanic currents along the new-formed Neotethys Ocean.     

New data on the terrestrial gastropods from the Oligocene-Miocene transition in the Valley of Lakes, Central Mongolia

The Oligocene-Miocene terrestrial gastropod fauna of the Valley of Lakes, Central Mongolia, is described for the first time based on SEM images. These allowed detailed anatomical analyses and resulted in better species delimitation and taxonomic rectifications. The assemblage comprises six pupilloid species of the genera Gastrocopta, Vallonia, and Pupoides. Vallonia stworzewiczae Neubauer, sp. nov. is introduced as a new species. Two samples from the Loh Formation exposed at the Hotuliin Teeg locality have yielded excellently preserved specimens. Based on a small mammal fauna, these samples are proposed to span the interval of the Oligocene-Miocene boundary. A comparison with ecological requirements of modern congeners suggests the presence of rather open but vegetated habitats in the Valley of Lakes during sedimentation of the Loh Formation.     

A Middle and Late Cambrian age for the Booley Bay Formation,County Wexford,Ireland: New acritarch data and its implications

A well preserved Ediacara-type fauna was recorded for the first time a few years ago from the bases of seven sandstone beds in the type section of the Lower Palaeozoic Booley Bay Formation in County Wexford, Ireland. Four microfossil samples from mudstones interbedded with the sandstones yielded an acritarch microflora considered indicative of a late Late Cambrian age for the Ediacara fauna, thus suggesting extension of its range from the Neoproterozoic to the Late Cambrian, rather than to the Middle Cambrian as had been previously suggested. The current study examines the microfossils in more detail, with 18 samples, all of which were productive. One additional Ediacara bed approximately 100 m above those recorded earlier was also observed. The exceptionally well preserved acritarch assemblages indicate a clear Middle Cambrian age for the Ediacara beds, thus predating the previously suggested upper limit for Ediacara faunas. The uppermost part of the formation, above known occurrences of Ediacara beds, is younger; that is, early Late Cambrian, probably coeval with the Olenus trilobite zone. In addition, the age now proposed for the Booley Bay Formation shows that it is part of the Lower Palaeozoic Ribband Group of southeast Ireland, and not part of the Cahore Group as has recently been suggested by the Irish Geological Survey. Thirty-seven acritarch species (or species groups) are distinguished and illustrated. One new species, Stellechinatum ? mariatheresae Vanguestaine, is established.     

The Ediacaran Period: a new addition to the geologic time scale

The International Union of Geological Sciences has approved a new addition to the geologic time scale: the Ediacaran Period. The Ediacaran is the first Proterozoic period to be recognized on the basis of chronostratigraphic criteria and the first internationally ratified, chronostratigraphically defined period of any age to be introduced in more than a century. In accordance with procedures established by the International Commission on Stratigraphy, the base of the Ediacaran Period is defined by a Global Stratotype Section and Point (GSSP) placed at the base of the Nuccaleena Formation cap carbonate directly above glacial diamictites and associated facies at Enorama Creek in the Flinders Ranges of South Australia. Its top is defined by the initial GSSP of the Cambrian Period. The new Ediacaran Period encompasses a distinctive interval of Earth history that is bounded both above and below by equally distinctive intervals. Both chemostratigraphic and biostratigraphic data indicate that the subdivision of the period into two or more series is feasible, and this should be a primary objective of continuing work by the Ediacaran Subcommission of the ICS.     

Prod Traces (Selenichnites) from the Middle Cambrian of Morocco,with Hypotheses on the Ethology of the Tracemaker(s)

A single bedding surface was identified along the roadside close to an important road junction at Tansikht and north of Zagora in southern Morocco. This bedding plane has concomitant interference ripples and distinct horseshoe shaped concave epirelief ichnofossils dispersed across the surface. The sandstone bed belongs to the upper middle Cambrian Azlag Formation. The Azlag Formation occurs above the Bailiella Formation, with its distinctive trilobite fauna, in this section. The traces provide evidence of the ethology of an organism that was inhabiting the shallow waters during this time. Body fossils are rarely preserved in a clastic setting. The traces, assigned to the ichnogenus Selenichnites, and the new ichnospecies, Selenichnites tesiltus, are proposed, identified, diagnosed, described and illustrated herein. Possible tracemakers and behaviors are considered.     

Resolving Terreneuvian stratigraphy in subtidal–intertidal carbonates: palaeontological and chemostratigraphical evidence from the Turukhansk Uplift,Siberian Platform

Both diverse assemblages of small skeletal fossils and a representative chemostratigraphical record make the Siberian Platform widely regarded as one of the key regions for the reconstruction of global biotic and abiotic events in the late Ediacaran and early Cambrian. However, the wide distribution of intertidal–subtidal facies in the Ediacaran–Cambrian transitional strata of the central and southwestern Siberian Platform (Turukhansk–Irkutsk–Olekma facies region) produces a dramatic depletion of the palaeontological record and considerably limits their age‐calibration and long‐distance correlation. We report new lithological, palaeontological and carbonate carbon‐isotope data for the Ediacaran–Cambrian sections of the Turukhansk Uplift (northwestern Siberian Platform, western facies region). These data provide a robust framework for the chemostratigraphical correlation of the western facies region with sections of the transitional and eastern regions of the Siberian Platform and further confirms a depositional hiatus at the base of the Tommotian Stage in the stratotype section (Aldan River, SE Siberia). The carbon‐isotope curve from the Turukhansk Uplift sections correlates positively with the most chemostratigraphically representative Ediacaran–Cambrian sections (Siberia, Morocco, South China). It records major carbon‐isotope oscillations globally recognized in the lower Cambrian, enabling localization of the Fortunian and Cambrian Stage 2 boundaries in the Platonovskaya Formation. Although there is extreme paucity and poor preservation of the small skeletal fossils in the western facies region, we report individual Barskovia, Blastulospongia and chancelloriid sclerites from the Platonovskaya Formation. A combination of palaeontological and chemostratigraphical data suggests the base of P. antiqua Assemblage Zone is located in the middle Platonovskaya Formation. The earliest spiral gastropods probably occurred at ~541 Ma, as demonstrated by the discovery of a specimen of Barskovia near the base of the large negative excursion in the lower Platonovskaya Formation, correlated with the BACE negative carbon‐isotope peak in the sections of the Yangtze Platform.     

The Cambrian of Malaysia

The Cambrian of Malaysia is best represented by the quartzose Machinchang Formation in Langkawi, Kedah, northwest Peninsular Malaysia. It is divisible into three members. The oldest Hulor Member (>1260 m thick) is a coarsening upward succession of rhythmically interlayered graded siltstone, mudstone and clayey sandstone deposited as a prograded prodelta deposit. The middle Chinchin Member (>1575 m thick) is a fining upward succession of quartzose conglomerate and sandstone subdivisible into three beds. The lowest Anak Datai Bed (575 m thick) is made up of graded bedded, cross-bedded pebbly sandstone and conglomerate of estuarine channel-fills and thin to thick beds of low angle, planar cross-bedded sandstone with heavy mineral concentrations deposited as upper shoreface to beach deposits. The Temurun Bed (340 m thick) is of upper estuarine deposits of wavy-bedded sandstone and pebbly sandstone, fine tuffs and thin argillites. The upper Tengkorak Bed (>200 m thick) spans the Cambro-Ordovician boundary and consists of thick tabular bedded upper shoreface to beach fine sandstone with interbeds of fine rippled sandstone, acid tuff beds and mudstone belonging to a series of barrier beach complexes. The youngest Jemurok Member (>420 m thick) is a fining upward succession of siltstone, mudstone and hummocky cross-bedded sandstone and thin limestone deposited in storm influenced shoreface to back barrier lagoon with tidal channel environments. It has fragmentary trilobites, brachiopods, abundant trace fossils and the Kinneyian wrinkle marks.The overall sequence belongs to a highly destructive, wave-influenced delta deposit with a series of preserved beach-ridge complexes. Clastic sedimentation was reduced by peneplation of the source area as shown by the finer and thinner beds that grade into limestone of the overlying Ordovician Setul Formation.     

赣东北铅山县二叠纪雾霖山组底部含Shouchangoceras的海相动物群的发现

赣东北雾霖山组长期被视为吴家坪期的陆相沉积,在其近底部发现含Ｓｈｏｕｃｈａｎｇｏｃｅｒａｓ的海相化石群,表明该岩组并非纯陆相沉积,其底部的地层时代亦不排除茅口期晚期的可能。     

川南布拖县乌科志留纪早期介形类丽足介目(Myodocopida)

乌科剖面位于四川布拖县乌科乡境内。在此剖面的石门坎组上碎屑岩段中产有相当丰富的介形类丽足介目,特别是球茎介科的化石。经研究、鉴定,初步划分出2个属和6个种,其中包括3个新种(Entomozoe bispinosa sp.nov.,E.suboblongasp.nov.,E.wukeensis sp.nov.),1个比较种和2个未定种。在分析上述属、种,特别是相关种的地质、地理分布特征的基础上,并参考其他门类化石(如腕足类动物群)和岩石性质,提出石门坎组上碎屑岩段可能要低于笔石M.crispus带上部,大致相当于志留纪兰多维列世特列奇期早期。Entomozoe和球茎介科的最早代表推测是产自石门坎组上碎屑岩段Entomozoe的那些分子,如E.suboblongasp.nov.,而非E.tuberosa(Jones),1861(或其亲缘种E.aff.tuberosa)(Siveter et al.,1990,2006)。文中还就上述丽足介目动物群的生态环境进行了分析,指出石门坎组上碎屑岩段可能是在陆棚浅水到相对较深水、能量较低的、温暖的开阔海环境下沉积的。     

Diverse small spinose acritarchs from the Ediacaran Doushantuo Formation, South China

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.     

Elucidating Ernietta: new insights from exceptional specimens in the Ediacaran of Namibia

Exceptionally preserved specimens of Ernietta in a shallow‐marine gutter cast from southern Namibia reveal that all previously figured specimens of this iconic Ediacaran megafossil are incomplete, representing only the base of a larger and more complex organism. The complete organism is interpreted as comprising a buried, sand‐filled anchor exhibiting the classical Ernietta morphology that passes distally into a trunk that is crowned by two facing fans that extended into the overlying water column. All parts of Ernietta, from the base of its buried anchor to the tip of its fans, appear to have been composed of a palisade of tubular elements that have been variably preserved. Similarity of tubule morphology despite the inherent difference in function between these constructions supports the view that these tubes were integral to all anatomical parts and functions of Ernietta. This style of architecture, construction and function is unique to the Erniettomorpha, supporting the view that it represents an extinct Ediacaran clade in the early evolution of multi‐cellular life.     

湖北三峡地区埃迪卡拉系灯影组Hiemalora stellaris生物属性及埋藏分析

Hiemalora stellaris是湖北宜昌三峡地区埃迪卡拉系灯影组石板滩生物群中数量最为丰富的化石类型之一,由位于中心位置的圆盘和围绕盘缘向外伸出的似触手状结构组成,似触手状结构长度与圆盘直径具有较好相关性。同时也发现少量Hiemalora与茎干相连,其中一枚产自石板滩段底部的标本保存完整,与茎干连接有叶状体。叶状体呈卵形,可见一级分枝与二级分枝,顶部有呈"牛角状"的尖刺,叶状体形态与Charniodiscus spinosus相似。结合纽芬兰地区发现的Primocandelabrum hiemaloranum,表明Hiemalora作为生物体的固着器官,起到抵御水流冲刷、支撑和固定整个生物体的作用,但与其相连的叶状体表现出不同的形态类型,表明Hiemalora化石可能具有较为多样的生物来源。根据化石的形态特征和埋藏状态分析,Hiemalora在生物生活时位于藻席层之下的沉积物内,常呈正凸起保存于岩层顶面,而茎干和叶状体位于水体中,生物死亡后,叶状体倒伏在藻席层之上,当岩层沿藻席层劈开后,在顶面保存为凹陷的印痕。     

论陡山沱组的年代

三峡地区震旦系的三层式地层结构 (冰积层 ,陡山沱组特色的大型带刺疑源类组合层 ,埃迪卡拉生物化石层 )在世界其它地区是常见的。通过生物和化学地层对比我们认为陡山沱组及其化石组合层是在马雷诺恩 ( Marinoan)冰期之后、埃迪卡拉生物群分异之前沉积的。根据这一地层对比方案以及西伯利亚、纳米比亚和阿瓦龙半岛 ( Avalon Peninsula)新元古代地层的精确放射性同位素测年资料 ,陡山沱组的沉积年龄很可能在五亿五千万年至六亿年之间。这一估计要新于以前发表的铷锶法或钾氩法测定的陡山沱组黑色页岩或海绿石年龄。更精确地估算陡山沱组的沉积年龄还有待于在陡山沱组地层中发现火山灰以及对火山灰的精确年龄测定 ,但我们根据地层对比估算的陡山沱组年龄 ,为评估庙河和瓮安陡山沱组生物群的演化意义提供了必要的地层框架。     

Geological significance of the discovery of Middle Triassic (Ladinian) radiolarians from the Hong Hoi Formation of the Lampang Group,Sukhothai Zone,northern Thailand

This paper presents a newly found fauna of Ladinian (Middle Triassic) radiolarians from the Hong Hoi Formation of the Lampang Group, Sukhothai Zone, northern Thailand. The Ladinian age determined by the radiolarian fauna concords with the age previously determined by mollusks. The study section consists of intercalated sandstone and shale in the lower part and a thick conglomerate in the upper part. The radiolarian-bearing siliceous beds are intercalated within the lower unit. The lithic sandstone of the lower unit consists mainly of volcanic rock fragments, quartz, and feldspar, whereas the thickly bedded conglomerate of the upper unit is characterized by abundant gravel-sized clasts of volcanic rock and limestone. These lithic features of the study section suggest that during deposition the Hong Hoi Formation was located near a supply of volcanic materials. A forearc basin close to the Sukhothai Arc would be the most suitable environment for the deposition. The Ladinian age determined by the radiolarian fauna supports the occurrence of intensive volcanic activity within the Sukhothai Arc during the Middle Triassic.     

WUCHIAPINGIAN (LOPINGIAN, LATE PERMIAN) BRACHIOPODS FROM THE EPISKOPI FORMATION OF HYDRA ISLAND, GREECE

Abstract:  Twenty-three species of silicified brachiopods are described from four samples in the middle and upper parts of the Episkopi Formation from Hydra Island, Greece. These brachiopods are newly recorded from the region and together with previously described brachiopods from the same localities constitute the most diverse Lopingian (Late Permian) brachiopod fauna reported in southern Europe. The brachiopod fauna is Wuchiapingian as indicated by the associated conodonts. The fauna from Hydra exhibits strong palaeobiogeographical links with the faunas from South China. In addition, palaeobiogeographical affinities with the faunas of Thailand and the northern peri-Gondwanan region are also present, which implies a peri-Gondwanan origin for Hydra. Palaeoecologically, the brachiopod assemblage from sample EP in the middle part of the Episkopi Formation is dominated by pedically-attached and cementing genera and reflects moderate energy conditions above storm wave base and an abundance of hard substrates provided by sponges in the biohermal habitat. By contrast, the brachiopod assemblage in the other three samples from the upper part of the Episkopi Formation is dominated by spinose genera with a free-resting life habit, suggesting soft substrates in a quiet water environment below storm wave base on the outer part of the shelf. New taxa are Petinospiriferina gen. nov., Hustedia episkopiensis sp. nov., Waterhouseiella hydraensis sp. nov. and Xenosaria tenuis sp. nov.     

Late Late Cambrian Trilobites From Near Birch Inlet, South-Western Tasmania

The first late Late Cambrian basinal-facies trilobites to be described from Tasmania are from a succession exposed 8.5 km west of Birch Inlet, south-western Tasmania. Twenty-one taxa are described; the six agnostoid species include a new species of Leiagnostus, L inletensis. The polymeroids include five new species: Hedinaspis uniformis, Proceratopyge longa, Niobella birchensisSkljarella expansa and Ivshinaspis reticulata.SkljarellaIvshinaspis are described for the first time from Australia. The specimens are preserved in siltstone belonging to a basinal facies; the fauna has more in common with those of the South-East China Faunal Province than with the shallow-water carbonate-facies faunas from northern Australia. The fauna is of late Late Cambrian age (Payntonian–earliest Datsonian) on the north Australian biostratigraphic scale. The Birch Inlet fauna is correlated with those of the Siyangshan Formation of Zhejiang, the Guoziguonen Formation of Xinjiang and the Shengjiawan Formation of Hunan. There are similarities with late Late Cambrian faunas from Nevada, Kazakhstan and New Zealand. K ey words : Trilobita, Late Cambrian, Tasmania, basinal facies, biostratigraphy, palaeobiogeography.     

Integrated sedimentological,ichnological and sequence stratigraphical studies of the Koti Dhaman Formation (Tal Group), Nigali Dhar Syncline,Lesser Himalaya,India: paleoenvironmental,paleoecological, paleogeographic significance

Abstract

Integrated ichnology, sedimentology and sequence stratigraphy of the Lower Quartzite Member to the Arkosic Sandstone Member of the Koti Dhaman Formation (Cambrian Series 2, Stage 4), Tal Group, Nigali Dhar Syncline, Lesser Himalayan lithotectonic zone are presented. Trilobite traces of Gondwanan affinity i.e., Cruziana salomonis, Cruziana fasciculata, Rusophycus dispar and Rusophycus burjensis are recorded along with Arenicolites isp. and Skolithos isp. from the Lower Quartzite Member. A rich and diverse ichnoassemblage attributed to the Cruziana ichnofacies is described for the first time from the Arkosic Sandstone Member of the same formation. Seven ichnofossil assemblages, i.e., Cruziana-Rusophycus, Planolites-Palaeophycus, Cruziana problematica, Diplichnites, Cochlichnus anguineus, Bergaueria perata and Psammichnites gigas have been recognized in the Lower Quartzite to Arkosic Sandstone members of the Koti Dhaman Formation. Seven sedimentary facies i.e., sandstone–shale facies (FT1), cross-bedded (trough and planar) sandstone (FT2), bedded sandstone facies (FT3), shale facies (FT4), shale–sandstone facies (FT5), shale-rippled sandstone facies (FT6) and planar and trough cross-laminated sandstone (FT7) and four facies associations FA1-FA4 are identified in the Koti Dhaman Formation. The formation contains shallowing upward parasequences of a tidal flat complex. Overall, two major events are recognized: i) the break in sedimentation between the Lower Quartzite Member and the overlying Shale Member probably related to forced-regressive event and ii) the facies shift from FT6 to FT7 of the Arkosic Sandstone Member represents an erosive transgressive event; the surface is interpreted as wave ravinement surface, which also serves as a sequence boundary. Integrated ichnology, sedimentology and sequence stratigraphic studies indicate that the Lower Quartzite Member was deposited in a shallow subtidal sand sheet complex and tidal flat complex; the Shale Member was deposited in a mud flat setting of a tidal flat complex, and the Arkosic Sandstone Member in a mixed-flat (tidal flat complex) to sand sheet complex front and margin (subtidal sand sheet complex). Overall, the lower to middle part of the Koti Dhaman Formation represents a tide-dominated shallow subtidal–intertidal to mud-flat subenvironments of the tidal flat complex. A palaeogeographic reconstruction of lower Cambrian (516–514?Ma) is presented based on the distribution of trilobite traces from the Lesser Himalaya and the Bikaner–Nagaur area of Peninsular India (eastern Gondwana), Egypt, Jordan, Turkey (western Gondwana) and Canada (Avalonia).