Paleoecological and paleobiogeographic considerations of Ordovician graptolites from the Cordillera Oriental,Jujuy Province,Argentina

We analyse new paleoecological data from South American graptolite records to understand the patterns that influence the space-tempo distribution of the group. A cluster analysis including taxa from the Baltograptus cf. B. deflexus and Didymograptellus bifidus Zones is carried out to evaluate the paleogeographic relationships between north-western Argentina and the other regions in the world. Three different biofacies were recognised in the Acoite Formation. The first biofacies takes place in the lower part of the unit, corresponding to pelitic levels (Tetragraptus phyllograptoides and Tetragraptus akzharensis Zones), and it is represented by pandemic forms. The other two biofacies belong to the endemic or neritic shallow water environments, and develop in deposits corresponding to the middle part of the Acoite Formation (bottom of the Baltograptus cf. B. deflexus Zone) in the Sierra de Aguilar, and in the upper half of the unit exposed in the Los Colorados area (D. bifidus Zone), respectively. The statistical analysis highlight the paleobiogeographic relationship between north-western Argentina and south-western China during the middle-upper Floian (Baltograptus cf. B. deflexus and D. bifidus Zones), and it supports the hypothesis that during the Early Ordovician north-western Argentina was located in the middle to high latitudes, included in the cold water faunal realm.     

Volkhov graptolites from the lower-middle Ordovician boundary beds of the St. Petersburg region,Russia

The lower and lowermost Middle Ordovician strata of the Volkhov Stage exposed in the vicinity of St. Petersburg, Russia, yield a graptolite fauna at several stratigraphic levels, being more often confined to the mud-mound clays than to the normally stratified, Condensed carbonates. Overall taxonomic diversity of the Volkhov graptolites is relatively low and associations include no more than seven species in ail localities. TheTetragraptus, Didymograptus andXiphograptus species found are pandemic and have quite extensive stratigraphie ranges within the mid-Arenig Series. Based on the graptolite zonation, the Volkhov Stage can be correlated to thePseudophyllograptus angustifolius elongatus andDidymograptus (Expansograptus) hirundo graptolite biozones of Baltoscandia and to the upperDidymograptus simulans toDidymograptus (Expansograptus) hirundo biozones of the British graptolite succession. TheIsograptus victoriae lunatus lower zonal boundary probably falls within the graptolite-bearing interval of the lower Volkhov Stage. As the result of indirect biostratigraphic and interpretative lithological correlations, the first appearance ofUndulograptus austrodentatus at the base of the Darriwilian Stage is deemed to be close to the boundary of theMegistaspis simon andM. limbata trilobite biozones and the lowerBaltionodus norrlandicus conodont Biozone of the upper Volkhov Stage. Seven dichograptid species belonging to four genera are described, one of them,Azygograptus volkhovensis n. sp., new.      

Tremadocian (Ordovician) biostratigraphy and graptolites at Dayangcha (Baishan,Jilin, NE China)

Based on a systematic study of Tremadocian graptolites from the Early Ordovician Yehli Formation at Dayangcha, Baishan of Jilin, NE China, a revised graptolite zonation is proposed for the Tremadocian rocks in the area. In ascending order, the graptolite zones include theRhabdinopora flabelliformis parabola Zone, theAnisograptus matanensis Zone, thePsigraptus jacksoni Zone and theAorograptus victoriae Zone. The first three zones are discussed with their definitions and durations clarified, whereas the last zone is introduced for the first time as a replacement of the formerAdelograptus-Clonograptus Zone. The entire Yehli Formation is considered to be older than the late Tremadocian Hunneberg Substage of Scandinavia, the latter being represented by the carbonate-dominated basal part of the overlying Liangchiashan Formation where no graptolites have so far been discovered. The Tremadocian succession in the Dayangcha area is regarded as being representative of the North China (Sino-Korea) Palaeoplate, and a correlation of the Tremadocian graptolite sequence with those of other continents is suggested. Nine species belonging toDendrograptus, Aspidograptus, Callograptus andAirograptus of the family Dendroidae, and eight species ofPsigraptus, Adelograptus, Aorograptus andKiaerograptus of the family Anisograptidae are described and some are revised in the present paper. Among the important revisions are the reconstructed proximal development ofPsigraptus jacksoni based on partially three-dimensional specimens from the area, and the complex thecal structures ofAspidograptus.      

内蒙古乌海大石门奥陶系牙形刺和Histiodella动物群发现的意义

本文描述了内蒙古乌海大石门剖面奥陶系的牙形刺动物群:下克里摩里组主要有Histiodella kristinae,H.holodentata,H.wuhaiensis sp.nov.,Polonodus newfoundlandensis和Paroistodus horridus等,应归属于中奥陶统达瑞威尔阶(Darriwilian)之Histiodella kristinae带,并在同一剖面上与笔石Pterograptus elegans带和Didymograptus murchisoni带下部相当;下克里摩里组顶部产Histiodella kristinae,Baltoplacognathus cf.reclinatus,Periodon aculeatus和Protopanderodus rectus等,所以大石门剖面的Histiodella kristinae带顶部可能已与北欧Pygodus serra带之底部相当;乌拉力克组底部的砾状灰岩透镜体产有牙形刺Pygodus anserinus?,Protopanderodus liripipus,Yangtzeplacognathus protoramosus和Dapsilodus viruensis等,其中Pygodus anserinus?Pa分子(器官种的一组成分子)的口面瘤齿列的瘤齿比较粗糙,与典型的Pygodus anserinus稍有不同,且在牙形刺十分丰富的样品中仅有一枚此种之Pa分子,所以本文尚有疑问地把这层砾状灰岩归入Pygodus anserinus带,同时不能排除把它归入Pygodus serra带顶部Yangtzeplacognathus protoramosus亚带的可能。由于此剖面牙形刺化石与丰富的笔石共生,为牙形刺带与笔石带的精确对比提供了直接证据。Histiodella动物群在此剖面的发现,不仅具有十分重要的地层意义,而且具有明显的岩相古地理意义。本文详细描述了新种Histiodella wuhaiensis并讨论了Histiodella属5个种之区别。     

Horizon of the oldest known bryozoans (Ordovician)

Among the six species of fossil bryozoans described by Xia et al. [Xia, F.S., Zhang, S.G., Wang, Z.Z., 2007. The oldest bryozoans: new evidence from the late Tremadocian (Early Ordovician) of East Yangtze Gorges. Journal of Paleontology 81 (6), 1308–1326] from the Fenghsiang Formation of the Chenjiahe section of Yichang and the Guanzhuangping section, Liujiachang Town of Songzi, the Yangtze Gorges, Nekhorosheviella nodulifera occurs in the pristinus Conodont Subzone (lower Subzone of deltifer Conodont Zone) and the five other species are associated with the conodont Paltodus deltifer deltifer and the graptolites Acanthograptus sinensis and A. erectoramus. Based on the conodonts and graptolites, this bryofauna stratigraphically corresponds to the A. sinensis Graptolite Zone or P. deltifer Conodont Zone. The bryofauna is of Tremadocian Age (Early Ordovician) and represents the oldest bryozoans so far as known.     

The Lerhamn drill core and its bearing for the graptolite biostratigraphy of the Ordovician Tøyen Shale in Scania,southern Sweden

Maletz, J. & Ahlberg, P. 2011: The Lerhamn drill core and its bearing for the graptolite biostratigraphy of the Ordovician Tøyen Shale in Scania, southern Sweden. Lethaia, Vol. 44, pp. 350–368. A drill core through the Lower Ordovician Tøyen Shale Formation at Lerhamn, NW Scania, southern Sweden, provides important new information for the precise biostratigraphic resolution of the Floian to lower Darriwilian time interval in southern Scandinavia. The Hunnegraptus copiosus, Tetragraptus phyllograptoides, Cymatograptus protobalticus (new), Baltograptus vacillans (new), Baltograptus sp. cf. Baltograptus deflexus (new), Baltograptus minutus (new), Isograptus victoriae, Undulograptus austrodentatus (Arienigraptus zhejiangensis and Undulograptus sinicus Subzones) and the (?)Corymbograptus retroflexus (new) biozones are differentiated in the core and their correlation in Scania is discussed. The Lerhamn drill core provides the most detailed graptolite record of the Floian Stage in Scandinavia. The interval is dominated by a number of species of the genus Baltograptus, endemic to the Atlantic Faunal realm and highly useful for regional biostratigraphic correlation. The biostratigraphic framework is based on endemic and pandemic faunal elements. The mixture of both elements in the drill core allows a more precise inter‐continental correlation of Lower to Middle Ordovician graptolite faunas and may – in the future – provide information as to the climatic history of regions dominated by Baltograptus faunas in the Floian. The (?)C. retroflexus Biozone is based on species originally described from Bohemia, but the record of the zone in the Lerhamn drill core indicates a wider distribution of its fauna. □Biostratigraphy, graptolites, Ordovician, Scania, Sweden.     

Katian (Upper Ordovician) conodonts from Wales

Middle and upper Katian conodonts were previously known in the British Isles from relatively small collections obtained from a few localities. The present study is mainly based on 17 samples containing more than 17 000 conodont elements from an approximately 14‐m‐thick succession of the Sholeshook Limestone Formation in a road cut near Whitland, South Wales, that yielded a diverse fauna of more than 40 taxa. It is dominated by representatives of Amorphognathus, Aphelognathus/Plectodina and Eocarniodus along with several coniform taxa. Representatives of Decoriconus, Istorinus and Sagittodontina are reported from the Ordovician of UK for the first time. The fauna is a typical representative of the British Province of the Atlantic Realm and includes a mixture of taxa of North American, Baltoscandic and Mediterranean affinities along with pandemic species. Based on the presence of many elements of Amorphognathus ordovicicus and some morphologically advanced specimens of Amorphognathus superbus, the Sholeshook Limestone Formation is referred to the lower A. ordovicicus Zone. Most of the unit is also coeval with Zone 2 of the Cautleyan Stage in the British regional stage classification, and stage slice Ka3 of the middle Katian Stage in the global stratigraphical classification, an age assignment consistent with data from trilobites, graptolites and chitinozoans. The unusually large collection of M elements of Amorphognathus provides insight into the complex morphological variation in this element of some Katian species of this genus. The Sholeshook conodont fauna is similar to those of the Crûg and Birdshill limestones, but differs in several respects from the slightly older ones from the Caradocian type area in the Welsh Borderland. Although having some species in common, the Sholeshook conodont fauna clearly differs from coeval Baltoscandic faunas and is even more different in composition compared with equivalent North American Midcontinent faunas.     

The graptolite correlation of the North American Upper Ordovician Standard

The North American Upper Ordovician reference standard, the Cincinnatian Series, contains rich shelly microfossil faunas in its type area in the Cincinnati Region but graptolites are uncommon in most of its shallow-water calcareous sediments. Consequently, the graptolite correlation of this key sequence has remained uncertain, in part, even controversial. A review of both previously published recently discovered graptolite Occurrences in the type Cincinnatian, combined with data from the important graptolite successions in Oklahoma New York-Quebec, has not only clarified the graptolite correlation of the Cincinnatian but also added new data on the morphology taxonomy, the vertical horizontal distribution, of several taxa. The information now at hand indicates that the Edenian Stage correlates with the C. spiniferus Zone, the Maysvillian Stage with the C. pygmaeus lower middle P. manitoulinensis Zone, the Richmondian Stage with the upper P. manitoulinensis , the D. complanatus , possibly part of the C. inuiti Zone. Comparison between graptolite conodont biostratigraphic evidence reveals no apparent conflict. Correlations are proposed between Upper Ordovician North American stages, graptolite conodont zones, successions in Texas, Oklahoma, Sweden, European graptolite zones, British series.     

Reef reconstruction after extinction events of the latest ordovician in the Yangtze platform,South China

Summary Early Silurian reef reconstruction on the Yangtze Platform, in the northern part of the South China Block, is preceded by a combination of regional and global processes. During most of Ashgill time (Late Ordovician), the area was dominated by Wufeng Formation deep water graptolitic black shales. Reefs largely disappeard in the middle of the Ashgill Stage, from the northwestern margin of Cathaysian Land (southeastern South China Block), in advance of the Late Ordovician glaciation and mass extinction, due to regional sea-level changes and regional uplift, unrelated to the mass extinction itselt. Late Ordovician microbial mudmound occurrence is also found in the western margin of the Yangtze Platform, its age corresponding to theDicellograptus complexus graptolite biozone of pre-extinction time. On the Yangtze Platform, a thin, non-reef-bearing carbonate, the Kuanyinchiao Formation (=Nancheng Formation in some sites), thickness generally no more than 1m, occurs near several landmasses as a result of Hirnantian regression. Reappearance of the earliest Silurian carbonates consisting of rare skeletal lenses in the upper part of Lungmachi Formation, are correlated to theacensus graptolite biozone, early Rhuddanian of Shiqian, northeastern Guizhou, near Qianzhong Land. Carbonate sediments gradually developed into beds rich in brachiopods and crinoids in the lower part of Xiangshuyuan Formation, middle Rhuddanian. In the middle part of Xiangshuyan Formation, biostromes, containing abundant and high diversity benthic faunas such as corals, crinoids and brachiopods, show beginnings of reconstruction of reef facies. Substantial reef recovery occurred in the upper part of Xiangshuyuan Formation, lower Aeronian, as small patch reefs and biostromes. During the late Aeronian, carbonate sediments, especially reefs and reef-related facies, expanded on the upper Yangtze Platform, and radiation of reefs occurred in Ningqiang Formation, upper Telychian. The long period of reef recovery, taking several million years, remains difficult to explain, because redistribution of any refugia faunas would be expected to take place soon after the extinction. Reefs and reef-related facies subsequently declined after Telychian time due to regional uplift of the major portion of the Yangtze Platform. Carbonate facies are therefore uncommon in South China during the rest of Silurian time.     

河北唐山下奥陶统牙形刺生物地层的新认识

本文作者在安太庠等(1983)研究过的唐山赵各庄剖面,对下奥陶统冶里组和亮甲山组较系统地采集了牙形刺样品,通过对所获牙形刺标本和安太库等(1983)所描述的牙形刺动物群仔细研究后,对包括分带和对比意见有新的认识。安太庠等(1983)把自寒武系凤山组顶部至下奥陶统亮甲山组这段地层,自下而上建立了Cordylodus proavus,Utahconus beimadaoensis-Monocostodus sevierensis,Cordylodus rotundatus-"Acodus"oneotensis,Scolopodus quadraplicatus-S.opimus,Scalpellodus tersus,Serratognathus bilobatus,S.extensus和Paraserratognathus paltodiformis等8带,其中Cordylodus proavus带为寒武系顶,Utahconus beimadaoensis-Monocostodus sevierensis至Scolopodus quadraplicatus-S.opimus等带为下奥陶统冶里组,其余则为下奥陶统亮甲山组,寒武系-奥陶系界线置于Utahconus beimadaoensis-Monocostodus sevierensis带之底。这一牙形刺序列和寒武系-奥陶系界线划分方案在国内被广泛引用至今(王志浩等,2011)。本文通过补充采集到的牙形刺标本和安太庠等(1983)报道的材料,根据一些重要分子在地层中的分布及公认的牙形刺分带原则,对安太庠等(1983)的牙形刺分带方案重新修订,自下而上修订为Cordylodus proavus,C.lindstromi,Iapetognathus jilinensis,Cordylodus angulatus,Chosonodina herfurthi-Rossodus manitouensis,Glyptoconus quadraplicatus,Scalpellodus tersus-Triangulodus aff.bifidus,Serratognathus bilobatus,S.extensus和Paraserratognathus obesus等10带,寒武系-奥陶系界线则置于Iapetognathus jilinensis带之底。根据这一修订后的牙形刺序列,寒武系顶至下奥陶统冶里组部分的牙形刺带可与国内、外相同层位的牙形刺带进行精细对比,而亮甲山组的牙形刺虽有明显的地方性特点,但除其顶部因更具地方性而不能直接对比外,其中下部仍可与华南区下奥陶统红花园组相对比。     

Ammonites of Tethyan origin from the Ryazanian of the Russian platform: Genus <Emphasis Type="Italic">Subalpinites</Emphasis> Mazenot

The ammonite genus Subalpinites is known from the Berriasian of southern and central Europe, North Africa, Mangyshlak, and Ryazanian Stage of Central Russia. New species are described: S. gruendeli sp. nov., S. faurieformis sp. nov., S. remaneiformis sp. nov. These species and also S. krischtafowitschi Mitta characterize the lower subzone of the Riasanites rjasanensis Zone in the Moscow Region. The upper subzone of this zone in the Ryazan Region contained members of Subalpinites identified in open nomenclature.     

Didymograptus bifidus and the trans-Atlantic correlation of the Lower Ordovician

Bergström, S. M. & Cooper, R. A.: Didymograptus bi'us and the trans-Atlantic correlation of the Lower Ordovician.
The co-occurrence of Didymograptus bifidus (Hall) and Prioniodus mae Lindstrom, and other conodonts of the middle Arenigian P. mae Zone in the upper part of the Marathon Limestone, Texas, provides the first non-graptolitic evidence that at least part of the D. bifidus Zone, as recognized in the reference area for the standard graptolite zonal succession of the Ordovician of North America, is as old as the BritisK D. nitidus Zone. This has important implications for the correlation of Early Ordovician rocks within North America and across the Atlantic. A regional review of the available evidence from conodonts and shelly megafossils indicates that the D. bifidus—D. artus graptolite assemblage widely used for identification of the D. bifidus Zone in North America ranges in age from the middle Arenigian to, probably, the lower Llanvirnian, and hence is of relatively limited use for precise local and regional correlations. It is also noted that the base of the North American Middle Ordovician falls within hograptus 'caduceus' Zone strata that apparently correspond to an interval in the middle to upper part of the British D. hirundo Zone.     

Revision of the Zone 13 graptolite biostratigraphy in the Marathon, Texas, standard succession and its bearing on Upper Ordovician graptolite biogeography

One of the long-standing problems in North American graptolite biostratigraphy is the distinct differences in assemblages of post-Climacograptus bicornis age between the classical graptolite sequences in the New York - Quebec and Marathon, west Texas, regions. These have been attributed either to faunal provincialism or to the presence of a major hiatus between the Woods Hollow and Maravillas formations in Texas. New collections from the key Marathon Picnic Grounds section contain diagnostic Late Ordovician graptolites that confirm the existence of a major stratigraphic gap below the Maravillas Formation. The lower Maravillas Formation (Zone 13) has a Late Ordovician, low-diversity Pacific Province graptolite fauna that includes the biostratigraphically diagnostic species Climacograptus nevadensis, C. tubuliferus, Orthograptus fastigatus and Dicellograptus ornatus. Zone 13 graptolite assemblages from the Marathon region correlate with the C. tubuliferus to D. ornatus zones in the Trail Creek, Idaho, succession, the Ea4-Bo2 interval in Victoria, the O. fastigatus Zone in the Canadian Arctic Islands, the O. quadrimucronatus to D. ornatus zones of the Canadian Cordillera, and the D. complanatus to D. anceps zones in Scotland. The hiatus between the Woods Hollow and Maravillas formations spans an interval corresponding to at least the Eal Ea3 interval in Australia, the C. americanus to upper A. manitoulinensis zones in the New York - Quebec succession, and the D. clingani and P. linearis zones in Scotland. These results agree with the magnitude of the hiatus previously indicated by conodont biostratigraphy. Late Ordovician graptolite distribution patterns in North America can be explained by an extension of Cooper, Fortey & Lindholm's (1991; Lethaia 24) Lower Ordovician graptolite biofacies model into the Upper Ordovician, which incorporates both lateral water-mass specificity and depth stratification. Using this model, we recognize in Laurentia two separate biofacies among tropical-zone Late Ordovician Pacific Province graptolite faunas, a cosmopolitan Oceanic biofacies, and a cratonic Laurentian biofacies. The lower Maravillas Formation graptolite fauna is clearly part of the Oceanic biofacies, whereas the coeval Appalachian faunas represent the Laurentian biofacies. □Graptolites, Ordovician, biostratigraphy, Texas, biofacies, biogeography.     

Sheinwoodian (Silurian) conodonts and graptolites from NE Anti‐Atlas,Morocco

Männik, P., Loydell, D.K. & Lubeseder, S. 2010: Sheinwoodian (Silurian) conodonts and graptolites from NE Anti‐Atlas, Morocco. Lethaia, Vol. 44, pp. 410–416. Conodonts and graptolites from a limestone at the base of the Tamaghrout Formation indicate that this is of early Wenlock age. This is the first unequivocal dating of a Sheinwoodian limestone from Morocco. All of the conodonts are known also from several other regions and suggest that there was no major difference in conodont faunas in northern Gondwana, Baltica and Laurentia at this time. Biostratigraphy, conodonts, graptolites, Morocco, Silurian, Sheinwoodian.     

川东北二叠纪吴家坪期牙形石（刺）序列及其世界对比

对四川省宣汉县渡口和南江县桥亭吴家坪期地层的系统采集和研究结果表明,吴家坪期至少包括７个牙形石带,自下而上为Ｃｌａｒｋｉｎａｄｕｋｏｕｅｎｓｉｓ带,Ｃ．ａｓｙｍｍｅｔｒｉｃａ带,Ｃ．ｌｅｖｅｎｉ带,Ｃ．ｇｕａｎｙｕａｎｅｎｓｉｓ带,Ｃ．ｔｒａｎｓｃａｕｃａｓｉｃａ带,Ｃ．ｏｒｉｅｎｔａｌｉｓ和Ｃ．ｉｎｆｌｅｃｔａ带。其中,前３个带的层位低于一直作为吴家坪期早期的Ｃ．ｌｉａｎｇｓｈａｎｅｎｓｉｓ带。吴家坪阶的顶界以置于Ｃ．ｉｎｆｌｅｃｔａ带与Ｃ．ｓｕｂｃａｒｉｎａｔａ带之间较妥。同时,建立了Ｃｌａｒｋｉｎａｄｕｋｏｕｅｎｓｉｓ,Ｃ．ａｓｙｍｍｅｔｒｉｃａ,Ｃ．ｂｉｚａｒｒｅｎｓｉｓ,Ｃ．ｄａｘｉａｎｅｎｓｉｓ,Ｃ．ｄｅｍｉｃｏｒｎｉｓ,Ｃ．ｉｎｆｌｅｃｔａ,Ｃ．ｌｏｎｇｉｃｕｓｐｉｄａｔａ等７个新种。     

Ammonites of Tethyan origin in the Ryazanian stage of the Russian platform: Genus <Emphasis Type="Italic">Riasanella</Emphasis> gen. nov.

A new ammonite genus Riasanella is described from the Ryazanian Stage of the Russian Platform (type species R. rausingi sp. nov.). The new species R. plana sp. nov., R. olorizi sp. nov., and R. riasanitoides sp. nov. are described. These species come from the lower, strongly condensed beds of the Riasanites rjasanensis Zone of the Moscow Region. The upper subzone of this zone in the Ryazan Region contains specimens of Riasanella, identified in open nomenclature. The new genus is assigned to the family Himalayitidae; one of its species is a possible ancestor of Riasanites Spath.     

LUNGMACHI FORMATION GRAPTOLITES FROM SANLANGPU OF XIXIANG, SOUTHERN SHAANXI

The specimens referred to the Lungmachi Formation graptolites in the present paper were collected from Sanlangpu of Xixiang, Southern Shaanxi, consisting of 8 genera and 51 species or subspecies including 12 new species (see Table l in the Chinese text). This paper describes only the new species, with the rest being shown in tablesand plates. According to the present data on hand, the Lungmachi Formation graptolites studied here may be divided into 4 zones as follows:4. Orthograptus vesiculosus Zone (L_3)3. Parakidograptus acuminatus Zone (L_2)2. Glyptograptus persculptus Zone (L_1)1. Diplograptus bohemicus Zone (W_6)The first graptolite zone belongs to the Upper Ordovician, while the others to the Lower Silurian, indicating that the Lungmachi Formation in our studied area is a lithostratigraphic unit stridling across the Ordovician-Silurian boundary.This paper is in commemoration of the respectable late Prof. Mu En-zhi, to whom the writers are very much obliged for his kindness inguiding their scientific researches.     

EARLY ORDOVICIAN CONODONTS FROM TARUTAO ISLAND,SOUTHERN PENINSULAR THAILAND

Abstract: Early Ordovician conodont faunas of the Thung Song Formation on Tarutao Island, southern peninsular Thailand, consist of 14 known species belonging to 17 genera, and eight undescribed species. Utahconus tarutaoensis and Filodontus tenuis are new species. Three conodont zones: the Rossodus manitouensis Zone, the Utahconus tarutaoensis Zone and the Filodontus tenuis Zone, in ascending order, are defined in the study sections. These are coeval with the interval from the Rossodus manitouensis Zone to the Acodus deltatus‐Oneotodus costatus Zone of the standard zonation in the North American Midcontinent. Based on the conodonts studied here and fossils previously reported from Tarutao Island, the Thung Song Formation is early Tremadocian to middle Arenig (Ibexian) in age. This formation is lithostratigraphically subdivided into the S1 to S5 members, and our study sections consist of the S1 to S3 members. These strata accumulated on a shelf in the Early Ordovician. The depositional environments of the limestones making up the S1 and S3 members were in deeper‐shelf conditions. Limestone and shale of the S2 member formed in a shallow‐water, high‐energy environment.     

The oldest Ordovician foraminifers (Oepikodus evae conodont Zone, Floian) from South America

The oldest occurrences of the monothalamous foraminifer species Amphitremoida longa Nestell and Tolmacheva and A. laevis Nestell and Tolmacheva are found in the San Juan Formation together with conodonts of the Oepikodus evae Zone of the Floian (Lower Ordovician), in the Salagasta 2 section, southern Precordillera, Argentina. These discoveries represent the oldest record for foraminifers in South America. The foraminifers, species of which were originally described from the Lower Ordovician of northwestern Russia, are found in shallow high energy carbonate platform deposits in the Precordillera, together with a North Atlantic province conodont fauna. The carbonate sequence of the San Juan Formation in the Salagasta region is interpreted as a succession ranging from shallower tidal deposits to carbonate crinoidal shoaling bar deposits.     

湖北宜昌远安真金和界岭奥陶系牯牛潭组顶部的牙形刺及其地层意义（英文）

本文描述了采自湖北宜昌远安真金和界岭剖面奥陶系牯牛潭组顶部的牙形刺,它们有Baltoniodus prevariabilis,Drepanoistodus venustus,Panderodus gracilis,Periodon aculeatus,Protopanderodus calceatus,P.varicostatus?,Yangtzeplacognathus foliaceus和Y.protoramosus等,确认宜昌地区牯牛潭组顶部应归属于奥陶系达瑞威尔阶Pygodus serra带之Yangtzeplacognathus protoramosus亚带,并可与宜昌黄花场剖面和南京汤山外杆沟剖面同名组顶部及新疆柯坪羊吉坎剖面一间房组顶部的牙形刺带相对比。同时,它要比重庆城口大槽剖面牯牛潭组顶部的牙形刺带低3个带(Pygodus anserinus带至Baltoniodus variabilis带),这一事实也说明了牯牛潭组顶部在中国扬子地台的穿时性。