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Restudy of Proexenocrinus inyoensis Strimple and McGinnis, 1972, shows that this earliest-known rhodocrinitid diplobathrid camerate crinoid (late Floian, Early Ordovician) expresses the only known record of ambulacral floor plates within pinnules. These pinnule floor plates are remarkably conserved plesiomorphic expressions, with anatomy similar to floor plates of some of the earliest pentaradiate echinoderms, although on a smaller scale. Proexenocrinus floor plates provide direct skeletal evidence that the general resemblance of blastozoan (eocrinoid, diploporan, rhombiferan) brachioles and crinoid pinnules is the product of homoplasy. Proexenocrinus posterior cup morphology is interpreted to include an anitaxis, a distinctive posterior interray morphology. [ABSTRACT FROM AUTHOR]

Abstract Source rocks in Lower Cambrian (Є 1) and Middle-Upper Ordovician (O 2+3) have low S2 values, ranging from 0.01 to 0.34 and 0.01–5.95 mg HC/g Rock, respectively. The averages of TOC are 1.07% and 0.84% for Є 1 and O 2+3 source rocks, respectively. The equivalent vitrinite reflectance values (VREs) indicate that Є 1 rocks are in a high-over mature stage for oil generation, and O 2+3 rocks are sufficiently mature. Four oil seepages from the Yingshan Formation in the Qingsong quarry of the Aksu area and 34 core samples from Є 1 and O 2+3 rocks in the Kalpin area were analyzed for stable carbon isotopes. Moreover, 4 oil seepages and 16 core samples were analyzed by gas chromatography-mass spectrometry (GC-MS). Compared with O 2+3 rocks, Є 1 rocks are characterized by lower values of Gammacerane/C 30 hopane (G/H), C 28 /(C 27 + C 28 + C 29) 20R ααα sterane (C 28 %), C 29 /(C 27 + C 28 + C 29) 20R ααα sterane (C 29 %), C 26 20S/C 28 20S triaromatic steroids (C 26 /C 28), (C 26 + C 27)/C 28 triaromatic steroids and (C 26 20R + C 27 20S)/C 28 20R triaromatic steroids, and higher values of C 21 /C 23 tricyclic terpane (C 21 /C 23), C 27 /(C 27 + C 28 + C 29) 20R ααα sterane (C 27 %), and C 35 αβ (22R + 22S) homohopane/αβ C 30 -hopane (C 35 H/H). The two sets of source rocks have a "V (C 27 >C 28

Ordovician material from the Platteville Formation (Sandbian) of southern Wisconsin and Big Hill Formation (Katian) of northern Michigan is described that provides novel information about the phylogenetic affinity, taxonomic diversity, and stratigraphic range of the nonbiomineralized taxa Buthograptus, Callithamnopsis, and Chaetocladus. Two new species of Buthograptus, a previously monotypic genus, are erected on the basis of the Platteville Formation material, Buthograptus gundersoni n. sp. and B. meyeri n. sp., and new occurrences of B. laxus are recorded from several localities and two distinct stratigraphic levels within this unit. On the basis of scanning electron microscopic investigation of the material and the fact that each of the three Buthograptus species has a close counterpart in the frond morphology of an extant species of Caulerpa, Buthograptus is interpreted as a member of the green algal order Bryopsidales. New specimens from the Platteville Formation assigned to Callithamnopsis reveal new morphological details for the type species, C. fruticosa (Hall, 1865), aspects of which indicate that the genus belongs to the family Triploporellaceae rather than Seletonellaceae within the green algal order Dasycladales, and Chaetocladus material from the Big Hill Formation includes specimens that are formally assigned to Chaetocladus dubius (Spencer, 1884), a species of dasycladalean alga known previously only from the mid-Silurian of Ontario. [ABSTRACT FROM AUTHOR]

The ichnology of the Middle Ordovician Winnipeg Formation has been analysed based on the study of cores from five wells drilled in southeast Saskatchewan (Canada). Six sedimentary facies, ranging from upper shoreface to lower offshore settings in a shallow‐marine environment, have been characterized. Ichnological attributes are consistent with those in currently proposed models for shallow‐marine wave‐dominated settings, but ichnodiversity is lower than in post‐Palaeozoic settings. Low ichnodiversity in the Winnipeg Formation most likely reflects evolutionary factors rather than environmental controls. Interestingly, low‐energy, distal deposits of the Winnipeg Formation display intense degree of bioturbation, reflecting a well‐developed mixed layer and underscoring the importance of the Great Ordovician Biodiversification Event in terms of sediment mixing. [ABSTRACT FROM AUTHOR]

Sertulaster keslingi new genus new species (Palaeasteridae) and Delicaster hotchkissi new species (Permasteridae) are asteroid echinoderms described, respectively, from the Ordovician and Carboniferous of eastern North America. The new genus and species help to document diversity within taxa of lower rank. S. keslingi is similar to the Early Ordovician EriasterBlake and Guensburg, 2005 but exhibits less differentiation of the skeletal elements from beyond the ambulacral column, that of the so-called extraxial skeleton, whereas the comparatively robust construction of Delicaster hotchkissi clearly departs from that of the type species, D. enigmaticus (Kesling, 1967). Small sample sizes and incomplete exposure of available specimens illustrate ambiguities typically encountered in the study of fossil asteroids. [ABSTRACT FROM AUTHOR]

Early Ordovician A-type granites in the northeastern (NE) Songnen Block NE China were studied to better understand the geodynamic settings in this region. This research presents new zircon U-Pb ages and whole-rock geochemical data for the Early Ordovician granites in the NE Songnen Block. Zircon U-Pb dating indicates that the granite in the Cuibei, Hongxing, and Meixi areas in the NE Songnen Block formed in the Early Ordovician with ages of 471-479 Ma. The granites show geochemical characteristics of high SiO2 and K2O compositions and low FeOT, MgO, CaO, and P2O5 compositions. They belong to a high K calc-alkaline series and display a weak peraluminous feature with A/CNK values of 0.98-1.14. The rocks have a ∑REE composition of 249.98-423.94 ppm, and are enriched in LREE with (La/Yb)N values of 2.87-9.87, and display obvious Eu anomalies (δEu = 0.01-0.29). Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm, and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr + Y + Nb + Ce values (324-795 ppm) and Ga/Al ratios consistent with A-type granites. Based on particular geochemical features, such as high Rb/Nb (7.98-24.19) and Y/Nb (1.07-3.43), the studied A-type granites can be further classified as an A2-type subgroup. This research indicates that the Early Ordovician A-type granites were formed by the partial melting of ancient crust in an extensional setting. Lower Sr/Y and (Ho/Yb)N ratios indicate that plagioclase and amphibole are residual in the source, and garnet is absent, implying that the magma was generated at low levels of pressure. By contrast, the contemporaneous granites in the SE Xing’an Block suggest a subduction-related tectonic setting, and its adakitic property indicates a thickened continental crust. We suggest that the Paleo-Asian Ocean plate between the Xing’an and Songnen blocks subducted northward during the Early Ordovician. Meanwhile, the NE Songnen Block was exposed to a passive continental margin tectonic setting. [ABSTRACT FROM AUTHOR]

An unconventional porous silicified carbonate reservoir was unveiled in the Middle Ordovician fractured limestone within a strike‐slip fault zone in the Tarim Basin, NW China. The silicified carbonates are mainly composed of fine‐ to medium‐crystalline fascicular quartz matrix and coarse crystalline bladed to columnar quartz cement. Fluid inclusion leachate‐residue paired Rb–Sr isotopic dating of the quartz cement yields an isochron age of 167 ± 15 Ma, attesting to a causal link to the Jurassic (Yanshanian) orogeny. Pervasive replacement of matrix quartz and subsequent precipitation of cement quartz through nonisothermal effervescence probably induced by episodic influxes of the hot silica‐ and 87Sr‐rich basinal brines from the neighbouring deeper Manjiaer depression. This study thus signifies the usefulness of using Rb–Sr isotope dating method in constraining the timing of carbonate alteration, enabling to establish the deterministic relationship of basinal fluid evolution with the major tectonic activity. [ABSTRACT FROM AUTHOR]

Altaethyrella tarimensis, a new species of rhynchonellide brachiopod, is described from the late Katian (Late Ordovician) Hadabulaktag Formation in the Kuruktag region of Xinjiang, Northwest China on the northeastern edge of the Tarim Basin. Serial sections of the shell clearly show no dorsal median septum or septalium in the dorsal valve, and no spiralia or atrypide-style crura. Like other species of the genus, A. tarimensis n. sp. exhibits a high degree of intraspecific variation, including variations in shell shape and size, number of ribs in the sulcus at the anterior, and degree of asymmetry. The discovery of Altaethyrella in Tarim has important paleogeographic implications, indicating a close relationship between the Late Ordovician brachiopod faunas of Tarim and those of the Kazakh terranes and North and South China paleoplates, supporting a recently published paleogeographic projection that places Tarim near the Chu-Ili terrane during the Late Ordovician. The abundant large biconvex shells of A. tarimensis n. sp. would have provided a firm substrate for encrusting filter feeders like bryozoans to establish on the Kuruktag Platform. UUID: http://zoobank.org/df8843cd-4db0-48e7-ba03-bf0ce81c4f01 [ABSTRACT FROM AUTHOR]

Computed microtomography (XR-μCT) was used to study the three-dimensional morphology of Palaeoscolex cf. tenensis , a palaeoscolecid worm from the Lower Ordovician Fezouata Lagerstätte (Central Anti-Atlas, Morocco). This method revealed important aspects of its internal anatomy such as a pharynx bearing longitudinal rows of tiny teeth. Tubular structures are interpreted as the fragments of a cylindrical gut tract running from mouth to anus. Energy Dispersive X-ray Analysis (EDX) confirm the primary phosphatic composition of the microplates associated with the cuticle of the worm and suggests that the preservation of soft tissues took place via early bacteria-mediated pyritization followed by strong weathering of Fe-rich aluminosilicates during diagenesis. [ABSTRACT FROM AUTHOR]

Ichnofossils attributed to the ichnogenus Arthrophycus (Hall 1852) have been reported from localities worldwide, including all seven modern-day continents. Arthrophycus is most abundant in Ordovician and Silurian strata and is widely regarded as an ichnostratigraphic indicator of this interval. Occurrences of the ichnogenus from younger strata have been reported, but there is growing consensus that post-Paleozoic records of Arthrophycus are not valid. The oldest confirmed occurrence of Arthrophycus is A. minimus (Mángano et al. 2005a) from the Upper Cambrian of Argentina, South America. The youngest confirmed report is A. parallelus (Brandt et al. 2010) from the Upper Carboniferous (Pennsylvanian) of the Michigan Basin, USA. Paleobiogeographic analysis based on the five most widely accepted ichnogenera confirms the hypothesis that Arthrophycus originated in Gondwana during the Late Cambrian and Early Ordovician, expanded to the northern continents during the Mid-Late Ordovician, reaching its acme during the Silurian, before its decline and extinction by the end of the Paleozoic. [ABSTRACT FROM AUTHOR]

The Volkhovian-Kunda boundary deposits of the Leningrad Region contain two closely related genera, Antigonambonites and Anchigonites. The latter genus was previously known only by valve moulds; here its shell exterior and interior, and ontogeny are described in detail based on the collection of well-preserved disarticulated valves of Anchigonites conulus. Antigonambonites and Anchigonites share similar developmental and morphological features, and ecological strategies including the attachment by cementation by a "pedicle tube" and are thus possibly phylogenetically related. A new diagnosis for the genus Anchigonites and description of A. conulus are provided; other species of Anchigonites are briefly revised. The moulds of outer epithelial cells are described for the first time for the class Strophomenata. [ABSTRACT FROM AUTHOR]

Considerable research has been done on the Ordovician marine fossils from South China, including macrofossils such as brachiopods, graptolites, bivalves, trilobites, some microfossils like conodonts and acritarches. However, radiolarians and ostracods that are also important constituents of the Ordovician marine ecosystem have been paid little attention in this region. In this study, ten radiolarians species belonging to four genera and sixteen ostracods species grouped into nine genera were found from the Hulo Formation at the Hengdu Section of the Jiangshan District, western Zhejiang Province, South China. The fossil-bearing strata belong to the graptolite Pterograptus elegans Zone which indicates the Late Darriwilian Age. This radiolarian fauna is the first record of the Middle Ordovician radiolarian body fossils and also the earliest Ordovician radiolarian fauna reported from South China. The occurrence of Beothuka in this fauna extends the stratigraphic range of the genus to the Upper Darriwilian. Reviews of previous literatures suggest that the diversity of Beothuka was greater during the Early Ordovician, and then declined gradually from the Early Ordovician to the Middle Ordovician before its extinction. The co-occurring ostracod fauna belongs to a shallow-water ecotype. This is contrary to the host lithofacies of the ostracod fauna which represent a deep-water environment. Therefore, these ostacods may have been transported from the shallow-water environment, most likely from the Yangtze carbonate platform. If this conjecture is the truth, then the Jiangshan District was near the shallow-water carbonate platform and received its sediments during the Darriwilian. It is still essential to do more work in the future to better understand the ecology of the Ordovician ostracod fanuas and their role in the sedimentary system of South China. [ABSTRACT FROM AUTHOR]

Graptolites recovered from the organic-rich intervals, previously named the Boas River Formation in the Upper Ordovician succession on Southampton, Akpatok, and southern Baffin islands provide a reliable age assessment for the Upper Ordovician petroleum source rocks in the northern Hudson Bay, Hudson Strait, and Foxe basins. They are characterised by Anticostia lata and Anticostia hudsoni in the lower Red Head Rapids Formation on Southampton Island; Anticostia decipiens and Rectograptus socialis in the lower Foster Bay Formation on Akpatok Island; and Diplacanthograptusspiniferus and Amplexograptus praetypicalis in the lower Amadjuak Formation on southern Baffin Island. These data suggest that the organic-rich intervals in the northern Hudson Bay and Hudson Strait basins can be correlated to the Dicellograptusanceps and Paraorthograptus pacificus zones of the upper Katian, and the horizon in the Foxe Basin to the Diplacanthograptus spiniferus Zone of the lower Katian. The Boas River Formation is not deemed appropriate to use as it occurs as an organic-rich interbed in different stratigraphic units in different basins; therefore, it is suggested to abandon it as a stratigraphic term. [ABSTRACT FROM AUTHOR]

Ordovician epeiric sea carbonates in intracratonic basins of Laurentia are enigmatic due to their unique depositional settings and the absence of modern analogs. Integrated ichnologic and sedimentologic analysis of the Upper Ordovician Stony Mountain Formation in the Williston Basin of Canada allows recognition of neritic-marine, nearshore-marine, open-lagoon, restricted-lagoon, peritidal sand-shoal and peritidal-flat subenvironments. The Cruziana ichnofacies occurs in neritic (between fair-weather and storm wave bases) and nearshore (around fair-weather wave base) marine environments. The depauperate Cruziana ichnofacies is present in open- and restricted-lagoon environments, indicating a shift from fully marine to stressed conditions. In the open lagoon, composite ichnofabrics related to omission surfaces illustrate the low rates of background sedimentation interrupted by event deposition and early cementation, illustrating the Glossifungites and Trypanites ichnofacies. The decreased size of discrete burrows in the restricted lagoon is attributed to reduced oxygenation under stagnation rather than hypersalinity. The peritidal complex includes high-energy sand shoals and low-energy tidal flats. Only monospecific colonization took place sporadically in associated subtidal environments within the peritidal complex deposits. [ABSTRACT FROM AUTHOR]

A bryozoan-dominated fauna that inhabited small caves underneath a carbonate hardground is here described from the Corryville Formation (Upper Ordovician, Katian) exposed near Washington, Mason County, Kentucky, USA. The dominant bryozoan, Stigmatella personata (a trepostome), is found both growing downwards from the cave ceilings and upwards on the exposed hardground surface above. Another trepostome, Monticulipora, is a minor component of the cave fauna. There are few discernible anatomical differences between the bryozoan colonies that grew upwards in presumably well-lit waters and those that grew downwards in the gloomy caves. The pendant, cave-dwelling S. personata in some cases appears to have longer zooecial tubes than its exposed equivalent. The colonies of S. personata are rounded mounds with multiple layers formed by self-overgrowth. The overgrowths in both downward and upward growing forms are marked by thin layers of sediment infilling the upper zooecial chambers in the older portion of the colony. We suggest that biofilms developed on patches of the colony where the zooids had died. Sediment adhered to these surfaces and the colony then overgrew the patches, trapping sediment within the skeleton. The bryozoan zoaria and the carbonate hardground are extensively bored by the cylindrical ichnogenus Trypanites that occasionally contain cylindrical calcite-filled tubes similar to "ghosts" of organic materials. Bioclaustrations are present in some of the bryozoan skeletons. This cave fauna is one of few submarine examples known from the Paleozoic. It supports the hypothesis that early cave-dwelling organisms were little differentiated from their exposed counterparts. [ABSTRACT FROM AUTHOR]

A complete chitinozoan succession through the uppermost Tremadocian to lower Darriwilian (Lower and Middle Ordovician) at Honghuayuan, northern Guizhou Province in South China, was systematically studied and 47 species of 14 genera were identified. Two chitinozoan biodiversity acmes were recognized, which occur in the lower part of the Acrograptus filiformis (uppermost Hunghuayuan Formation) and middle part of the Azygograptus suecicus (middle member of the Meitan Formation) graptolite biozones. In the upper Dapingian and lower Darriwilian (uppermost part of the Meitan Formation), chitinozoan diversity was relatively high after a less conspicuous peak in the upper Dapingian. Comparisons between diversity trends of chitinozoans, acritarchs and brachiopods, and the environmental changes revealed both similarities and differences. In the Floian, the chitinozoan biodiversity curve at Honghuayuan shows good correlation with sea-level changes. The group temporarily disappeared when the sea level was at the highest, then reappeared and reached a biodiversity acme when sea level was low. Furthermore, a large organic carbon isotope excursion is coincident with the absence of chitinozoans and a highstand period after the sea-level rise in the lower and middle Floian. Diversity curves show fewer connections with the sea-level and organic C-isotope undulations during the Dapingian and early Darriwilian. New data suggest that the environmental changes played a significant role in the early stage of Ordovician chitinozoan radiation, roughly corresponding to the Floian at the Honghuayuan section. In the Dapingian and early Darriwilian, the intrinsic factors seem to have played a more important role in shaping biodiversity patterns of chitinozoans in South China. [ABSTRACT FROM AUTHOR]

Mass extinctions documented by the fossil record provide critical benchmarks for assessing changes through time in biodiversity and ecology. Efforts to compare biotic crises of the past and present, however, encounter difficulty because taxonomic and ecological changes are decoupled, and although various metrics exist for describing taxonomic turnover, no methods have yet been proposed to quantify the ecological impacts of extinction events. To address this issue, we apply a network-based approach to exploring the evolution of marine animal communities over the Phanerozoic Eon. Network analysis of fossil co-occurrence data enables us to identify nonrandom associations of interrelated paleocommunities. These associations, or evolutionary paleocommunities, dominated total diversity during successive intervals of relative community stasis. Community turnover occurred largely during mass extinctions and radiations, when ecological reorganization resulted in the decline of one association and the rise of another. Altogether, we identify five evolutionary paleocommunities at the generic and familial levels in addition to three ordinal associations that correspond to Sepkoski's Cambrian, Paleozoic, and Modern evolutionary faunas. In this context, we quantify magnitudes of ecological change by measuring shifts in the representation of evolutionary paleocommunities over geologic time. Our work shows that the Great Ordovician Biodiversification Event had the largest effect on ecology, followed in descending order by the Permian-Triassic, Cretaceous-Paleogene, Devonian, and Triassic-Jurassic mass extinctions. Despite its taxonomic severity, the Ordovician extinction did not strongly affect co-occurrences of taxa, affirming its limited ecological impact. Network paleoecology offers promising approaches to exploring ecological consequences of extinctions and radiations. [ABSTRACT FROM AUTHOR]

Reports of Ordovician conodonts from the Arabian region of the Gondwanan margin are extremely rare. Here we provide a description of the apparatus of two new conodont genera and species,Aldridgeognathus mannikiandOmanognathus daiqaensis, based on discrete elements recovered from the Am5 Member of the Amdeh Formation, Darriwilian, Ordovician of the Sultanate of Oman. The apparatuses contain 17 and 15 elements, respectively, and both possess three pairs of P elements. The apparatus structure ofOmanognathusis similar to the bedding plane assemblage-defined genusNotiodella(=Icriodella) but differs in that as yet only 15 elements rather than 17 have been identified.Aldridgeognathushas similar P elements to the early Silurian apparatusPranognathusbut differs in the possession of a geniculate M element and aBaltoniodus-like S element array.Aldridgeognathusdoes not easily fit with either the 17-elementNotiodella(Icriodella) or the 19-elementPromissumtemplates and suggests that there may be other 17-element Ordovician apparatus templates with very similar or duplicated elements in the P element positions. A cladistic analysis based on the data set of Donoghue (2008) confirms that both new genera should be classified with the Balognathidae and suggests that they, along with another newly described three P element bearing genusArianagnathus, are more derived thanBaltioniodusandPrioniodusbut ancestral toIcriodella,Sagittodontina,PromissumandNotiodella. The exact position ofAldridgeognathusis not well resolved in respect to the newly describedArianagnathusorOmanognathus. These new taxa add little to attempts to correlate the Arabian Peninsula with other palaeogeographic regions, but may prove useful for future correlation within the region and provide data to test the hypothesis of Dzik (2015) that the origins for prioniodontid conodonts lie in high latitudes during the Ordovician. http://zoobank.org/urn:lsid:zoobank.org:pub:84C8267D-76E8-4DD3-92F3-0B72CA976DEC [ABSTRACT FROM AUTHOR]

Abstract: The Middle Ordovician conodont genera that are suitable for palaeoenvironmental interpretations from the epicontinental Baltoscandian platform have been identified and evaluated to establish and describe conodont biofacies and their relationship to global cooling. The construction of biofacies was based on multivariate statistical analyses of more than 375 700 conodont specimens from 520 samples and 21 localities across Baltica. Three distinct, recurrent and laterally extensive conodont biofacies existed across the Baltoscandian platform of the Baltica continent during the Dapingian and early to middle Darriwilian stages (Middle Ordovician). A relatively shallow water conodont assemblage named the Baltoniodus–Microzarkodina Biofacies characterized the inner shelf localities in central Sweden, Estonia, Russia and Ukraine. In the distal shelf areas, patterns are more complex. Here, genera of the Periodon Biofacies characterized the shelf margin areas of the Scandinavian Caledonides facing the relatively warm Iapetus Ocean towards the north, whereas the Protopanderodus Biofacies dominated the distal shelf areas facing the cooler Tornquist Sea towards the south‐west. Although these three main biofacies continued to dominate during the succeeding Darriwilian stage, distinct changes in the distribution of biofacies took place during the transition from the Dapingian Stage to the Darriwilian. We argue that the biofacies change was triggered by a regressive event related to early Darriwilian cooling, and that the palaeoclimatological changes influenced the Baltic conodont faunas near the Tornquist Sea margin before those of the Iapetus margin (early vs middle Darriwilian). [ABSTRACT FROM AUTHOR]

With increasingly high comprehensive mining intensity to the coal resources and wider mining width of the mining area, the mines of Chenghe No.2 mineral are getting deeper and deeper and the hazard from the high pressure water of Ordovician limestone of #5 coal bed bottom is getting increasingly intense, which will seriously influence safety production of the mines. Therefore, how to liberate the under draught coal reserves of #5 water body is a difficult problem as well as the key issue to ensure safety production of the mines. As for this, the first author will combine with the hydrogeological condition of Chenghe No.2 mineral in this article, and adopt standardized water bursting coefficient method to evaluate the water insulation capability of Taiyuan formation #5 coal floor upon comprehensive analysis on influencing factors of floor water inrush, to consider whether to divide #5 coal floor under waterdiversion failing zone thickness into different compensated mining areas, having predicted water inrush probability of the mining area in the future, and to release the coal reserves threatened by Ordovician water disaster. The result shows: (1) Among the factors that influence #5 coal floor water inrush of Chenghe No.2 mineral, head pressure of the aquifer is motive power of water inrush, the floor strata lithology and its combination feature are safety barrier for confined water extraction, and geological structure is in most cases the channel of floor water inrush; in accordance with the latest stipulations on mine water prevention and control and design specifications on coal mine water prevention, the first author takes 0.06MPa/m and 0.1MPa/ m as boundary conditions of critical water inrush coefficient, divides #5 coal floor water-resisting layer into compensated mining extremely dangerous zone, dangerous zone and exploitable zone; (2) As to areas that mining above the pressured water are inapplicable in consideration of the coal floor water-diversion failing zone, latest water bursting coefficient formula can be adopted to realize safe compensated mining, which has reduced danger of floor water inrush, and satisfied the requirements of safe compensated mining of this mining area; (3) Without considering condition of the water-diversion failing zone, it can liberate compressed coal reserves of #5 coal floor that are threatened by Ordovician limestone water disaster and enhance the recovery ratio of coal resources; (4) Based on the evaluation results of floor water inrush danger, the author has proposed major water disasters to the coal floor and prevention countermeasures, which has provided valuable reference for safety compensated coal mining above seam floor pressure-bearing water body of Chenghe minerals and even Weibei coalfield, brought tremendous social and economic benefits, is of practical significance for realization of green coal mining, and will drive local economic development, thus worth being generalized and applied. [ABSTRACT FROM AUTHOR]

The extent to which biological diversity affects rates of diversification is central to understanding macroevolutionary dynamics, yet no consensus has emerged on the importance of diversity-dependence of evolutionary rates. Here,we analyse the species-level fossil record of early Palaeozoic graptoloids, documented with high temporal resolution, to test directly whether rates of diversification were influenced by levels of standing diversity within this major clade of marine zooplankton. To circumvent the statistical regressionto- the-mean artefact, whereby higher- and lower-than-average values of diversity tend to be followed by negative and positive diversification rates, we construct a non-parametric, empirically scaled, diversity-independent null model by randomizing the observed diversification rates with respect to time. Comparing observed correlations between diversity and diversification rate to those expected from this diversity-independent model, we find evidence for negative diversity-dependence, accounting for up to 12% of the variance in diversification rate, with maximal correlation at a temporal lag of approximately 1 Myr. Diversity-dependence persists throughout the Ordovician and Silurian, despite a major increase in the strength and frequency of extinction and speciation pulses in the Silurian. By contrast to some previous work, we find that diversity-dependence affects rates of speciation and extinction nearly equally on average, although subtle differences emerge when we compare the Ordovician and Silurian. [ABSTRACT FROM AUTHOR]

Profound changes in environmental conditions, particularly atmospheric oxygen levels, are thought to be important drivers of several major biotic events (e.g. mass extinctions and diversifications). The early Paleozoic represents a key interval in the oxygenation of the ocean–atmosphere system and evolution of the biosphere. Global proxies (e.g. carbon ( δ 13 C) and sulfur ( δ 34 S) isotopes) are used to diagnose potential changes in oxygenation and infer causes of environmental change and biotic turnover. The Cambrian–Ordovician contains several trilobite extinctions (some are apparently local, but others are globally correlative) that are attributed to anoxia based on coeval positive δ 13 C and δ 34 S excursions. These extinction and excursion events have yet to be coupled with more recently developed proxies thought to be more reflective of local redox conditions in the water column (e.g. I/Ca) to confirm whether these extinctions were associated with oxygen crises over a regional or global scale. Here we examine an Early Ordovician (Tremadocian Stage) extinction event previously interpreted to reflect a continuation of recurrent early Paleozoic anoxic events that expanded into nearshore environments. δ 13 C, δ 34 S, and I/Ca trends were measured from three sections in the Great Basin region to test whether I/Ca trends support the notion that anoxia was locally present in the water column along the Laurentian margin. Evidence for anoxia is based on coincident, but not always synchronous, positive δ 13 C and δ 34 S excursions (mainly from carbonate-associated sulfate and less so from pyrite data), a 30% extinction of standing generic diversity, and near-zero I/Ca values. Although evidence for local water column anoxia from the I/Ca proxy broadly agrees with intervals of global anoxia inferred from δ 13 C and δ 34 S trends, a more complex picture is evident where spatially and temporally variable local trends are superimposed on time-averaged global trends. Stratigraphic sections from the distal and deeper part of the basin (Shingle Pass and Meiklejohn Peak) preserve synchronous global ( δ 13 C and δ 34 S) and water column (I/Ca) evidence for anoxia, but not at the more proximal section (Ibex, UT). Although geochemical and paleontological evidence point toward anoxia as the driver of this Early Ordovician extinction event, differences between I/Ca and δ 13 C– δ 34 S signals suggest regional variation in the timing, extent, and persistence of anoxia. [ABSTRACT FROM AUTHOR]

The Middle to Late Ordovician was a time of profound biotic diversification, paleoecological change, and major climate shifts. Yet studies examining speciation mechanisms and drivers of dispersal are lacking. In this study, we use Bayesian phylogenetics and maximum likelihood analyses in the R package BioGeoBEARS to reanalyze ten published data matrices of brachiopods and trilobites and produce time-calibrated species-level phylogenetic hypotheses with estimated biogeographic histories. Recovered speciation and biogeographic patterns were examined within four time slices to test for changes in speciation type across major tectonic and paleoclimatic events. Statistical model comparison showed that biogeographic models that incorporate long-distance founder-event speciation best fit the data for most clades, which indicates that this speciation type, along with vicariance and traditional dispersal, were important for Paleozoic benthic invertebrates. Speciation by dispersal was common throughout the study interval, but notably elevated during times of climate change. Vicariance events occurred synchronously among brachiopod and trilobite lineages, indicating that tectonic, climate, and ocean processes affected benthic and planktotrophic larvae similarly. Middle Ordovician inter-oceanic dispersal in trilobite lineages was influenced by surface currents along with volcanic island arcs acting as “stepping stones” between areas, indicating most trilobite species may have had a planktic protaspid stage. These factors also influenced brachiopod dispersal across oceanic basins among Laurentia, Avalonia, and Baltica. These results indicate that gyre spin-up and intensification of surface currents were important dispersal mechanisms during this time. Within Laurentia, surface currents, hurricane tracks, and upwelling zones controlled dispersal among basins. Increased speciation during the Middle Ordovician provides support for climatic facilitators for diversification during the Great Ordovician Biodiversification Event. Similarly, increased speciation in Laurentian brachiopod lineages during the Hirnantian indicates that some taxa experienced speciation in relation to major climate changes. Overall, this study demonstrates the substantial power and potential for likelihood-based methods for elucidating biotic patterns during the history of life. [ABSTRACT FROM AUTHOR]

Well-preserved miospore assemblages are recorded from the Late Ordovician (Katian–Hirnantian) Ghelli Formation in the Pelmis Gorge, located in the Alborz Mountain Range, Northeastern Iran. The palynomorphs were extracted from siliciclastic deposits that are accurately dated using marine palynomorphs (acritarchs and chitinozoans). The spore assemblages consist of 14 genera and 28 species (26 cryptospores and 2 trilete spore species). Six new cryptospore species are described: Rimosotetras punctata n.sp., Rimosotetras granulata n.sp., Dyadospora asymmetrica n.sp., Dyadospora verrucata n.sp., Segestrespora iranense n.sp., and Imperfectotriletes persianense n.sp. The study furthers knowledge of the development of the vegetative cover during the Late Ordovician. Various and abundant cryptospores in the Late Ordovician (Katian–Hirnantian) Ghelli Formation are probably related to the augmentation of land-derived sediments either during the global sea-level fall linked to the Late Ordovician glaciation or adaptation of the primitive land plants in a wide range of climatic conditions. These miospore taxa were produced by the earliest primitive land plants, which probably grew close to the shoreline and were washed in from adjacent areas, producing a high volume of miospores. The associated marine palynomorphs consist of acritarchs (13 genera and 18 species), chitinozoans (9 genera and 10 species), prasinophycean algae, scolecodonts, and graptolite remains, which are not discussed in detail herein. The established chitinozoan biozones of this part of the Palaeozoic sequence are the Armoricochitina nigerica Biozone, the Ancyrochitina merga Biozone, the Tanuchitina elongata Biozone, and the Spinachitina oulebsiri Biozone, suggesting a Late Ordovician age (Katian–Hirnantian). These chitinozoan biozones are widely evidenced only in the peri-Gondwanan Domain, indicating that the study area was part of this palaeo-continent in the Late Ordovician. [ABSTRACT FROM AUTHOR]

Scolecodonts provide fossil evidence of the evolution and diversification of jaw-bearing polychaetes from the latest Cambrian onwards. However, their record before the Darriwilian (Middle Ordovician) is scarce worldwide, which limits our understanding of key evolutionary events. One such event is the emergence of taxa possessing the asymmetrical labidognath-type jaw apparatus architecture, which became common in the Middle Ordovician and is often dominant throughout the Palaeozoic. Here, we document a small collection of Dapingian scolecodonts from the Capillas section, Sierras Subandinas, north-western Argentina. The isolated elements recovered allowed us to reconstruct the distinctive jaw apparatus, and to introduce a new taxon, Andiprion paxtonae gen. et sp. nov. The maxillary apparatus of Andiprion is intermediate between the symmetrognath type of the Early Ordovician Kadriorgaspis and the labidognath type that is present in polychaetaspids and related taxa. The apparatus architecture of Andiprion corresponds best to the labidognath type, but the morphology of the individual jaws suggests that it may be the most primitive representative of this lineage currently known. We propose that Andiprion-like forms were ancestral to polychaetaspids, polychaeturids and ramphoprionids. The Capillas collection provides supporting evidence for the evolutionary homology of the 'basal plate' and the left first maxilla. Thus the labidognath-type asymmetry, with an unpaired left maxilla III, developed as a result of gradual reduction in size of the first right jaw ('basal plate') in front of the carriers, instead of loss or fusion of anterior maxillae. [ABSTRACT FROM AUTHOR]

Since 1986, samples with a total mass of more than 14,000 kg, mainly from three key sections in western Hunan, South China, have been processed for conodonts. Previous work mainly focused on biostratigraphy, but the taxonomy has been performed only on the faunas of the middle Cambrian. Described herein are conodonts of the upper Cambrian (Furongian Series) through lowermost Ordovician from Hunan, South China. Conodonts of the middle Cambrian are redescribed, based on material that has been recovered for more than three decades. The fauna consists of 82 species belonging to 36 genera. Newly established genera are Lugnathus n. gen., Miaognathus n. gen., Millerodontus n. gen., Tujiagnathus n. gen., Wangcunella n. gen. and Wangcunognathus n. gen. New species are Coelocerodontus hunanensis n. sp., Furnishina wangcunensis n. sp., Laiwugnathus hunanensis n. sp., Laiwugnathus transitans n. sp., Lugnathus hunanensis n. gen. n. sp., Miaognathus multicostatus n. gen. n. sp., Millerodontus intermedius n. gen. n. sp., Prosagittodontus compressus n. sp., Tujiagnathus gracilis n. gen. n. sp., Wangcunella conicus n. gen. n. sp., Wangcunognathus elegans n. gen. n. sp., Westergaardodina dimorpha n. sp., Westergaardodina gigantea n. sp., and Westergaardodina sola n. sp. The taxonomy of some conodont genera is revised. In the light of histological investigation, genera are assigned to euconodonts, paraconodonts, or protoconodonts. The 13 conodont zones previously proposed in the middle Cambrian through lowermost Ordovician remain the same, but taxa within these conodont zones are documented more clearly because of the revised taxonomy proposed herein. [ABSTRACT FROM AUTHOR]

Despite a plethora of exceptionally preserved trilobites, trilobite reproduction has remained a mystery. No previously described trilobite has unambiguous eggs or genitalia preserved. This study reports the first occurrence of in situ preserved eggs belonging to Triarthrus eatoni (Hall, 1838) trilobites from the Lorraine Group in upstate New York, USA. Like other exceptionally preserved trilobites from the Lorraine Group, the complete exoskeletons are replaced with pyrite. The eggs are spherical to elliptical in shape, nearly 200 µm in size, and are clustered in the genal area of the cephalon. The fact that the eggs are smaller than the earliest-known trilobite ontogenetic (protaspis) stage suggests that trilobites may have had an unmineralized preliminary stage in their ontogeny, and that the protaspis shield formed only after hatching. The eggs are only visible ventrally with no dorsal brood pouch or recognized sexual dimorphism. The location of the eggs is consistent with where modern female horseshoe crabs release their unfertilized eggs from the ovarian network within their head. Trilobites likely released their gametes (eggs and sperm) through a genital pore of as-yet unknown location (likely near the posterior boundary of the head). If the T. eatoni reproductive biology is representative of other trilobites, they spawned with external fertilization, possibly the ancestral mode of reproduction for early arthropods. Because pyritization preferentially preserves the external rather than internal features of fossils, it is suggested that there is likely a bias in the fossil record toward the preservation of arthropods that brood eggs externally: arthropods that brood their eggs internally are unlikely to preserve any evidence of their mode of reproduction. [ABSTRACT FROM AUTHOR]

Summary The Late Ordovician (Hirnantian, approximately 445 million years ago) extinction event was among the largest known, with 85% species loss [ 1 ]. Post-extinction survival faunas are invariably low diversity, especially benthic communities [ 2 ], but ecological structure was restored relatively rapidly [ 1 ]. This pattern, however, reflects organisms with robust skeletons, as only one exceptionally preserved Hirnantian fossil biota was previously known [ 3, 4 ]; in particular, almost no Hirnantian sponges have been recorded. Our study reveals an extraordinarily diverse, sponge-dominated community thriving immediately after the Hirnantian extinction in Zhejiang, South China. Several contemporaneous sites preserve a total diversity of over 75 sponge species, many with preserved soft tissues, in pronounced contrast to normal survival and early recovery faunas. This diversity is unprecedented for any Hirnantian fossil group, and the fauna provides a unique window into a post-extinction ecosystem. The sponges are often large and structurally complex and represent numerous different lineages that survived the extinction. Layers with abundant sponge remains were deposited after other mass extinctions [ 5, 6 ], suggesting a general pattern of sponge abundance during collapse of Phanerozoic marine ecosystems. It is possible that the conditions of ecological collapse increase the particulate food sources for sponges, while they themselves are relatively unaffected by the crises. Furthermore, the abundance of sponges in the Hirnantian sequence of South China may have aided post-extinction ecosystem recovery by stabilizing the sediment surface, allowing sessile suspension feeders such as brachiopods, corals, and bryozoans to recover rapidly. [ABSTRACT FROM AUTHOR]

Although putative corals of uncertain affinities occur in the early Cambrian, the earliest definite tabulate corals have not been described prior to the Early Ordovician in North America. This paper reports a new finding of a tabulate-like coralomorph forming part of biostratigraphically well-constrained reef mounds in the latest Cambrian–Early Ordovician La Silla Formation in the Argentine Precordillera. The oldest record of the coralomorph genus Amsassia is reported and a new species, A. argentina, is erected. The discovery of this genus in the lowermost Ordovician modifies the previously proposed paleogeographic distribution and patterns of origination and migration routes of this coral-like organism. Amsassia argentina n. sp. constitutes a main framework builder together with a complex microbial consortium. This oldest occurrence of Amsassia as a reef builder represents a new record of a skeletal organism in the gap of metazoan reef constructors after the demise of archaeocyaths in the late early Cambrian. [ABSTRACT FROM PUBLISHER]

The re-study of species previously attributed to the genusNanorthisfrom the Tremadocian of north-western Argentina has led to the recognition of the new generaGondwanorthis(type speciesNanorthis calderensisBenedetto), to which the Iranian speciesNanorthis bastamensisGhobadi Pour, Kebriaee-Zadeh & Popov is also referred, andLampazarorthis(type speciesEoorthis bifurcataHarrington), which includesNanorthis brachymyariaBenedetto andLampazarorthis alatasp.nov.New extensive collections from the Cordillera Oriental support reassignment of the upper Tremadocian speciesNanorthis purmamarcaensisto the genusTarfaya. The speciesNanorthis carinataLaurie, from Tasmania, is reassigned here toTarfaya. According to the present taxonomic revision,Nanorthisis not cosmopolitan but is a pan-tropical genus, confined to Laurentia, the Laurentian-derived Precordillera terrane, and probably to Baltica, Siberia and Kazakhstanian terranes, whereasGondwanorthisandTarfayaare Gondwanan and peri-Gondwanan endemic taxa. Cladistic analysis of early orthoids, plectorthoids and dalmanelloids, including those recorded from mid to high latitude Gondwana successions, portraysGondwanorthisandLampazarorthisas a sister group basal to the tarfayid + heterorthid clade, whereas the South American and North AfricanIncorthisappears as a basal member of this clade. Morphological and stratigraphical evidence provided in this study, along with the results of the cladistic analysis, supports the view that heterorthids could have arisen from the tarfayids by the end of Floian. The enlargement and incipient bilobation of the cardinal process inTarfaya grandisleaves this species as a potential ancestor ofTissintia, which occurs in Darriwilian beds of the Central Andean Basin (Bolivia), but could have been present in this basin since the late Floian. We speculate that punctae in the Heterorthidae evolved independently from aTarfaya-like ancestor, and that the transition from an impunctate to a punctate shell may have occurred repeatedly through rhynchonelliform evolution. http://zoobank.org/urn:lsid:zoobank.org:pub:FFE818F6-FA92-4B26-AE76-077617C3D9EA [ABSTRACT FROM AUTHOR]

Middle Ordovician (Darriwilian) monothalamous agglutinated foraminifers are described for the first time from strata of the Lashkarak Formation of the Simeh-Kuh section, AlborzMountains, northern Iran. One new genus Damghanites Nestell and Ghobadi Pour with the type species D. lashkarakensis, and three new species Amphitremoida simehkuhensis, Sorosphaera iranensis and S. darriwiliensis are described. Analysis of the foraminiferal wall of some of these species has revealed the presence of quartz, feldspar, products of feldspar degradation and rare grains of anatase, and also the presence of iron. Conodonts fromthe lower part of the Lashkarak Formation indicate an age within the interval of the Lenodus variabilis to Eoplacognathus? pseudoplanus zones of the lower Darriwilian (Middle Ordovician). [ABSTRACT FROM AUTHOR]

Exceptionally preserved fossils yield crucial information about the evolution of Life on Earth. The Fezouata Biota from the Lower Ordovician of Morocco is a Konservat-Lagerstätte of major importance, and it is today considered as an ‘Ordovician Burgess Shale.’ This biota was discovered only some 15 years ago, but geological studies of the area date back to the beginning of the 20th century. Pioneering geological investigations lead to the discovery of Ordovician strata in the Anti-Atlas (1929) and ultimately resulted in their formal subdivision into four main stratigraphic units (1942). In the Agdz area, the presence of fossiliferous Tremadocian (Lower Ordovician) strata was suspected as early as 1939, but only definitively confirmed in 1955. In the 1960s–1990s, Jacques Destombes provided the first detailed biostratigraphic framework for the Lower Ordovician of the Anti-Atlas, and collected thousands of fossils that were subsequently described in a series of monographs. In the early 2000s, exceptionally preserved fossils were discovered in the Fezouata Shale (Tremadocian–late Floian) in the central Anti-Atlas by Mohamed ‘Ou Saïd’ Ben Moula. This biota, now known as the Fezouata Biota, is of utmost importance, for it demonstrates the extent in the fossil record of non-biomineralising animals typical of the ‘Cambrian Explosion’ into the Ordovician, during the ‘Great Ordovician Biodiversification.’ Although most components are still in need of formal descriptions, a fairly good picture of the composition and organisation of this biota, and how it contributes to our understanding of the early evolution of metazoan communities, can now be depicted. Moreover, recent studies have substantially clarified the biostratigraphical and palaeoenvironmental context of the Fezouata Shale, and are now being followed up by detailed investigations of the taphonomy, geochemistry and micropalaeontology of this unique Konservat-Lagerstätte . These efforts will soon greatly benefit from the recovery of fresh, unweathered samples from drill cores. [ABSTRACT FROM AUTHOR]

The hill range of Vaivara Sinimäed in northeast Estonia consists of several narrow east- to northeast-trending glaciotectonic fold structures. The folds include tilted (dips 4-75°) Middle Ordovician (early Darriwilian) layered carbonate strata that were studied by mineralogical, palaeomagnetic, and rock magnetic methods in order to specify the post-sedimentational history of the area and to obtain a better control over the palaeogeographic position of Baltica during the Ordovician. Mineralogical studies revealed that (titano)magnetite, hematite, and goethite are carriers of magnetization. Based on data from 5 sites that positively passed a DC tilt test, a south-easterly downward directed component A ( Dref = 154.6°± 15.3°, Iref = 60.9°± 9.7°) was identified. The component is carried by (titano)magnetite, dates to the Middle Ordovician ( Plat = 17.9°, Plon = 47.3°, K = 46.7, A95 = 11.3°), and places Baltica at mid-southerly latitudes. Observations suggest that in sites that do not pass the tilt test, the glaciotectonic event has caused some rotation of blocks around their vertical axis. [ABSTRACT FROM AUTHOR]

The Lower Ordovician Shirgesht Formation in central Iran is composed of siliciclastic and carbonate rocks deposited in diverse coastal and marine shelfal environments (tidal flat, lagoon, shoreface, offshore-shelf and carbonate ramp). Five facies associations contain diverse ichnofossil assemblages that show distinct proximal to distal trends formed in a wide range of physical-chemical conditions. The ethological groups of trace fossils in the Shirgesht Formation reflect a gradient of depositional stress conditions across a wave-influenced shoreline and shelf. Deposits of wave-influenced environments make up a significant component of the geological record of shallow marine settings, and the ability to determine paleoenvironments in detail in such successions is critical for reconstruction of depositional histories and sequence-stratigraphic interpretation. The Cruziana ichnofacies of the study shows highly diverse suites that record the establishment of a benthic community under stable conditions and a long-term colonization window. The Skolithos ichnofacies recognized is a low diversity opportunistic ichnocommunity suite that resulted from colonization after tempestite deposition in a stressed environment. The strata record an onshore to offshore replacement of the Cruziana ichnofacies (with abundant feeding traces of deposit-feeders) by the Skolithos ichnofacies (dominated by suspension-feeders and predators). A transitional zone between the two ichnofacies coincides with the offshore-transition/distal lower-surface deposits. The distribution of ichnofacies, the diversity and range of ethological characteristics reflected by the ichnogenera, and the wide range of wave-dominated coastal facies demonstrate the potential to use individual trace fossils and ichnofacies for significantly refined palaeoenvironmental analysis of wave-dominated coastal settings, particularly in Ordovician successions. [ABSTRACT FROM AUTHOR]

New high-resolution chemostratigraphy, in combination with updated biostratigraphy, refines the chronostratigraphic resolution of the nearly 2 km thick Ordovician section below Anticosti Island. A total of 1414 horizons, spaced at 1.0-1.5 m intervals, were sampled from the New Associated Consolidated Paper (NACP) drill core and analyzed for major and trace elemental composition by portable X-ray fluorescence analyzer (pXRF). Select micrite and calcareous shale powders were then analyzed for δ13Ccarb (number of samples, N = 364) and 87Sr/86Sr ( N = 25). Our results indicate a Floian to early Darriwilian (F3-Dw1) age for the Romaine Formation, a middle Darriwilian to Sandbian (Dw2-Sa1) age for the Mingan Formation, a lower to mid-Katian (Ka1-Ka2) age for the Macasty Formation, an upper Katian (Ka3) age for the lower Vauréal Formation, an uppermost Katian (Ka4) age for the upper Vauréal, and a Hirnantian (H1) age for the Ellis Bay Formation. This integrated chemostratigraphic and biostratigraphic synthesis establishes the position of numerous unconformities, the duration of the intervening depositional sequences, and rates of sedimentation. [ABSTRACT FROM AUTHOR]

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An enigmatic clonal organism from the earliest Floian (Arenig) Fenxiang Formation at Tianjialing in Hubei Province, China and here named Crinisdendrum sinicum gen. et sp. nov., shows a puzzling combination of anatomical characters. Lateral colony branches that originate from tubular stolons are built of C-shaped serial oblique units resembling fuselli and merging along a zig-zagged suture, a set of features generally believed to be unique to pterobranch hemichordates. At least most branches taper near their tips and are closed in a manner resembling the termination of thecae previously reported in the extant pterobranch Rhabdopleura normani. The main drawback of the pterobranch model is that previous observations of terminating thecae in R. normani have neither been confirmed by more recent zoological studies nor explained in functional and developmental terms. Pyritized Crinisdendrum specimens preserved in shale were scanned using X-ray microtomography, enabling restoration of early stages of colony development (astogeny). Pyritic internal moulds of probable thecae, showing their interiors in negative relief, and phosphatized walls of thecae overgrown by black corals were recovered chemically from samples of calcareous intercalations in the Fenxiang Formation. Both sets of specimens exhibit a thread-like cylindrical structure resembling a stolon inside the theca and located below the zigzagged suture. A similar organization of branches also characterizes the feathery colonies of Webbyites from the Early Ordovician Klabava Formation of Bohemia, although these colonies are known in less detail. A new family, Crinisdendridae is proposed to encompass these two genera. Further testing of the hypothesis of a pterobranch affinity for these 470-million-year-old organisms will require a better understanding of the anatomy and growth of extant clonal hemichordates. [ABSTRACT FROM AUTHOR]

Calcified cyanobacteria and associated microfossils were examined in 8500 thin sections of Ordovician core samples from 64 wells in carbonate platforms of the Tarim Basin, Xinjiang Province, Northwest China. They include 32 species (including three uncertain species) belonging to 20 genera, most of which are from the Middle and Upper Ordovician. Two new genera and species,Acuasiphonoria ordovicagen. et sp. nov. andGomphosiphon xinjiangensisgen. et sp. nov., and two new species,Proaulopora pachydermaticasp. nov. andRothpletzella longitasp. nov., are described. Calcified cyanobacteria includeGirvanella,Subtifloria,Razumovskia,Acuasiphonoriagen. nov.,Hedstroemia,Cayeuxia,Bija,Apophoretella,Ortonella,ZonotrichitesandBevocastria. Probable calcified cyanobacteria includeProaulopora,PhacelophytonandGomphosiphongen. nov. Calcified Microproblematica includeRenalcis,Izhella,Epiphyton,Wetheredella,RothpletzellaandGarwoodia. This assemblage is diverse in comparison with similar Ordovician fossils reported from other areas, and includes six genera and 14 species recorded from the Ordovician for the first time. Calcified cyanobacteria and their associated microfossils are more diverse in the Middle and Late Ordovician than was previously known. [ABSTRACT FROM AUTHOR]

Coralla of the solitary coral Talfania calicula gen. et sp. nov. from the Upper Ordovician (Ashgill Series; Katian Stage) of Llanddowror, South Wales, UK, are often coiled around crinoid columnals, suggesting a premortem association between some of the corals and living crinoids. Irregularities within the deepest part of the open calice imply infestation of T. calicula by parasitic worms. Talfania calicula is distinguished from contemporaneous rugose corals by its lack of septa within the calice and its systematic position within Zoantharia is unresolved. Pitted calical grooves are interpreted as attachment scars of desmocytes connecting the soft tissues to the exoskeleton. Coral and crinoid remains in the assemblage are bored by postmortem microendoliths. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article describes a log-stratigraphical breakdown of the Middle Ordovician to lower Silurian shale-dominated succession in Scandinavia. Topics covered include the thickness of the Lower Palaeozoic shales, the transition from passive margin to foreland basin and the subdivision of the Cyrtograptus shale into log zones. Also mentioned is the difference in sedimentation between the areas from the onset of the Cyrtograptus shale deposition.

The conodont species Caenodontus serrulatus Behnken is a rare coniform element first described in 1975 from Guadalupian strata exposed in theGuadalupe andDelawareMountains ofWest Texas. Because it is rare, coniform, and occurs long after most coniform elements supposedly disappeared, it has been hauntingly mysterious. Based on new material containing a varied assemblage of coniform elements recovered from an outcrop of the Hegler Limestone (Guadalupian) in the Patterson Hills, West Texas, it is proposed that Caenodontus is comprised of a 6-7membrate coniform apparatus and that this apparatus is very similar to the one proposed for the genus Ansella from the Ordovician. [ABSTRACT FROM AUTHOR]

Seven hydrocarbon reservoirs have been discovered to date in the Upper Ordovician of the Tazhong Area, a region in which hydrocarbon phase distribution is complex. In the present study, the genesis and controlling factors of the hydrocarbons with complex phase in the Tazhong Area were investigated on the basis of the geological and geochemical conditions required for the formation and distribution of hydrocarbon reservoirs, integrated with the source rock geochemistry, natural gas and oil properties, and oil and gas reservoir fluid tests PVT (i.e., pressure, volume, and temperature tests). The results indicate that hydrocarbon reservoir types in the Upper Ordovician of the Tazhong Area transition from unsaturated to saturated condensate-gas reservoirs from west to east and from condensate-gas reservoirs to unsaturated-oil reservoirs from north to south. The crude oil in the region originated primarily from the mixing of Lower-Middle Cambrian and Middle-Upper Ordovician source rocks, while the natural gas was sourced primarily from the cracking gas of Lower-Middle Cambrian crude oil. This hydrocarbon-phase distribution was controlled primarily by temperature and pressure and has been affected by multiple periods of hydrocarbon accumulation and alteration. The high-quality Lower-Middle Cambrian reservoir-cap assemblage may be an important target for future exploration of natural gas in the Tazhong Area. [ABSTRACT FROM AUTHOR]

All known occurrences of crinoids in the Ordovician of France (Armorican Massif, Montagne Noire, Corbières and Pyrénées) are reviewed and replaced stratigraphically. Fully articulated crinoids are described for the first time in the Darriwilian (Middle Ordovician) of the Armorican Massif. The disparid crinoid Heviacrinus melendezi is reported from the middle and late Darriwilian ( artus and teretiusculus zones) of both Brittany and Normandy, which extends both its geographic distribution and its temporal range. In addition, a new species of Heviacrinus , H. tromelini is described from the late Darriwilian ( teretiusculus zone) of both Brittany and Normandy. Finally, three successive French Ordovician crinoid faunas are identified. They show strong palaeobiogeographic affinities with other Gondwanan and peri-Gondwanan assemblages, and in particular with those of the Mediterranean Province. [ABSTRACT FROM AUTHOR]

Two new Early Ordovician crinoids have been discovered in Gondwanan rocks of northwest Argentina. Ramseyocrinus argentinus n. sp., among the most complete for the genus, aids in reconstructing key morphology. Ramseyocrinus is unorthodox with just four radials forming the entire cup, these articulating to five arms above and a tetrameric stem below. Evidence is presented radials comprise A, B, D, and E ray elements (C absent) with B and D radials adjoining to form a compound facet for the C arm. Thus the cup entirely lacks posterior plating; an elongate anal sac projects from the CD tegmen region alongside the C arm. Cup synapomorphies closely link Ramseyocrinus and the Middle Ordovician Tetragonocrinus; inclusion of this clade within disparids is tenuous. Quechuacrinus ticsa n. gen. and sp., increases the paleogeographic range of reteocrinid camerates, previously documented only from Laurentia. This taxon expresses synapomorphies characterizing the Late Ordovician Reteocrinus, demonstrating the antiquity of this morphotype. [ABSTRACT FROM AUTHOR]

Pyrite is consistently found in modern seafloor vesicular basalts and has a sulphur isotopic composition consistent with microbial activity. We present S isotope data from pyrite in Ordovician pillow lavas at localities across the British Isles, which yield a range of δ34S compositions consistent with two components of sulphur: groundmass pyrite (~0 ± 4‰) and 32S-enriched pyrite in the vesicles (−8‰ to −27‰). The latter are recorded from vesicular lavas in four different terranes, representing different settings at the margins of the Iapetus Ocean. Whereas a component of magmatic sulphate is recognized in the groundmass values, the isotopically light data in the vesicles are consistent with microbial reduction of seawater sulphate in sub-seafloor lavas. This is consistent with modern examples and indicates considerable longevity for this sub-seafloor microbial habitat. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

New data on the stratigraphy and faunal assemblages of the Lower Silurian of the Chingiz region are presented. Owing to the discovery of Ruddanian brachiopods in the basal Alpeis Formation, the position of the Ordovician-Silurian boundary has been revised. The stratigraphic range of the Alpeis Formation has been revised to correspond to the range of the Alpeis Horizon in the stratotype and is limited to the beds with the brachiopod Eospirifer cinghizicus and the beds with the graptolites of the Coronograptus gregarius Zone. Beds with Pentamerus longiseptatus of the Donenzhal Horizon are assigned to the Zhumak Formation. A new Ruddanian brachiopod assemblage (ten species) is recognized in the lower part of the beds with E. cinghizicus. [ABSTRACT FROM AUTHOR]

Rhynchonelliformean brachiopods, belonging to 17 genera, are described from the East Baltic Porkuni Regional Stage, correlated with the global Hirnantian Stage. The brachiopod genera Paromalomena, Proboscizambon?, Kinnella, Drabovia, and Coolinia, which are described from the region for the first time demonstrate together with characteristic Hirnantian species of the genera Hirnantia, Dalmanella, Plectothyrella, Eostropheodonta, and Hindella a greater than previously thought commonality of the Baltic fauna with the terminal Ordovician Hirnantia brachiopod fauna of the Kosov Province. The samples containing brachiopods were collected from 43 drill core sections in Central East Baltic. The study area belongs to the Livonian Tongue of the Central Baltoscandian Facies Belt in the Baltic Basin. The brachiopods occur mainly in the skeletal and silty limestone of the Kuldiga Formation within the lower half of the Porkuni Stage. Few brachiopods are known from the sandy or oolitic limestone of the Saldus Formation in the upper part of the stage. Due to excellent preservation some brachiopod species (e.g., Cliftonia psittacina and Dalmanella testudinaria) yield key morphological information, relevant to their classification and phylogeny. This taxonomic study of the East Baltic brachiopods presents essential groundwork for analysis in progress on the distribution and onshore-offshore successions of the Hirnantia brachiopod fauna within both a Baltoscandian and global context. [ABSTRACT FROM AUTHOR]

An unusual, new, giant edrioasteroid Bizarroglobus medusae n. gen. n. sp. is described from the Middle Ordovician Kanosh Shale of west-central Utah. This species has a pattern of ambulacral branching with side ambulacra arising alternately from a main ambulacral trunk, previously undocumented in edrioasteroids. This pattern is interpreted as a strategy for allometrically increasing the feeding surface during ontogeny. Bizarroglobus further differs from other isorophid edrioasteroids in the plating of the peripheral rim, and the presence of pores in the interambulacral plates primarily along the edges of the ambulacra. [ABSTRACT FROM PUBLISHER]