Proetid trilobites from the middle Telychian (Llandovery,Silurian) Ningqiang Formation,Shaanxi, China

Four proetid trilobite species, Chuanqianoproetus guizhouensis Yin in Yin and Li, 1978, C. shuangheensis Wu, 1977, C. sp., and Latiproetus guizhouensis Yin in Yin and Li, 1978, are described from the Ningqiang Formation in Ningqiang County, Shaanxi, China. They are middle Telychian (Llandovery, Silurian) in age. Chuanqianoproetus and Latiproetus are both regarded as members of the subfamily Warburgellinae; the former has been considered to be a junior subjective synonym of Astroproetus, but on the basis of its morphology we argue here that they represent two independent genera. The poorly sorted bioclastic grainstones containing trilobite sclerites may indicate their deposition in turbulent conditions on an open marine platform.     

Middle Telychian (upper Llandovery, Silurian) graptolites from boreholes of northwestern Libya: Their biostratigraphic significance and palaeogeographical implication

A low-diversity but stratigraphically and palaeobiogeographically important graptoloid association comprising Metaclimacograptus flamandi (Legrand), Parapetalolithus meridionalis (Legrand), and Torquigraptus australis Štorch was identified in the core samples of wells A1-66, F1-66 and A1-43 in the Ghadamis Basin of Libya. The former two species have been originally recovered from Algeria. All three taxa are common and widespread in the middle Telychian strata of Spain (Central Iberian Zone and western Iberian Cordillera) and France (Brittany). In European sections, the species are associated with other, moderately diverse graptoloid fauna, which enables a more precise and worldwide biostratigraphic correlation of Saharan boreholes and surface sections. The present faunal association indicates a middle Telychian age (upper crispus, griestoniensis and lowermost crenulata/tullbergi biozones) for the strata and suggests palaeobiogeographical links between North African pericratonic basins and Ibero-Armorican shelves. M. flamandi has not been found outside this NW-Gondwanan realm.     

Revised conodont stratigraphy of the Cellon section (Silurian,Carnic Alps)

The Cellon section, located in the Carnic Alps, is a reference section for the Silurian of the world. The conodont association of the section is revised according to the most recent taxonomy and the biostratigraphy updated in the basis of the recently published zonation schemes. Seventy taxa (species and sub‐species) belonging to 23 genera have been identified, allowing the discrimination of 15 biozones from the upper Llandovery to the end of the P?ídolí . However, some of the uppermost Llandovery and Wenlock biozones, corresponding to black shale intervals, have not been documented.     

Integrated Telychian (Silurian) K-bentonite chemostratigraphy and biostratigraphy in Estonia and Latvia

Kiipli, T., Kallaste, T., Nestor, V. & Loydell, D.K. 2010: Integrated Telychian (Silurian) K-bentonite chemostratigraphy and biostratigraphy in Estonia and Latvia. Lethaia , Vol. 43, pp. 32–44.
The distribution of altered volcanic ash layers (K-bentonites) and Telychian chitinozoans in four East Baltic drill core sections are compared. This information is integrated with graptolite and conodont biozonations to give a precise correlation chart using four different stratigraphical tools: K-bentonite-based chemostratigraphy; chitinozoan biostratigraphy; graptolite biostratigraphy; and, conodont biostratigraphy. Thickness variations in the K-bentonites suggest that the source of the volcanic ash was to the west and north-west.     

Early Silurian(Telychian)rugose coral fauna of Daguan area, northeast Yunnan Province,China

Study on rugose coral fauna of the Sifengya Formation(early Telyehian)and Daluzhai Formation (mid-late Telychian)in Daguan area,northeast Yunnan Province,China was carded out.Rugose coral fauna of the Sifengya Formation included 18 genera and 34 species,while Daluzhai Formation with nine genera,ten species.We described rugose coral fauna(12 genera,19 species)including one new genus and five new species,i.e.Protoketophyllum daguanense gen.et sp.nov..Crassilasma huanggexiense sp.nov.,Pseudophaulactis heae sp.nov.,P.convolutus sp.nov.,and Shensiphyllum minor sp.nov..The characteristics and geological significance of rugose coral fauna of Sifengya Formation and Daluzhai Formation were analyzed.Particularly,mgose coral fauna of the Sifengya Formation represent early Telychian rugosan fauna in the Upper Yangtze region and improve the sequences of early Silurian(Llandovery)mgose coral assemblages in Yangtze region.It is therefore very meaningful to further analyze radiation period of rugose coral fauna in such epoch.     

Early Silurian (Telychian) rugose coral fauna of Daguan area, northeast Yunnan province, China

Study on rugose coral fauna of the Sifengya Formation (early Telychian) and Daluzhai Formation (mid-late Telychian) in Daguan area, northeast Yunnan Province, China was carried out. Rugose coral fauna of the Sifengya Formation included 18 genera and 34 species, while Daluzhai Formation with nine genera, ten species. We described rugose coral fauna (12 genera, 19 species) including one new genus and five new species, i.e. Protoketophyllum daguanense gen. et sp. nov., Crassilasma huanggexiense sp. nov., Pseudophaulactis heae sp. nov., P. convolutus sp. nov., and Shensiphyllum minor sp. nov. The characteristics and geological significance of rugose coral fauna of Sifengya Formation and Daluzhai Formation were analyzed. Particularly, rugose coral fauna of the Sifengya Formation represent early Telychian rugosan fauna in the Upper Yangtze region and improve the sequences of early Silurian (Llandovery) rugose coral assemblages in Yangtze region. It is therefore very meaningful to further analyze radiation period of rugose coral fauna in such epoch. __________ Translated from Acta Palaeontologica Sinica, 2005, 44(2): 229–246 [译自: 古生物学报, 2005, 44(2): 229–246]     

First documentation of Llandovery (Silurian) conodont genus Astropentagnathus in China (Langao,Shaanxi Province) and the age of Baiyaya Formation

Age of the Baiyaya Formation in the Ziyang-Langao region of Shaanxi Province remains debatable. Ten samples were taken for conodont biostratigraphical studies from the Tianwancun section. The first discovery of Astropentagnathus in China indicates that the genus has a wider geographical distribution than previously known. Conodont fauna from the Baiyaya Formation suggests that the lower part of the unit corresponds to the Pterospathodus eopennatus Superbiozone, and its upper part to the lower Wenlock (probably mainly to the Kockelella ranuliformis Superbiozone). Diachroneity of the Baiyaya Formation in the region is confirmed by conodont studies from the Tianwancun and Qiaoxi sections. Further studies are required to find out age-variation of the formation more precisely.     

Aspects of crinoid palaeontology of the North Esk Inlier,Scotland (Silurian,Llandovery, Telychian)

Abstract: The described fauna of well‐preserved Llandovery (Telychian) echinoderms from the North Esk Inlier, including six crinoids, one echinoid and seven starfish species, is mainly allochthonous. Most of these taxa are known only from starfish beds, channel fill deposits probably representing submarine mass flows and preserving a biota probably derived from elsewhere, presumably shallower water. Only one crinoid species, Pisocrinus cf. campana Miller, is recognized as a common fossil away from the starfish beds and is a biostratigraphic marker for the base of the Wether Law Linn Formation, forming part of the Skenidioides‐Cyrtia Association. Crinoid columnals preserved perpendicular to bedding (that is, in putative life position) in Lamont’s bivalve bed, Deerhope Formation, are tentatively interpreted as being in situ by comparison with a similar occurrence in the Silurian of Arisaig, Nova Scotia. Two new species of crinoid are described, the cladid Dendrocrinus? sp. and the columnal morphospecies Pentagonocyclicus (col.) lamonti sp. nov.     

Biotic structure and morphology of patch reefs from South China (Ningqiang Formation, Telychian, Llandovery, Silurian)

Summary Ningqiang Formation (late Telychian, Llandovery, Silurian), characterized by nearly 3000 m of shales in tercalated with carbonates, is situated between Ningqiang (S. Shaanxi Province) to Guangyuan (N. Sichuan Province) adjacent to the northwest margin of the Yangtze Platform. The high diversity “Xiushan Fauna”, and abundant reef development, illustrate a relatively warm and persistent shallo marine environment in these early Silurian sediments. The sequence shows reef radiation after recovery from the end Ordovician mass extinction envents. Multiple horizons of reef-building occurred within a relatively short geological interval and resulted in more than 30patch reefs up to 200 m in diameter and 1–50 m vertically, composed of abundant fossils. Reef biota include frame-building corals, stromatoporoids, bryozoans, and microbialites, and reef-associated oranisms such as crinoids, brachiopods, trilobites, gastropods, nautiloids and ostracods. Three reefrelated biotic associations are recognised: a) reefs dominated by framework with crinoids and microbia; b) reefs dominated by only crinoids and microbia; and c) crinoiddomainated facies. Seven representative reef examples illustrate different morphologies and growth styles. A high terrigenous debris input and shallow epicontinental ramp, which lacked obvious topographic variation, were major controls which resulted in rather simple reefs; sedimentation was apparently the main constraint on lateral and vertical extension of reefs, and prevented large-scale reef complexes developing.     

An Unusually Diverse Llandovery (Silurian) Diplograptid Fauna from the Southern Urals of Russia and Its Evolutionary Significance

This vesiculosus Biozone assemblage of chemically-isolated graptolites from the Orenburg District of Russia was obtained from limestones associated with pillow lavas of the Sakmara Formation of Silurian–Early Devonian age. It comprises 30 species, of which 24 are described. Nine are new, one is a new subspecies, and eight are left under open nomenclature. The assemblage is unique in its diversity of minute biserial graptolites referable to the genera ' Glyptograptus ', Normalograptus , Sudburigraptus , and Metaclimacograptus ; and is unusual in that well-preserved graptolite faunas are rare at this stratigraphical level, which is fixed by the occurrence of Cystograptus vesiculosus (Nicholson) s.l. and Paraclimacograptus innotatus (Nicholson). The following new forms are described: ' Glyptograptus ' tamariscus praecursor subsp. nov., G. mazovoensis sp. nov., G. nikitini sp. nov., G. pavlinovi sp. nov., G. telarius sp. nov., G. zimai sp. nov., Normalograptus legrandi sp. nov., N. melchini sp. nov., N. sobolevskayae sp. nov., and Metaclimacograptus bjerreskovae sp. nov. Five evolutionary lineages are defined within the ' Glyptograptus ' tamariscus (Nicholson) plexus, modifying and extending the pioneer work of Packham (1962). The diverse ' Glyptograptus ' faunas are considered to be a replacement for the Normalograptus fauna which peaked in the late Ordovician and early Silurian. Metaclimacograptus , although reasonably diverse in its speciation, exhibits a conservative style of evolution with little fundamental change throughout the Llandovery. It is suggested that cortical bandages have species-specific dimensions and micro-features. Some problematical micro- and ultrastructural features are described, notably fibrillar textures, parallel to the fusellar margins, in several species.     

Sea level and faunal changes during the latest Llandovery and earliest Ludlow (Silurian)

It is now recognized that the late Telychian and early Gorstian sea level changes are, like many others in the Silurian, of world‐wide extent. The 30–50 m deepening events at these times were between 1 and 2 Ma in duration, so melting continental ice caps appear to be the most probable cause. The faunal changes associated with the two events are respectively very close to the base and the top of the Wenlock Series and thus segregate many of the faunas diagnostic of the Llandovery, Wenlock, and Ludlow series. Permanent extinctions (often followed by radiations) are more prevalent in the graptolites, conodonts, and acritarchs, while benthic faunas are more affected by regional shifts in community distributions. This means that, in the benthos, slowly evolving lineages are the only reliable guides to time. Such phyletic evolution, however, appears to have been unaffected by sea‐level events.     

A late Rhuddanian (early Llandovery,Silurian) trilobite association from South China and its implications

A recovery trilobite association after the end-Ordovician mass extinction, the ‘Encrinuroides’ Association, is documented from the lower Niuchang Formation (upper Rhuddanian, lower Llandovery, Silurian) of Gaojiang, Meitan, northern Guizhou, South China paleoplate, including 10 genera of eight families. Three subassociations of this association could be differentiated, i.e., ascendingly the ‘Encrinuroides’-Eoleonaspis Subassociation, the ‘Encrinuroides’-Aulacopleura (Paraaulacopleura) Subassociation, and the ‘Encrinuroides’-Meitanillaenus Subassociation. The succession of these subassociations in the section indicates a shallowing upward trend of the environment as a result of regional tectonic activities (i.e., the Qianzhong Uplift) against the background of the Rhuddanian global transgression. A relatively complete trilobite succession in South China across the Ordovician–Silurian transition has been summarized and its implications for the trilobite macroevolution of this particular time interval are discussed in detail.     

Late Ordovician palaeoceanographic changes as reflected in the Hirnantian–early Llandovery succession of Jämtland, Sweden

A study of the Upper Ordovician–Lower Silurian strata in Jämtland, central Sweden, shows that large-scale changes in shelf deposition took place close to the systems boundary. These changes include unconformity development and the replacement of a siliciclastic shelf with a carbonate-dominated shelf, suggesting the interaction of allocyclic controls such as changing eustatic sea-level and climate. The 6-m-thick Ede Formation is a key lithosome for interpretation of this transition. Its sediments were deposited in the Caledonian foreland basin, situated east of the closing Iapetus Ocean on the western margin of the Baltic craton. A major part of the late Caradoc to late Ashgill (into the Hirnantian) was characterised by continuous and uniform deposition over wide areas (Kogsta Formation), whereas erosional surfaces and complex lateral facies relationships characterise the Ordovician–Silurian boundary strata (Ede Formation and lateral equivalents). The Ede Formation represents the end of terrigenous deposition, which in the middle Aeronian was followed by regional expansion of carbonate deposition (Berge Formation). A syn-sedimentary erosional surface, with at least 1 m of relief locally, forms the lower boundary of the Ede Formation. This surface is overlain by two types of conglomerate. Lower parts of the Ede Formation consist of medium to thick-bedded quartzites. A second erosional surface with only minor (few centimetres) relief occurs on top of these quartzites. The upper parts of the Ede Formation consist of a thin, basal favositid biostrome overlain by thin bedded, calcareous sandstones, limestones and intensely bioturbated shales. Analysis of stratigraphic boundaries and the facies succession suggests that the lower Ede Formation represents a major downward shift in coastal onlap and by-pass sedimentation that created the lower erosional surface. The erosional surface in the middle of the Ede Formation is inferred to have formed during the subsequent maximum lowstand or as a ravinement surface, and is interpreted as an unconformity. The succession is subdivided into four facies associations, each corresponding to a specific systems tract: (a) a Shale–Siltstone Association (uppermost Kogsta Formation), deposited during a highstand situation in mid-outer shelf areas; (b) a Quartzite Association (the lower Ede Formation), deposited during forced regression in a shoreface environment; (c) a Mixed Carbonate–Siliciclastic Association (the upper Ede Formation), deposited during transgression in a wave-dominated, proximal shelf environment when clastic supply was reduced; and (d) a Micritic Limestone Association (lowermost Berge Formation), deposited during a second highstand situation in a low-energy, offshore environment.

Conodont data, together with a previously reported Hirnantia fauna, constrain the position of the Ordovician–Silurian boundary to the lower 1.65 m of the Ede Formation, or less likely, to the uppermost metre of the underlying Kogsta Formation, i.e., within a 2.65-m-thick uncertainty interval. The base of the Berge Formation is about 4 m above the top of the uncertainty interval, and is dated as being mid-Aeronian in age, suggesting condensation and/or a hiatus close to, or at, the Ordovician–Silurian boundary. These data tie the unconformity and the regional facies change from a siliciclastic to a carbonate-dominated shelf to Late Ordovician–Early Silurian eustatic and climatic changes.     

Cyanobacterial macrophytes in an Early Silurian (Llandovery) continental biota: Passage Creek, lower Massanutten Sandstone, Virginia, USA

A compression macrofossil with structure consisting of mineral-replaced filaments embedded in an amorphous carbonaceous matrix is described as a macrophytic cyanobacterial colony from continental assemblages of the Early Silurian (Llandovery) Passage Creek biota, in the lower Massanutten Sandstone (Virginia, USA). Filaments are predominantly multiseriate and consist of spheroidal crystalline aggregates representing early pyrite (subsequently replaced by iron hydroxides) precipitated preferentially inside cells. Interpretation of the fossils as cyanobacteria is based on close similarities to modern organisms in terms of overall morphology and production of copious extracellular investments, filament and cell sizes, and continental epigeal (freshwater or terrestrial) habitat. This interpretation incorporates data on cyanobacterial taphonomy and mechanisms of diagenetic mineral precipitation. These fossils are part of the oldest macrofossil assemblages documenting well-developed and diverse communities on continents. They provide the earliest direct evidence for cyanobacteria in strictly continental habitats, corroborating the commonly held but poorly documented view that cyanobacteria were among the initial colonizers of continents.     

Faunal and facies changes through the mid Homerian (late Wenlock,Silurian) positive carbon isotope excursion in Podolia,western Ukraine

The late Wenlock is characterized by two global regressive‐transgressive eustatic cycles in association with a double‐peaked positive carbon isotope excursion. The onset of the excursion coincides with an extinction event affecting graptolites (the lundgreni event) and proposed to affect conodonts (the Mulde Event) and proliferation of non‐skeletal carbonates. In order to test the hypothesized relationships between eustatic and ecological changes, the tropical carbonate Homerian succession in Podolia has been examined with respect to conodont, sequence and δ¹³C stratigraphy. Four depositional sequences (DS) have been identified. The onset of the δ¹³C excursion occurs at the boundary between DS1 and DS2, corresponding to a forced regression of proposed glacioeustatic origin. The following rapid eustatic transgression associated with the highest δ¹³C values of 5.2‰ includes a higher‐order shallowing episode recorded in Podolia as normal regression and a boundary between DS2 and DS3. This interval is distinguished by the presence of oncoids and thrombolitic buildups. The latest Wenlock eustatic fall and the corresponding second peak of the δ¹³C excursion corresponds in Podolia to a stratigraphic gap. The first δ¹³C peak (top of DS1 and DS2) corresponds to the O. bohemica longa conodont Zone, the interval between the two peaks (DS3) – to K. ortus absidata and C. murchisoni zones, and DS4 is tentatively placed in the lowermost Ludlow Series. The record of relative sea‐level changes in Podolia is consistent with reconstructions based on successions in England and Sweden. The moderate drop in conodont taxonomic richness may reflect the primary depositional control over their proposed extinction.     

TELYCHIAN (LLANDOVERY, SILURIAN) BIVALVES FROM SPAIN

Abstract:  Twenty species of bivalves (14 new) and 14 genera (six new) are described from two localities in the Silurian, upper Telychian, Oktavites spiralis Biozone of Spain: Cardavia cathleenae gen. et sp. nov., C. hafi sp. nov . , C. stefani sp. nov.; Copenychia franta gen. et sp. nov., C. pristina sp. nov.; Stolidotus marco sp. nov.; Telycardia malinka gen. et sp. nov.; Silurinka vetula gen. et sp. nov.; Bolsopteria lentilka gen. et sp. nov.; Nennapteria ibericola gen. et sp. nov., N. ollicula sp. nov.; Actinopteria dakryodes sp. nov., A. isabelae sp. nov. and Dceruska hispanica sp. nov. They comprise two closely related communities, the Copenychia-Cardavia-Actinopteria Community and the Dceruska-Copenychia-Stolidotus Community, which belong to the Snoopyia Community Group. The occurrence of Dceruska Barrande, 1881, Dualina Barrande, 1881, Patrocardia Barrande, 1881, Silurinka , gen. nov., Slava Barrande, 1881 and Stolidotus Hede, 1915 in the Telychian of the Central Iberian Domain, Spain, supports palaeogeographical relationships with other Lower Silurian regions of north Gondwanan and Perunican Europe: the Carnic Alps (Austria), the Montagne Noire (France), Sardinia (Italy) and the Prague Basin (Bohemia), and also to Avalonia: the Welsh Borderland (Great Britain) and Baltica–Skåne (Sweden). These genera together with the new genera Cardavia, Copenychia (the earliest known representatives of the Silurian family Cardiolidae), Telycardia (the oldest known representative of the family Praecardiidae) and Silurinka belong to a Bohemian type of bivalve. Bolsopteria lentilka is closely related to Bolsopteria elliptica (Hind, 1910) from the Aeronian (middle Llandovery) of Scotland.     

Late Ordovician and early Silurian Proetida (Trilobita) from north-western and central Europe

Species belonging to genera of three families of the Proetida (Proetidae, Rorringtoniidae and Toernquistiidae) are described from the upper Ashgill of southern Sweden, and the same or related species noted from the adjacent parts of northern and central Europe. Proetidae are represented by Paraproetus brevifrons (Angelin), Ogmocnemis irregularis Kielan, Ogmocnemis jaanussoni sp. nov. and Parvigena putealis sp. nov.; it is argued that all belong to the Cornuproetinae, not Tropidocoryphinae where they were previously classified. Ogmocnemis is resurrected for some Upper Ordovician species included previously in Decoroproetus . The rorringtoniid genera Rorringtonia and Madygenia are recognised for the first time in southern Sweden, and it is argued that these are probably closely related, and both are included in the same family; both are recorded for the first time from Silurian (Llandovery) strata. Zetaproetus is claimed to be a junior subjective synonym of Rorringtonia. Solariproetus , first described from north-west China, is assigned to the Toernquistiidae as a late, derived member, and S. prosthemesos sp. nov. is described from late Rawtheyan strata in the Holy Cross Mountains, Skåne and the English Lake District. Comments are given on the stratigraphical and palaeogeographical distribution of these taxa.     

扬子台地西北缘志留纪笔石Oktavites spiralis (Geinitz, 1842)发育过程研究

Oktavites spiralis(Geinitz,1842)是志留系特列奇阶(Telychian)的笔石带化石,其形态特征明显,在全球范围内广泛分布,地层对比意义较强。然而,该种宽泛的化石定义以及缺乏居群变异研究,造成了对该化石延限的争议,不利于地层的精确对比。笔者对产自陕西紫阳、岚皋地区特列奇阶Oktavites spiralis带至Cyrtograptus lapworthi笔石带的45个Oktavites spiralis不同发育阶段的幼体标本进行研究,建立了较完整的发育序列,从而对该种的始部特征有了更为深入的了解,增加了描述的精确性。同时,通过始部特征的对比研究,可将Oktavites spiralis和与之共生的Oktavites contortus(Perner,1897)明确区分为2个独立的种。此外,对Oktavites spiralis和Oktavites contortus发育过程的研究,也可成为该属进一步精确厘定的主要依据之一。     

Harnessing stratigraphic bias at the section scale: conodont diversity in the Homerian (Silurian) of the Midland Platform,England

Fossil abundance and diversity in geological successions are subject to bias arising from shifting depositional and diagenetic environments, resulting in variable rates of fossil accumulation and preservation. In simulations, this bias can be constrained based on sequence‐stratigraphic architecture. Nonetheless, a practical quantitative method of incorporating the contribution of sequence‐stratigraphic architecture in community palaeoecology and diversity analyses derived from individual successions is missing. As a model of faunal turnover affected by the stratigraphic bias, we use the ‘Mulde event’, a postulated mid‐Silurian interval of elevated conodont turnover, which coincides with global eustatic sea‐level changes and which has been based on regionally constrained observations. We test whether conodont turnover is highest at the boundary corresponding to the ‘event’ and post‐‘event’ interval against the alternative that conodont turnover reflects habitat tracking and peaks at facies shifts. Based on the previously documented, parasequence‐level stratigraphic framework of sections in the northern and central part of the Midland Platform, the relative controls of sequence‐stratigraphic architecture, time and depositional environment over conodont distribution are evaluated using permutational multivariate analysis of variance. The depositional environment controls the largest part of variability in conodont assemblage composition, whereas the postulated ‘Mulde event’, or genuine temporal change in conodont diversity, cannot be detected. Depending on the binning of the stratigraphic succession, contrasting diversity and turnover patterns can be produced. The simple approach proposed here, emulating partitioning of β diversity into spatial and temporal components, may help to constrain the stratigraphic bias, even at the scale of an individual section.     

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.