Age of the Silurian Wuxiahe Formation in Langao,Northwest China: New conodont data

A recent study of conodonts from the Wuxiahe Formation (lower to middle part) in the Ziyang-Langao region suggested its age of middle Telychian (Llandovery) to lower Sheinwoodian (Wenlock), contradicted by subsequent graptolite studies indicating an age of late Telychian for the same interval. New samples from the Qiaoxi section for conodonts to re-access the age of the Wuxiahe Formation collected in this study show that the lower to middle part of the formation belongs to the Pterospathodus amorphognathoides amorphognathoides Biozone, suggesting the age of late Telychian; thus, the Llandovery–Wenlock boundary in the section is most probably higher than previously estimated, but its precise position is not determined since the identification of the Wenlock graptolite Cyrtograptus cf. lundgreni in the section is to be further confirmed. Based on the conodont faunas recognized in the Qiaoxi and Tianwancun sections, the base of the Wuxiahe Formation in the Ziyang-Langao region is diachronous, i.e., not higher than the upper Telychian Pterospathodus amorphognathoides amorphognathoides Biozone at Qiaoxi, but not lower than the lower Sheinwoodian Kockelella ranuliformis Biozone at the Tianwancun setion.     

日本志留纪至三叠纪牙形刺生物地层

本文系统地回顾了日本志留纪至三叠纪牙形刺研究的历史和现在的成果。志留纪牙形刺只有少数零星的报道,没有建立化石带;早泥盆世已建立了５个牙形刺组合,没有中、晚泥盆世的记录;石炭纪有８个牙形刺带,其中晚石炭世３个牙形刺带;二叠纪５个牙形刺带或动物群,其中,中、晚二叠世各１个带（动物群）;三叠纪可划分出１４个牙形刺带。     

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.     

内蒙古达茂旗巴特敖包地区包尔汉图剖面牙形刺生物地层

内蒙古达茂旗(达尔罕茂明安联合旗)巴特敖包地区志留纪、泥盆纪碳酸岩相地层发育,本区珊瑚、腕足类、层孔虫等底栖大化石的研究工作已有一定基础。但志留纪、泥盆纪地层在时代确定和对比上还存在很多问题,必须用主导化石门类牙形刺加以解决。研究表明：包尔汉图剖面的顶部属泥盆系无疑,应归入阿鲁共组,而不是西别河组;巴特敖包地区的海侵,始于罗德洛统卢德福德阶(Ludfordian)早期。本剖面没有发现文洛克世和罗德洛世早期的海相沉积。本文描写了一个志留纪牙形刺新种：Ozarkodina uncrispa sp．nov．。     

Zur Biologie, Taxonomie und Chronologie der Conodonten

The actual state of knowledge concerning the conodont animal is critically reviewed. All soft tissue documented by the specimens of the conodont animal were interpreted by the British collectors as Craniota (Vertebrata) features. Opinions on the precise affinities, however, remain controverse: The alleged chorda could have been a gut, bilateral symmetry, myomery, apatitic biomineralisation occur also in Invertebrata, caudal fins do in Chaetognatha. Even the lobes in the capital area interpreted as sensory organs could have served as aiding organs for food intake. Therefore, the originally sensational findings are reduced to the core issue that the conodont animal had an eel-like body and at the blunt end of it, behind peculiar lobes, the mineralized conodont elements were arranged. As a consequence, a relationship to the Protochordata cannot be excluded. A systematic position of the conodont animal as possible Vertebrata is likely only if organized below the Ostracodermata which is particularly so because conodonts occur so early in the Cambrian. In the second part of the article conodonts are discussed as guide fossils. The comprehensive, empirically grown taxonomy of the single elements is the prerequisite for recognizing outstanding, high resolution stratigraphy. In comparison, a multielement taxonomy remains as long problematical, as it is based on assumed, mostly statistically reconstructed rather than on natural multielement apparatuses. Taxonomical and nomenclatorial operations built on assumed apparatus affinity can bear heavily on nomenclature and stratigraphy of platform elements. It can be shown at the example of the Devonian that the platform elements have provided particularly in the pelagic facies a Standard Conodont Zonation that covers time almost without any gaps. The basis for this is that platform single element species and their phylogenetic development are extra-well known. In a special paragraph, history and applicability of the Standard Zonation is discussed in details. Different conodont biofacies are developed between the pelagic realm where the Standard Zonation originated, and the coastal areas so that conodonts can indicate temporal and bathymetric relationships of the mother rocks. In addition alternative conodont zonations were introduced mainly for the shallow water. Because of their conspicuous stratigraphic significance in the Devonian, conodonts were employed by International Committees to redefine Series and Stage Boundaries. For the boundary selection species were utilized from phylognetic lineages as only from tight evolution their point of origination could be well identified and recognized in worldwide correlation. The GSSPs (Global Stratotype Section and Point) within the Devonian are discussed in detail. In recent times, attempts are made at calibrating the duration of conodont zones on the basis of their well known rate of evolution and high temporal resolution. These analyses have to be continued in order to demonstrate the absolute time relationship of condont zones in more and continuous detail. Currently the phyletically controlled Standard Conodont Zonation is the authoritative stratigraphic method in the Devonian. It has provided together with the GSSPs precise and valuable fix points for a Global Time Scale (GTS). In combination with additional stratigraphie methods the Standard Conodont Zonation may provide further refinements in the future.     

Evidence of parallel evolution in the dental elements of Sweetognathus conodonts

The repeated emergence of similar morphologies in the dental elements of Permian Sweetognathus conodonts has been a hypothesized example of parallel evolution. To test if morphological parallelisms occur between isolated Sweetognathus lineages, this study uses two-dimensional-based geometric morphometrics combined with a revised and expanded phylogeny of Permian Sweetognathus conodonts to quantify dental element trait distributions and compare the phenotypic trajectories between lineages. A hierarchical clustering method was used to identify recurrent species pairs based on principal component scores describing their morphological variation, with the further incorporation of widely used ecological metrics such as limiting similarity and morphological overlap. Our research implies that a major contributor to conodont diversity in Palaeozoic marine trophic networks is the emergence of recurrent parallel morphologies via disruptive and directional selection. This study illustrates the mechanisms through which conodonts achieved their status as hyper-diverse predators and scavengers, contributing substantially to the complexity of Palaeozoic marine communities.     

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

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

河北唐山下奥陶统牙形刺生物地层的新认识

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

辽河断陷盆地西部晚寒武世至早奥陶世牙形石生物地层

辽河断陷盆地西部凹陷古潜山顶部地层的时代 ,自 70年代末期以来 ,一直被认为属于中、上元古代。本文通过在总面积为 60 0 km2 的西部凹陷中段系统、详尽的牙形石生物地层研究 ,并结合疑源类、小壳化石以及岩石地层学资料 ,确认研究区内古潜山顶部地层的时代主要为晚寒武世至早奥陶世。中、上元古代地层在研究区内虽然存在 ,但分布极其局限。从而 ,彻底改变了2 0年以来对该地区古潜山地层划分和对比上的传统认识。     

Frasnian conodonts from the eastern Russian Platform

The Frasnian conodonts of the eastern Russian Platform from the Timan in the north to the Orenburg Region in the south are characterized in detail both paleontologically and stratigraphically. This paper is a continuation of a previously published monograph (Ovnatanova and Kononova, 2001) on the Frasnian conodonts of the shallow-water strata of the central Russian Platform, where polygnathids prevail. The conodont assemblages from the shallow-water and basinal sections of the Volga-Ural province and Southern Timan are analyzed. Problems and difficulties associated with the correlation of the shallow-water and deep-water Frasnian sections of the eastern Russian Platform and their correlation with the existing zonal conodont scales are discussed. The correlation between the deep-water Mendym deposits and the shallow-water Rechitza and Voronezh strata of the Volga-Ural province with the Vetlasyan and Sirachoi deposits of the Southern Timan is substantiated. The stratotype of the Semiluki Regional Stage of the Central Devonian Field contains equivalents of the lowermost beds of the Domanik Formation (unit 1), based entirely on polygnathids. Phylogenetic reconstructions for Palmatolepis and Polygnathus are suggested based on the ontogenetic series for some species of these two genera and the presence of transitional forms between some of the species. Based on these phylogenetic reconstructions, conodont zonal scales for the shallow-water and deep-water sections of the Frasnian Stage of the Russian Platform are proposed and their correlation with the existing conodont zonal scales is also adduced. Some aspects of biofacies control are considered based on the distribution of conodonts in the sections studied. In Systematic Paleontology, 91 conodont species of the genera Ancyrodella, Mesotaxis, Palmatolepis, and Polygnathus are described, including the new species Palmatolepis menneri, P. kaledai, P. acutangularis, and Polygnathus reitlingerae. DEDICATION To the blessed memory of the outstanding geologist Vladimir Vladimirovich Menner     

华南中泥盆世艾菲尔期浅海相四射珊瑚的组合特征和古生物地理区系

虽然在华南中泥盆世艾菲尔期(Eifelian)较深水或斜坡相地层中产有许多国际标准的牙形类带化石,但在广阔的浅海相地层中却很难寻觅到其踪影。华南浅海相沉积地区是否缺失艾菲尔阶?在野外众多剖面的实地考察中表明,从下泥盆统埃姆斯阶到中泥盆统吉维特阶都是连续沉积,中间并没有发现地层的缺失或间断现象。浅海相的艾菲尔阶与其上覆的吉维特阶和下伏的埃姆斯阶都是连续沉积,说明可能是由于海水太浅,不太适合那些国际标准分子的生存而已。艾菲尔期中期末发生一次生物灭绝事件(Mid-Eifelian event),favositids,heliolitids和许多古老类型的珊瑚在地球上灭绝。华南艾菲尔期四射珊瑚可以划分成下、上两个完全不同的组合:1)Utara-tuiasinen sis-Sociop hyllum minor组合(牙形类partitus带—costatus带);2)Columnaria spinosa-Dendrostella praerhenana组合(牙形类australis带—kocklianus带)。     

滇东,黔西和桂北不同相区的三叠纪牙形刺

本文描述了采自滇东、黔西和桂北不同相区２８个剖面的三叠纪牙形刺共２２属７９种。由于不同相区的牙形刺动物群具有不同的特征,因此不同性质的牙形刺动物群的分布与岩相和古沉积环境关系非常密切。本区三叠纪牙形刺可明显分为两大类型,即“台地型”和“盆地型”。本文论述了牙形刺动物群的分布与岩相相带之关系,组建了不同相区的牙形刺序列,同时讨论了二叠－三叠系界线。     

Soft anatomy and the affinities of conodonts

Recent claims that conodonts are members of the Craniata or Vertebrata are based in part upon soft tissue features that have been preserved in a small number of specimens. These features include what appear to be radials in the caudal fin and paired structures that have been identified as eye remnants. The evidence for radials is limited, but credible. However, the anatomy of extant cyclostomes suggests that the paired structures are more reasonably interpreted as otic capsules than the remnants of sclerotic eye capsules. Moreover, even if these structures are the remnants of eyes, conodonts might equally well be a sister group to the craniates as a member of that group. Aside from these paired structures, conodont fossils exhibit no features that are suggestive of a cartilaginous skeleton. Given that cyclostome fossils sometimes show evidence of the cartilages of the head, the apparent absence of a similar skeleton in conodont animals calls into question the claim that they are craniates. The simple single chevron shape of conodont myomeres also suggests that they lie outside of the Craniata. All living craniates have double-chevron myomeres as adults, whereas simple myomeres of the conodont type are found in the non-craniate cephalochordates. Thus the available soft tissue evidence suggests that conodonts are best regarded as the sister group of the craniates.     

Overgrowths of large authigenic apatite crystals on the surface of conodonts from Cantabrian limestones (Spain)

Conodonts from the middle to upper Paleozoic limestones of the Cantabrian zone commonly show apatite overgrowths. A large crystal microtexture observed under the SEM corresponds to local rims of euhedral to subhedral apatite crystals, which were preceded by the neoformation of smaller crystals. Four types of this microtexture (blocky, columnar, fan, and denticular) are described on different areas of the oral surface of conodonts, whereas dissolution features may be present in the basal cavity area. The distribution of these types of microtexture in different areas of conodont morphology suggests a general trend to neocrystallization, where crystal size increases towards the top of the conodont ornamentation and a chemical gradient controls the crystalline growth. This arrangement is widely related to the surface morphology and to the general conodont histology. The large crystal microtexture grows during early diagenesis from near surface to moderate burial and is linked to the known secondary apatite cement present in natural fused clusters of conodonts. The features described here are also compared to microtextures developed on conodonts during low- to medium-grade metamorphic conditions, where phosphate in solution is available.     

Silurian to Mississippian series of the eastern Catalan Pyrenees (Spain), updated by conodonts, foraminifers and algae

Stratigraphic sections and microfossils samples from the upper part of the “Graptolitic Shales-Orthoceras Limestones” and from the Camprodon Formation lying in the area of Camprodon, eastern Pyrenees, Spain, have been studied. Some beds at the top of the “Graptolitic Shales-Orthoceras Limestones” correspond to the Torres Member of the Rueda Formation, and conodont faunas, indicating a Lochkovian age, are described. The Camprodon Fm. is interpreted to be turbidites deposited in deep sea fans, although slope deposits prevail in the eastern sections. One reworked carbonate clast from the Camprodon Fm. provided a valuable early Ludlow conodont fauna, from the Kockelella crassa Zone, reported for the first time in the Iberian Peninsula. Late Devonian conodonts and late Visean (Asbian-Brigantian) foraminifers and algae were also obtained from reworked limestone clasts, and latest Visean or Serpukhovian foraminifers from the sandstone matrix in the Camprodon Fm. The studied microfossils suggest a late Mississippian age for the Camprodon Fm. instead of the previously assigned late Silurian-Lochkovian age. This age must be considered when discussing the distribution of the Culm Facies in the Pyrenees and the significance of the contact between the Camprodon Fm. and the underlying “Graptolitic Shales”.     

湖南花垣中寒武世晚期至晚寒武世早期牙形石动物群

本文描述了湖南花垣排碧剖面中寒武世晚期至晚寒武世早期牙形石动物群的２个新属８个新种。论述了在中国南部首次建立的湖南花垣中－上寒武统牙形石带与华北和东北南部相应牙形石带的对比依据,概述了中国寒武纪牙石研究的简史和现状。     

Evolution of Permian conodont provincialism and its significance in global correlation and paleoclimate implication

The main components of Asselian through Artinskian conodont faunas found around the world are basically the same, and the provincialism is indicated only by less common endemic elements such as Gondolelloides and New Genus A Henderson in North Pangea, Sweetognathus bucaramangus around the equator and Vjalovognathus in eastern Gondwana. Provincialism is marked by differences at the species level of Mesogondolella, Neostreptognathodus and Sweetognathus during the Kungurian, and becomes very distinct with differences at the genus level during the Guadalupian and Lopingian. Three provinces of Permian conodonts, referred to as the North Cool Water Province (NCWP), the Equatorial Warm Water Province (EWWP) and the peri-Gondwana Cool Water Province (GCWP), are recognized. The NCWP is marked by Gondolelloides in the early Cisuralian, dominance of Neostreptognathodus and no or rare Sweetognathus in the late Cisuralian, dominance of Merrillina and Mesogondolella and absence of Sweetognathus in the Guadalupian, and dominance of Merrillina and Mesogondolella and absence of Iranognathus in the Lopingian. The EWWP is characterized by the absence of Gondolelloides and Vjalovognathus in the Cisuralian, abundance of Sweetognathus and Pseudosweetognathus in the Kungurian (late Cisuralian), Jinogondolella and Sweetognathus in the Guadalupian, and Clarkina and Iranognathus in the Lopingian. The GCWP is marked by Vjalovognathus, Merrillina in the Cisuralian, Vjalovognathus, Merrillina and Mesogondolella in the Guadalupian, and Vjalovognathus and Merrillina in the Lopingian. Mixed faunas are recognized in regions bordering between the EWWP and GCWP including Western Timor during the Artinskian, Pamirs during the Kungurian and the Salt Range during the Guadalupian and Lopingian.

Three different conodont zonations are proposed, one for each of the three conodont provinces. Four potential horizons for inter-provincial correlation of Permian conodonts are recognized. They are in ascending order: (1) the first appearance of Sweetognathus whitei, which is closely related to the last occurrence of Carboniferous-type conodonts such as Streptognathodus and Adetognathus; (2) the first appearance of Neostreptognathodus pequopensis; (3) the base of the Jinogondolella nankingensis Zone; and (4) the base of the Clarkina postbitteri–Iranognathus erwini Zone.

The spatial and temporal distribution pattern of Permian conodonts suggests that temperature is the primary controlling factor. Evolution of Permian conodont provincialism reveals a glaciation during the Asselian and Sakmarian, a global warming during the Artinskian, a climate cooling in North Pangea during the Kungurian, a continuation of Kungurian climate trends in the Guadalupian, a relatively minor warming during the Wuchiapingian, a returned cooling in the Changhsingian and Lower and Middle Griesbachian, and a global warming in the Late Griesbachian, which ended the Permian conodont lineage.     

镇江地区上二叠统—下三叠统的牙形刺

详细描述了采自镇江附近１１－１，１１－２，７９－８号等钻孔的上二叠统—下三叠统的牙形刺化石共１１属２８种，建立了６个牙形刺化石带，其中上二叠统１个、下三叠统５个，并以牙形刺带为基础，进行了国内外对比。     

Allometry in Anisian (Middle Triassic) segminiplanate conodonts and its implications for conodont taxonomy

Conodonts are a clade of chordates and are valuable indicator fossils for biostratigraphy. The segminiplanate (neogondolelliform) conodonts represent a major morphological group ranging from upper Carboniferous to Upper Triassic marine sediments. However, the morphological similarity of segminiplanate P₁ elements generates problems for taxonomy, especially in the Permian and Triassic clades. This paper represents the first study of morphological variation in Triassic segminiplanate conodonts using a geometric morphometric approach. The laminar microstructures observed in conodont cross‐sections indicate that, within our analysed specimens, smaller conodonts with fewer laminae are generally from an earlier ontogenetic stage while larger conodonts with more laminae are from a later stage of ontogeny. Using linear regressions between relative warp scores from both upper and lateral views and conodont length, we demonstrate strongly allometric growth patterns for the species Paragondolella bifurcata Budurov & Stefanov. Our results indicate that the species‐group taxon Pg. praeszaboi bystrickyi (Kovacs et al.) is an early growth stage of Pg. bifurcata and thus synonymous. We suggest that the allometry of conodonts should be considered seriously, especially when there are numerous transitional morphologies between large‐ and small‐sized conodonts. Reconstructing the ontogenetic series and using larger‐sized conodonts within the numerous transitional morphologies in the population of a rock sample for the definition of new species are suggested for future studies.     

Conodont anatomy, chordate phylogeny and vertebrate classification

Interpretations of conodont anatomy and affinity continue to generate controversy. Fossilized soft-tissue evidence indicates that conodonts possessed eyes, extrinsic eye muscles, a notochord, myomeres, a differentiated tail with fin radiais, possible otic capsules and possible branchial structures. Indirect evidence suggests a differentiated brain and cartilaginous head skeleton. The multi-component phosphatic tissue complexes of the conodont feeding apparatus cannot be compared to the amorphous apatite of extant agnathan otoliths. By limiting cladistic analysis to a restricted selection of these characters the hypothesis that conodonts are a sister group of the clade comprising extant hagfish, lampreys and gnathostomes can be supported. However, exhaustive analysis of a more complete character-set strongly supports the hypothesis that conodonts are more derived than hagfish. From a taxonomic perspective, these two hypotheses have no effect on how conodonts should be classified. Whether they are a stem group (the former hypothesis) or part of the crown group (the latter), conodonts are clearly part of the total group Vertebrata (=Craniata).