Ordovician conodont biostratigraphy of the Willara Formation in the Canning Basin,Western Australia

The conodont fauna from the Willara Formation, a carbonate-dominated stratigraphic unit widely distributed in the subsurface Canning Basin of Western Australia, is represented by 41 species, including a new species, Erraticodon neopatu Zhen n. sp. The Jumudontus gananda and Histiodella altifrons biozones are recognized in the lower and upper parts, respectively, of the Willara Formation. Deposited primarily in shallow nearshore settings, the Willara Formation is characterized by the occurrence of predominantly long-range coniform species of Triangulodus, Scalpellodus, Drepanoistodus, Drepanodus, and Kirkupodus. Several widely distributed age-diagnostic species, including Histiodella altifrons, Histiodella holodentata, Histiodella serrata, and Jumudontus gananda, serve as keys for biostratigraphic analysis and correlation. Our study also shows that the basal and top boundaries of the Willara Formation are diachronous across the basin, extending from the middle Floian (Oepikodus communis Biozone) to middle Darriwilian (Histiodella holodentata-Eoplacognathus pseudoplanus Biozone). This contribution provides crucial new biostratigraphic data for precise correlation of the Willara Formation with its time equivalents regionally and internationally.     

Integrated radiolarian and conodont biostratigraphy of the Middle Permian Gufeng Formation (South China)

Radiolarians are usually abundant in chert sequences and they have thus been widely used for the biostratigraphy of deep-water sediments. However, there are many difficulties in the correlation of radiolarian biostratigraphic schemes with the standard conodont zones. In this study, 21 radiolarian species were extracted from the Gufeng Formation that crops out in the Luojiaba (LJB) section (western Hubei, China), together with 5 co-occurring conodont species. In this way, it is the first time that the Pseudoalbaillella globosa, Follicucullus monacanthus and F. scholasticus radiolarian zones can be directly correlated with the Jinogondolella nankingensis gracilis, J. aserrata and J. postserrata conodont zones. Accordingly, the 3 radiolarians zones are now firmly correlated with the Roadian to middle Capitanian interval (Middle Permian).     

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.     

An updated Telychian (Late Llandovery, Silurian) conodont zonation based on Baltic faunas

Five conodont zones, Pterospathodus eopennatus ssp. n. 1, P. eopennatus ssp. n. 2, P. amorphognathoides angulatus , P. a. lennarti and P. a. lithuanicus , are described in the interval previously known as the P. celloni Zone. The new zones are grouped into two superzones: the first two form the P. eopennatus Superzone and the other three the P. celloni Superzone. All zones correspond to the intervals of the total ranges of the nominal taxa and to the boundaries between the zones to the levels at which one taxon was evolutionally replaced by another. The lower boundary of the P. a. amorphognathoides Zone is redefined. The P. eopennatus ssp. n. 2, P. a. angulatus and P. a. amorphognathoides zones are further subdivided into the Lower and Upper subzones. Although the zones described are mainly based on data from Estonia, they can be recognized all over the world, in most sections containing Telychian strata and from where adequate data are available. Most of the subzones can so far be applied only in a limited area.     

A refined graptolite biostratigraphy for the late Ordovician–early Silurian of central Wales

Morphometric analysis of graptolites from the persculptus and acuminatus biozones of central Wales identifies four successive morphospecies of normalograptids. These graptolites can be used for biostratigraphical subdivision of these strata as follows: (i) an early persculptus Biozone interval containing broad forms with geniculate thecae that have the morphology of Persculptograptus persculptus with an early insertion point for the full median septum (theca 1¹); (ii) a supra‐adjacent level of early persculptus Biozone age, with narrower, parallel‐sided forms, that have been referred to as Normalograptus? aff. parvulus and have a slightly later insertion point for the full median septum (theca 1²); (iii) a third interval, encompassing the later part of the persculptus Biozone to the early acuminatus Biozone, with Normalograptus? cf. parvulus, which has the full median septum delayed to the level of theca 3–7; and (iv) a younger interval, in the mid‐acuminatus Biozone with Persculptograptus cf. persculptus specimens that do not display the median septum on its reverse side. These taxa can be used for refined biostratigraphy and correlation in the late Ordovician and early Silurian of central Wales. The progressive delay in the insertion of the median septum in these taxa may have wider application for the correlation of the interval immediately after the Hirnantian glacial maximum.     

A review of early (Silurian and Devonian) vertebrate biogeography and biostratigraphy of China

A review of the vertebrates within the Silurian and Devonian of China suggests a more detailed picture of palaeobiogeographical distribution than previously possible. Although the localities are commonly in rocks of continental aspect, marine formations also are present nearby. Of over 60 agnathan and fish genera known, only 5 placoderms (Givetian-Famennian) are cosmopolitan. Endemic patterns of distribution within China relate to the well-known tectonic (basinal or platformal) regions. Silurian vertebrates occur in southern, eastern and western parts of the country and are familiar from horizons as low as Llandovery. Devonian vertebrates include a wide range of endemic forms, which provide evidence of more than six distinct biostratigraphic assemblages in South China and five biogeographical realms.     

The conodont animal

A unique specimen of a small, elongate, soft-bodied animal from the Lower Carboniferous of the Edinburgh district, Scotland, is described. The head expands anteriorly into two lobate structures flanking a central lumen; behind this lies a conodont apparatus, apparently in situ, consisting of an aligned set of ramiform elements followed by a pair of ozarkodiniform elements and one of platform elements. From the morphology of the platform elements the animal has been identified as Clydagnathus? cf. cavusformis. Repeated structures which may represent segments are evident in the posterior part of the trunk, which bears a posterior and a caudal fin, each supported by rays. The animal shows similarities to both chordates and chactognaths, but the evidence supports its assignment to a separate phylum, the Conodonta. The function of the conodonts remains equivocal, but it seems more likely that they served as teeth than as internal supports.     

Toward an improved discrimination of outer membrane proteins using a sequence-based approach

This article offers a novel sequence-based approach to discriminate outer membrane proteins (OMPs). The first step is to use a new representation approach, factor analysis scales of generalized amino acid information (FASGAI) representing hydrophobicity, alpha and turn propensities, bulky properties, compositional characteristics, local flexibility and electronic properties, etc., to characterize sequences of OMPs and non-OMPs. The subsequent data is then transformed into a uniform matrix by the auto cross covariance (ACC). The second step is to develop discrimination predictors of OMPs from non-OMPs using a support vector machine (SVM). The SVM predictors thus successfully produce a high Matthews correlation coefficient (MCC) of 0.916 on 208 OMPs from non-OMPs including 206 α-helical membrane proteins and 673 globular proteins by a fivefold cross validation test. Meanwhile, overall MCC values of 0.923 and 0.930 are obtained for the discrimination OMPs from the α-helical membrane proteins and the globular proteins, respectively. The results demonstrate that the FASGAI-ACC-SVM combination approach shows great prospect of application in the field of bioinformatics or proteomics studies.     

Polygonal ornament in the conodont Siphonodella: an internal record

Polygonal 'pit' ornamentation has been reported from a wide range of conodont genera, typically distributed semi-continuously over the upper surface. Observations using the Scanning Electron Microscope (SEM) on the interior of Siphonodella have revealed polygonal pitting over the external surface of inner lamellae. The importance of this observation for the development of Siphonodella is discussed. ▭ Siphonodella, polygonal ornament, microstructure, growth.     

Causal biostratigraphy

Causal biostratigraphy means an approach to stratigraphic problems based on ecosystem analysis of interrelations between geological events and organic evolution. Thc succession of ecosystems is controlled mainly by climatic cycles. Stratigraphic units correspond to palececosystems. The units of higher ranks which are defined by changes of major biomes correspond to paleobiospheres. Their boundaries are designated by replacement of dominant types within the stratoecotones. Reconstruction of catenae, analysis of vicarious catenae systems, and correlation by cliserer are among the most useful methods of causal biostratigraphy.     

Systematic biostratigraphy: A solution to problematic classification systems in biostratigraphy

Systematic biostratigraphy is based on the exclusive use of monophyletic marker taxa. Non-monophyletic, or artificial, marker taxa have been shown to change biostratigraphic correlations, a situation that can be rectified by using systematics to ensure that marker taxa are monophyletic or natural. Both hypothetical and real examples demonstrate the validity of the methodology. The foraminiferal genera Praemurica and Parvularugoglobigerina are examples of non-monophyletic marker taxa. Cladistic results permit the reclassification of both genera, and a revision of foraminiferal biostratigraphy. Systematic biostratigraphy ensures the use of monophyletic marker taxa, preventing artificial classifications from hindering biostratigraphic correlations and producing more accurate, and stable, biostratigraphic zonations.     

The hydrodynamics of conodont elements

Accurate palacobiological interpretation of the fossil record requires an assessment of biostratinomic processes. Samples which have undergone significant post-mortem sorting reflect only the hydrodynamic regime prevalent at the time of deposition and not the original faunal composition. Conodont bedding plane assemblagcs are rare and many conodont taxa are known only through reconstructions of apparatuses using empirical techniques. These methods require large collections where the elements have undergone no significant post-mortem transportation. In this paper measurements of settling velocities are used to predict relative hydrodynamic behaviour in a current. The settling velocity of a particle is of about the same magnitude as the current required to entrain that particle. Conodont elements rotate during fall, spinning about a central axis. Elements with equal Reynolds numbers may have different drag coefficients indicating that shape is an important factor in determining conodont element hydrodynamics. In a current of increasing velocity the predicted order of entrainment of elements of the same equivalent size is as follows: Polygnathus S. Ancyrodella Pa. Polygnathus Pa. Palmatolepis Pa. Polygnathus Pb. lcriodus Pa. Conodont elements grow by accretion of lamellae; to the first approximation. length is a satisfactory indication of size. Length can therefore be used to predict the settling velocities of elements, and which elements will sort together. Measurement of element lengths allows a rapid estimation of the degree of post-mortem sorting undergone by a sample and therefore its suitability for use in palaeobiological analysis. □ Conodont hydrodynamics, biostratinomy, drag coefficient, settling velocity. sorting.     

Silurian bivalves

Liljedahl, L. 1994: Silurian nuculoid and modiomorphid bivalves from Sweden. Fossils and Strata 33 .     

Silurian scolecodonts

Bergman, Claes F. 1989: Silurian Paulinitid Polychaetes from Gotland. Fossils and Strata. No. 25.     

Toward an Ethnographic Language

In this article a general language for the characterization of ethnographic research is suggested. Drawing on interpretive philosophy, especially the work of Gadamer and Schutz, a core process of ethnography is described that emphasizes the resolution of problems in understanding across tradition boundaries. Concepts from recent work in knowledge representation are incorporated into the discussion to integrate it with current interdisciplinary work. [ethnography, hermeneutics, knowledge representation]