The tubarium construction in Holoretiolites, Neogothograptus and related taxa (Graptolithina, Retiolitinae): clues to their astogeny and species identification

The Homerian (Wenlock) to Ludfordian (Ludlow), late Silurian, retiolitine genera Neogothograptus and Holoretiolites and their relatives are revised. These are often considered as the youngest and smallest retiolitine taxa, characterised by a finite growth indicated by the appendix, leading to the extinction of the clade. The tubarium construction of the genera is analysed and compared, showing the loss of the pleural and parietal lists in Holoretiolites and the development of a central zigzag construction on the obverse and reverse sides of the tubarium. This construction is not homologous to similar constructions in earlier retiolitines, as it is based on the modification of the lateral apertural lists. It is also found in the closely related Semiplectograptus and Plectodinemagraptus. Useful details to understand the astogeny of these taxa include the development of the reticulum, the genicular processes and the outer ancora. These features are described for the first time for most species. Details of the outer ancora and its construction in the genus Neogothograptus are still poorly understood. Holoretiolites helenaewitoldi is synonymised with Holoretiolites atrabecularis. Holoretiolites manckoides is transferred to Semiplectograptus

Silurian stratigraphy and graptolite faunas of the Mora 001 and Solberga 1 drill cores, Siljan District, central Sweden

The Mora 001 and Solberga 1 drill cores provide the best available overview on the early Silurian (Llandovery, Rhuddanian to Telychian) graptolite succession available for the Siljan Ring impact structure of central Sweden. The Solberga 1 succession includes a nearly complete graptolite succession from the Pernerograptus revolutus Biozone (late Rhuddanian) to the Oktavites spiralis Biozone (late Telychian). Older graptolite faunas are unknown from the Siljan region. The Mora 001 drill core includes a graptolitic succession from the Monoclimacis crenulata Biozone to the O. spiralis Biozone, found in two lithostratigraphically separated lithological units here identified as the Kallholn Formation. A slice of the Orsa Sandstone Formation of possible later Silurian age is tectonically introduced into the Kallholn Formation in the Mora 001 drill core. The strong tectonic deformation of the Kallholn Formation in both drill cores can easily be understood through the Devonian impact history of the region

Retiolitid graptolites from the collection of Hermann Jaeger III. Paraplectograptus, Gothograptus and their relatives

The graptolite collection of Hermann Jaeger at the Museum für Naturkunde in Berlin, Germany includes a number of Paraplectograptus and Gothograptus specimens. The material provides another glimpse into the dramatic changes affecting retiolitine graptoloids across the Lundgreni Extinction Event of the mid Homerian (Wenlock, Silurian) which led to the demise of most earlier groups of retiolitines. The material indicates that the diversity of the pre-extinction retiolitines might have been larger than is already known through the recognition of previously unknown constructional details in earlier Gothograptus and Paraplectograptus species. Especially, Gothograptus shows a much higher diversity in the pre-extinction interval than previously recognized. In the Pristiograptus parvus/Gothograptus nassa Biozone interval Gothograptus re-emerged with new species and Semigothograptus is shown to have survived unchanged, indicating that these two genera represent survivors of the extinction event. A number of new genera originated and diversified in the Pristiograptus dubius/Gothograptus nassa to Colonograptus praedeubeli/deubeli Biozone interval, but their evolutionary relationships with earlier taxa are still only partly understood. Paraplectograptus hermanni sp. nov., Gothograptus berolinensis sp. nov. and Gothograptus osgaleae sp. nov. are described as new. Several species are described in open nomenclature due to the lack of sufficiently well preserved material

Industrial Resources - Fulton County - Hickman

Resources for Economic Development: Hickman, Kentucky” prepared by the Kentucky Department of Economic Development, Division of Research and Planning, and the Purchase Area Development District, 1985. The report includes, but is not limited to, information about: population, labor market, local manufacturing, transportation, utilities, fuel, water, sewage, industrial sites, local government and services, taxes, educational and health facilities, housing, communication, recreation, natural resources, markets, and climate

Silurian graptolite biostratigraphy of the Röstånga-1 drill core, Scania:a standard for southern Scandinavia

The Rostanga-1 core from west-central Scania provides the most complete succession of the Sandbian (Upper Ordovician) through lower Telychian (Silurian, Llandovery) strata of southern Scandinavia. The Hirnantian is identified in the Kallholn Formation by the presence of a Metabolograptus persculptus Biozone fauna. The Akidograptus ascensus, Parakidograptus acuminatus, Cystograptus vesiculosus and Monograptus revolutus biozones can be differentiated in the Rhuddanian. Following a considerable gap (Demirastrites triangulatus Biozone to a level within the Pribylograptus leptotheca Biozone), the succession resumes. The Aeronian also includes the Lituigraptus convolutus and Stimulograptus sedgwickii biozones. The Stimulograptus halli Biozone appears to be missing, but the Telychian Spirograptus guerichi to Streptograptus crispus biozones have been recognized

What is Diplograptus?

Diplograptus pristis (Hisinger, 1837) is the type species of the genus Diplograptus and name bearer for suborder Diplograptina. This species is primarily known from the Dalarne region of Sweden, where it occurs in the P. linearis Zone. D. pristis exhibits a suite of features (particularly the shape of the proximal end, the configuration of proximal spines, and the gradient in thecal form) that is uniquely shared with a number of other late Katian and earliest Hirnantian species including Glyptograptus nicholsoni Toghill, 1970; Glyptograptus posterus Koren’ & Tzai (in Apollonov et al. 1980); Orthograptus maximus Mu, 1945; and Orthograptus truncatus rarithecatus Ross & Berry, 1963. The phylogenetic affinities of the Diplograptus clade are equivocal, however. Two isolated, three-dimensionally preserved specimens of D. pristis from the Paasvere 309 core in Estonia reveal that the rhabdosome is aseptate and has a simple proximal structure comparable with a Pattern G astogeny. The pattern G astogeny, long, fully-sclerotized sicula, aseptate rhabdosome with free nema all point to its being a member of the derived orthograptids. On the other hand, the rapidly enclosed sicula and lack of antivirgellar spines together with the apertural spines on the first pair suggest archiclimacograptid affinity. Cladistic analysis supports orthograptid affinities. If these relations are correct, the Orthograptidae Mitchell, 1987, must be regarded as a junior synonym of the Diplograptidae Lapworth, 1873

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

Rock specimens and contained fossils collected in 1976 from a submarine tunnel driven between Herøya and Rafnes in the Skien–Langesund area of southern Norway, have been restudied. The contained fossils include olenid and agnostoid trilobites, graptolites and brachiopods, groups described in detail for the first time from the area and documenting a Cambrian–Ordovician boundary section unique in the district where the upper Cambrian Alum Shale Formation is elsewhere overlain by the Middle Ordovician Rognstranda Member of the Huk Formation (Kundan in terms of Baltoscandian chronostratigraphy). The hiatus at the base of the Huk Formation is thus smaller in the section described herein, beginning at a level within rather than below the Tremadocian. Estimated thickness of the Alum Shale includes 10–12 m of Miaolingian and 20–22 m of Furongian strata with trilobite zones identified, and a Tremadocian section of 8.1 m identified by species of the dendroid graptolite Rhabdinopora in the basal 2.6 m and Bryograptus ramosus at the top. The Tremadocian section is preserved in a postulated zone of synsedimentary subsidence along the Porsgrunn–Kristiansand Fault Zone, while at the same time there was extensive erosion across an emergent, level platform elsewhere in the Skien–Langesund District and the southern part of the Eiker–Sandsvær District to the north. Aspects of stratigraphy and tectonics are highlighted together with a discussion on the Cambrian– Ordovician boundary locally and worldwide

The Xiaoyangqiao section, Dayangcha, North China: the new global Auxiliary Boundary Stratotype Section and Point (ASSP) for the base of the Ordovician System

In 2019 the Sub-Commission on the Ordovician System approved the Xiaoyangqiao section, North China as a new ASSP section for the base of the Ordovician System. The sedimentary succession of the section is exposed in a natural outcrop near the Dayangcha Village at a position of 42°3'24''N, 126°42'21''E. It has a well-preserved, abundant and diverse fossil record across the boundary with key markers (conodonts and graptolites), which provide improved intercontinental correlation of the Cambrian– Ordovician boundary. The appearance of the first planktonic graptolites is immediately below the base of the Cordylodus lindstromi Conodont Zone. Other fossils, including acritarchs, brachiopods and trilobites are also present in the Xiaoyangqiao ASSP section. Non-biotic secondary global markers near the base of the Ordovician System include a positive carbon isotopic excursion with the maximum peak (named HSS) below the boundary, a prominent unnamed negative peak immediately below the boundary and a prominent carbon isotope excursion with positive peaks above the boundary. The latter excursion is associated with the appearance of the planktonic graptolites in the Ordovician. The strength of the Xiaoyangqiao ASSP section is the correlation between the conodonts and graptolites, correspondence of sea-level lowstands, and the matches of geochemical parameters

Devonian and Carboniferous dendroid graptolites from Belgium and their significance for the taxonomy of the Dendroidea

peer reviewedDevonian and Carboniferous dendroid graptolites from Belgium are evaluated and partly revised. New finds in two different stratigraphic intervals of the ‘Carrière de Lompret’, an active quarry exploiting Frasnian limestones and shales east of Frasnes-lez-Couvin, allow the identification of Callograptus sp. and Dictyonema fraiponti, both belonging to the dendroid family Acanthograptidae. The relatively high diversity of the dendroid graptolite fauna from the Viséan Marbre noir de Denée, one of the few Carboniferous graptolite faunas in the world, can be shown to be based on astogenetic and preservational aspects. Nearly all known specimens can be included in the highly variable Dictyonema fraiponti, a fan-shaped large dendroid species with complex stipes formed from tubular thecae, possessing simple to complex bridges connecting adjacent stipes. Some of the graptolite material is well preserved and provides important information on the tubarium construction of Devonian to Carboniferous dendroid graptolites and, thus, is highly significant for a taxonomic and phylogenetic understanding of the youngest dendroid graptolite faunas worldwide. The genera Callograptus and Ptiograptus are revised based on their type species (Callograptus elegans from Quebec, Canada; Ptiograptus percorrugatus from the Silurian or Devonian of Kentucky, USA) and referred to the Acanthograptidae