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The Arenig Fawr area of North Wales constitutes the type area for the British Lower to Middle Ordovician Arenig Series and is complemented by sections in the Carmarthen and Whitland areas of South Wales. We describe chitinozoan assemblages from both areas in order to aid correlation of the Arenig Series in its type region with the global Ordovician series and stages. Chitinozoans recorded from Arenig Fawr provide permissive rather than conclusive evidence but suggest that the Henllan Ash Member correlates with the upper Floian Stage Slice Fl3 or lower Dapingian Stage Slice Dp1. Better results were obtained from South Wales where six chitinozoan assemblages are distinguished, ranging in age from late Tremadocian to middle Darriwilian (early Llanvirn). Most species are known from South China, Gondwana and/or Baltica where there are controls on ranges. They show that much of the lower Arenig (Moridunian) succession in South Wales correlates with the upper Floian Stage (Fl3). Correlatives of the lower and middle Floian Stage (Fl1, Fl2), if present, must be represented by the Ogof Hên Formation and lowest Carmarthen Formation. Chitinozoan assemblages from the upper Arenig Series (Fennian Stage) are more readily correlated with Gondwanan biozones and indicate correlation of the Fennian Stage with the Dapingian and lower Darriwilian (Dw1) stages. The middle Arenig Whitlandian Stage is constrained in South Wales to an interval from the uppermost Floian Stage to the basal Dapingian Stage, resulting in an inferred increased rate of sediment accumulation. [ABSTRACT FROM AUTHOR]

We examine three distinctive biostratigraphic signatures of humans associated with hunting and gathering, landscape domestication and globalization. All three signatures have significant fossil records of regional importance that can be correlated inter‐regionally and help describe the developing pattern of human expansion and appropriation of resources. While none have individual first or last appearances that provide a globally isochronous marker, all three signatures overlap stratigraphically, in that they are part of a continuum of change, with complex regional patterns. Here we show that during the later stages of globalization, late nineteenth to twentieth century records of species translocations can be used to build an interconnected web of palaeontological correlation with decadal or sub‐decadal precision that dovetails with other stratigraphic markers for the Anthropocene. This palaeontological web is also a proxy for accelerating species extinction and of a state shift in the biosphere in the twentieth century. [ABSTRACT FROM AUTHOR]

Profound changes to the species configuration of ecosystems globally during the 19th to 21st centuries, resulting from the introduction of neobiota, have produced a distinctive palaeontological signature in sedimentary deposits, here exemplified by those of the River Thames. Coring near Teddington Lock (ca. 4.3 m above sea level, ca. 89 km upstream from the mouth of the Thames estuary) yielded dense assemblages of shells of the invasive Asian clam Corbicula fluminea (recently invaded in 2004) and the zebra mussel Dreissena polymorpha (invaded 1824), which together accounted for 96% of individuals sampled. Population densities of C. fluminea of over 6000 individuals per m2 were maintained for a depth of 1 m indicating that the Asian clam is an important biostratigraphical marker in the Thames for sedimentary deposits accumulating since 2004. The first modern European occurrence of C. fluminea was in Portugal in 1980. In 1987, the first occurrence of C. fluminea on the northern coast of South America was observed in the Caripe River, Venezuela. The non‐native range of D. polymorpha was restricted to continental Europe for over 200 years until it appeared in the Great Lakes, USA, in 1986 having been transported in ballast water. Within three years, it reached populations of over 750,000 individuals per m2 and it is presently recorded in 35 states. Therefore, the pan‐Atlantic range expansion of D. polymorpha, coupled with the recent invasion history of C. fluminea in Venezuela and Portugal, identifies a biostratigraphical interval in sedimentary deposits forming from the early 1980s that can be correlated between Europe and the Americas. [ABSTRACT FROM AUTHOR]

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Systematic collecting through the upper Wenlock (upper Homerian) and lower Ludlow (Gorstian and lowermost Ludfordian) Silurian rock succession of the Long Mountain, Powys, Wales, identifies some 48 chitinozoan species that distinguish four biozones, two subzones and an interregnum. Consideration of the chitinozoan biozones together with those of the graptolites enables a local three-fold subdivision of the late Homerian lundgreni graptolite Biozone, and the distinction of lower and upper intervals for the Gorstian incipiens graptolite Biozone. The base of the Ludlow Series in the Long Mountain more or less equates to the base of the Cingulochitina acme chitinozoan Biozone, although no key chitinozoan first or last appearance datums are associated with the series boundary itself. The new graptolite–chitinozoan biozonation allows enhanced correlation between upper Wenlock and lower Ludlow sedimentary deposits of the Lower Palaeozoic Welsh depositional basin and those of the palaeo-shelf in the stratotype Wenlock and Ludlow areas of Shropshire. Chitinozoans seem affected by the phenomena that caused the late Wenlock ‘Mulde extinction’ in graptolites but, with the final disappearance of 9 species and re-appearance of 11 species following an interval of overall low diversity, they seem to have suffered less severely than their macro-zooplanktonic contemporaries. [ABSTRACT FROM AUTHOR]

The global standard for the Llandovery Series (early Silurian) in central Wales is re-assessed in the light of detailed geological surveying, biostratigraphical sampling and a rigorous examination of published datasets. A new sedimentary and biostratigraphical architecture is presented. Key graptolite, brachiopod, acritarch and, for the first time, chitinozoan assemblages are critically assessed. Upper Hirnantian to Aeronian strata record events that followed the Late Ordovician glacial maximum and comprise a series of progradational sequences bounded by flooding surfaces, but inferred still to be glacioeustatic in origin. Significant faunal renewals associated with many of the flooding levels underpin their potential for international recognition. Compound non-sequences are a feature of proximal parts of the system where erosion associated with fault footwall uplift was an important process. Extensive slump sheets contribute to further stratal loss and displacement in distal facies. A re-assessment of the Aeronian Stage GSSP reveals shortcomings with the biostratigraphical criteria used in its selection. Telychian portions of the succession display the disrupting effects of intra-Wenlock synsedimentary sliding; hence the relevance of key published fossil assemblages and the criteria used to erect the stage GSSP are undermined. However, the Llandovery area remains one of the best studied early Silurian successions in the world. This, together with regional considerations, supports the retention of the series standard in mid Wales where the contiguous deep-water basinal succession affords internationally cited exposure of richly graptolitic facies for the whole series and, significantly, for the post-sedgwickii Biozone interval. [ABSTRACT FROM AUTHOR]

To help calibrate the emerging Upper Ordovician chitinozoan biozonation with the graptolite biozonation in the Anglo-Welsh, historical type basin, the graptolite-bearing Caradoc-Ashgill successions between Fishguard and Cardigan, and at Whitland, SW Wales, have been collected for chitinozoans. In the Cardigan district, finds of Armoricochitina reticulifera within strata referred to the clingani graptolite Biozone (morrisi Subzone), together with accessory species, indicate the Fungochitina spinifera chitinozoan Biozone, known from several Ordovician sections in northern England that span the base of the Ashgill Series. Tanuchitina ?bergstroemi, eponymous of the succeeding chitinozoan biozone, has tentatively been recovered from strata of Pleurograptus linearis graptolite Biozone age in the Cardigan area. The T. ?bergstroemi Biozone can also be correlated with the type Ashgill Series of northern England. Chitinozoans suggest that the widespread Welsh Basin anoxic-oxic transition at the base of the Nantmel Mudstones Formation in Wales, traditionally equated with the Caradoc-Ashgill boundary, is of Cautleyan (or younger Ashgill) age in the Cardigan area. In the broadly time-equivalent, graptolite-rich Whitland section, also in SW Wales, two Baltoscandian chitinozoan biozones and a subzone have been recognized (again using accessory species), namely the Spinachitina cervicornis Biozone?, the Fungochitina spinifera Biozone and the Armoricochitina reticulifera Subzone. The new chitinozoan data provide a more precise means of correlation between the Whitland and Cardigan successions and suggest that the Normalograptus proliferation interval of the Whitland section is at least partly attributable to the Dicellograptus morrisi Subzone of the Dicranograptus clingani Biozone, rather than equating with the overlying Pleurograptus linearis Biozone. [ABSTRACT FROM AUTHOR]

The Wenlock sequence of the Builth Wells district, central Wales is dominated by long-ranging Monograptus, Pristiograptus and Monoclimacis species. Cyrtograptus species, which underpin the graptolite biozonation, represent only about 10 per cent of recovered individuals. Ten Cyrtograptus species are present, most being zonal index species for the Builth district or other Wenlock sequences. Redescription of these Cyrtograptus species and comparison with all pertinent type material indicates that: the early Wenlock Cyrtograptus insectus, C. centrifugus and C. murchisoni are best distinguished by means of first whorl diameter, sicula length and differences of cladial development; mid Wenlock Cyrtograptus rigidus may bear a secondary cladium, but at Builth there are no stratigraphically discrete subspecies; Cyrtograptus linnarssoni is known only from its type locality; the long, gracile proximal part of the rhabdosome of C. ellesae facilitates its distinction from C. perneri, with which it has been confused, and indicates similarities to C. ramosus and C. lundgreni. Differences in the ranges of key Cyrtograptus species present problems for correlation between the lundgreni Biozone of the Builth district and the perneri-ramosus and lundgreni biozones of central Europe. The low diversity and abundance of the cyrtograptid fauna of the Builth district, compared to those of Arctic Canada and the Czech Republic, suggests relatively inhospitable conditions for graptolites. [ABSTRACT FROM AUTHOR]

New stable isotope data from organic carbon (δ 13 C org ) and inorganic elemental geochemistry data have been generated from Upper Ordovician to Silurian strata in two boreholes in the Lublin Basin of Poland: Grabowiec-6 and Zwierzyniec-1. They have been integrated here with biostratigraphical data from graptolites, acritarchs, and chitinozoans. Faunal assemblages from Grabowiec-6 indicate that it spans from the Katian ( clingani graptolite Biozone) to the Gorstian ( scanicus graptolite Biozone); δ 13 C org values from this section record the Sheinwoodian Ireviken Excursion, the Homerian Mulde Excursion, and a minor positive shift associated with the lower Ludfordian leintwardinensis Biozone. The second section, Zwierzyniec-1, spans the Sandbian through Gorstian ( nilssoni Biozone); δ 13 C org values record the Hirnantian carbon isotope excursion (HICE) and the Ireviken Excursion as well. Elemental geochemistry data is used to recognize subtle changes in provenance and lithology. Significant increases in the abundance of V and Mo are recognized in strata deposited above the Ireviken Excursion. The enrichment of these redox sensitive elements suggests that persistent regional anoxia and euxinia may be associated with the aftermath of these oceanographic disturbances. Some of these same trace elements, along with Fe 2 O 3 , and Pb are also abundant in strata coeval with, or just below the Ireviken and HICE excursions. This may have a causal link with malformed palynomorphs observed at these intervals by some workers, which are thought to reflect toxic levels of dissolved heavy metals in the world's oceans. [ABSTRACT FROM AUTHOR]

A numerically small graptolite assemblage from the Long Dai Formation at Lam Thuy village, southwestern Le Thuy district, Quang Binh Province, central Vietnam, includes Oktavites spiralis (Geinitz). The relative abundance of this species in the assemblage, coupled to its occurrence with Oktavites bodentoerlensis Loydell, identifies the lower Silurian (Llandovery Series, Telychian Stage) spiralis graptolite Biozone. Identification of the new locality at Lam Thuy enhances the dataset of Silurian graptolite-bearing localities in central Vietnam and advertises the wide utility of graptolite assemblages for biostratigraphical correlation of lower Palaeozoic strata in northern and central Vietnam. [ABSTRACT FROM AUTHOR]

The early Silurian (Llandovery) Gondwanan South Polar ice sheet experienced episodes of ice retreat and re-advance. Marine base level curves constructed for the interval are widely assumed to provide a record of the associated glacioeustasy. In revealing a series of progradational sequences (progrades) bounded by flooding surfaces, recent work on the Type Llandovery succession in mid Wales (UK) has provided an opportunity to test this hypothesis. The grouping of these progrades into three composite sequences underpins the construction of both low order (small amplitude, high frequency) and high order (large amplitude, low frequency) base level movement curves. Revised biostratigraphical datasets for the type succession permit the accurate dating of base level events. The composite sequences record progradational acmes in the acinaces , lower convolutus and upper sedgwickii-halli graptolite biozones. A series of transgressions that postdate the Hirnantian glacial maximum culminated in an upper persculptus Biozone high-stand. Maximum flooding events also occurred during the revolutus and lower sedgwickii biozones, and the base of the early Telychian guerichi Biozone also marked the onset of a pronounced deepening. A review of 62 published datasets, including global and other regional base level curves, records of glacial activity, isotope data, patterns of facies and faunal flux and putative climate models, permits an evaluation of the origins of these local base level events. The concept of a Eustasy Index is introduced and shows that the impacts of global sea level movements can only be demonstrated within narrow ‘eustatic windows’ coincident with times of ice sheet collapse. At other times, the geometry of Llandovery area progrades reflects their accumulation across a faulted basin margin where, during periods of slow ice sheet advance, epeirogenic processes outstripped sea level movements as the dominant forcing factors. Increased levels of Telychian subsidence at first enhanced and then overwhelmed the influence of glacioeustasy as part of the region's response to the north European Scandian deformation. [ABSTRACT FROM AUTHOR]

Sixty one core samples from three shallow core holes (Qusaiba-1, Baq'a-3 and Baq'a-4) penetrating the Qalibah Formation (Qusaiba Member) in the North Central Saudi Arabia were investigated. These core slabs corresponding to grey–greenish hemipelagic shale or silty-shale yield well-preserved and very abundant early Silurian chitinozoans. Most of the recorded chitinozoan assemblages are diverse and include several new species occurring with well-known species. An informal early Rhuddanian chitinozoan assemblage dominated by Cyathochitina caputoi is documented in the lowermost part of the Qusaiba Member. The six chitinozoan biozones defined above this basal assemblage range from Aeronian to Telychian. They are considered of regional value for northern Gondwana. From the lowest to the highest they are the Angochitina qusaibaensis (pro parte), Conochitina alargada , Angochitina hemeri , Angochitina macclurei , Tanuchitina obtusa and Euconochitina silurica biozones. The older regional biozones have been previously documented in Saudi Arabia whereas the two youngest ones, the eponymous index species of which were described from the subsurface of the Algerian Sahara, are documented for the first time in the Arabian Peninsula. Four subbiozones, of at least of regional application, are also defined in order to improve the precision of biostratigraphic correlation between Silurian lithostratigraphic units cropping out along the Arabian Shield and their counterparts in the subsurface of Central Saudi Arabia. Thanks to the closely spaced and to the regular sampling, the total range of several highly diagnostic forms as well as the interval of uncertainty between the successive chitinozoan biozones are better constrained. A hiatus with a duration of late Rhuddanian to early Aeronian separates the lowest informal chitinozoan assemblage from the qusaibaensis Biozone. A recent detailed study of the graptolites in the three cored holes provides independent chronostratigraphical control calibrating the previous chitinozoan-based age assignments. The qusaibaensis (pro parte), the alargada , and the hemeri chitinozoan biozones occur with the mid-Aeronian convolutus graptolite Biozone whereas the macclurei chitinozoan Biozone extends through the early Telychian guerichi and turriculatus graptolite biozones. The obtusa and the silurica chitinozoan biozones occur in an interval devoid of usable graptolites. They are referred to the mid–late Telychian as they do not contain typical Sheinwoodian species. Besides the abundant chitinozoans and acritarchs, sporadic occurrences of scolecodonts and of eurypterid cuticle fragments are also noted in the organic residues. The presence of eurypterids reflects a shallowing trend in the sedimentary record, which is consistent with the distribution of the graptolite remains (siculae and/or rhabdosomes). Indeed, graptolites are common throughout the Qusaiba Member, except in the youngest processed samples presaging the shallower environments prevalent in the Sharawra Member. The taphonomy of the chitinozoans (isolated vesicles, chain-like structures, clusters, coprolites) and their environmental context is briefly discussed. Fifteen new species are described and illustrated: Ancyrochitina alhajrii sp. nov., Ancyrochitina camilleae sp. nov., Armoricochitina crassicarinata sp. nov., Armoricochitina gengi sp. nov., Bursachitina baqaensis sp. nov., Conochitina viiuae sp. nov., Cutichitina minivelata sp. nov., Cyathochitina neolatipatagium sp. nov., Fungochitina merrelli sp. nov., Muscochitina olivieri sp. nov., Plectochitina alisawyiahensis sp. nov., Plectochitina alnaimi sp. nov., Plectochitina jaquelineae sp. nov., Plectochitina lucasi sp. nov., and Spinachitina geerti sp. nov. [ABSTRACT FROM AUTHOR]