A Silurian radiolarian fauna based on 18 species is described from cherts from three sections in two quarries in the Sepon Mine area, central Laos. Each section contains distinctive assemblages but Futobari morishitai, F. solidus, Zadrappolus yoshikiensis and Z. tenuis are found in all three sections and are characteristic of the Ludlow–Pridoli Z. yoshikiensis Assemblage. In addition, the Hoei Yang pit section contains Zadrappolus hitoeganensis, Pseudospongoprunum sagittatum, Futobari sp. and Secuicollacta sp. Section CQ contains Pseudospongoprunum sagittatum, P. tazukawaensis, Praespongocoelia parva, P. sp., Rotasphaera sp. cf. R. quadrata, Secuicollacta sp. cf. cassa. Section QM also contains Pseudospongoprunum parvispina, P. sp., Zadrappolus sp. and Devoniglansus (?) seponensis new species Thassanapak is common. Evidence from Silurian and Devonian strata of the southern Truong Son Terrane indicates deepening towards the southern margin as defined by the Thakhek–Danang Shear Zone and exemplified by deep-marine Ludlow–Pridoli radiolarian cherts in the south, shallowing to fossiliferous, shallow-water sediments to widespread Old Red Sandstone type terrestrial facies 85 km further NE. The radiolarian cherts are in faulted contact with probable Llandovery limestone and Upper Ordovician – Llandovery graptolitic shales. The graptolitic shales are overlain with slight angular unconformity by the submarine fan, volcaniclastic-dominated, Namphuc Formation of Llandovery age. This fan received andesitic materials from the nearby Long Dai Volcanic Arc which extends eastwards to the Tamky Suture in Vietnam. This plutonic–volcanic arc was probably maintained by northwards subduction along the trend of the Permian–Recent Thakhek–Danang Shear Zone.

Brachiopods are among the most common components of the Late Ordovician benthic faunal assemblages recorded in the Faraghan Mountains, Zagros Ranges, Iran. A total of 19 species referable to 16 genera are identified, including seven new species; namely Drabovia elegans, Hibernodonta bonehensis, Hedstroemina zakeenensis, Jezercia faraghani, Protomendacella multicostata, Tafilaltia dargazensis and Tafilaltia seyahouensis. Reported brachiopod assemblages are oligotaxic (2–3 species per assemblage) to monotaxic. The only exception is the medium diversity Aegiromena-Hedstroemina Association, with up to ten species, which occurs at the lower part of the A. nigerica Zone. Low diversity patterns were probably controlled by the palaeogeographical position of the region in high southern latitudes throughout the Ordovician. Paterula sp. and Iranospirifer sp. are the only brachiopods documented from the Silurian (Llandovery) Sarchahan Formation. This paper gives the first detailed report of shelly fossils from the Llandovery ‘hot shale’ of the Arabian margin of Gondwana. Most of the Katian genera, and many of their species, are shared with neighbouring high- to mid-latitude peri-Gondwanan margins, including Morocco, Spain, France, Sardinia and Bohemia.

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.

Integrated graptolite, conodont and chitinozoan biostratigraphical data are presented from the Llandovery and Wenlock of the Kolka-54 core, Latvia. Correlations between graptolite and chitinozoan biozones are consistent with those published from other East Baltic sections and the Welsh Basin. While most correlations between graptolite and conodont biozones agree with those presented in previous studies, there are important exceptions. Significantly, we report here the discovery of Distomodus staurognathoides Biozone conodonts in the lowest Aeronian Demirastrites triangulatus graptolite Biozone. The base of the D. staurognathoides Biozone was previously considered to lie much higher in the Aeronian. Also it is shown that Walliserodus survived the late Wenlock Mulde Event, during which it was considered previously to have become extinct.

Though little is known of the graptoloid reproductive mechanism, graptolites with putatively sac-like appendages, supposedly ovarian vesicles, have been known from the Moffat Shales Group, Southern Uplands, Scotland, for over 150 years. Locally, these co-occur with isolated, two-dimensional, discoidal or ovato-triangular fossils. In the 1870s, Nicholson interpreted these isolated fossils as being graptoloid ‘egg-sacs’ detached from their parent and existing as free-swimming bodies. He assigned them to his genus Dawsonia, though the name was pre-occupied by a trilobite, and named four species: D. campanulata, D. acuminata, D. rotunda and D. tenuistriata. A reassessment of Nicholson’s type material from the Silurian of Moffatdale, Scotland, and from the Ordovician Lévis Formation of Quebec, Canada, shows that Dawsonia Nicholson comprises the inarticulate brachiopods Acrosaccus? rotundus, Paterula? tenuistriata and Discotreta cf. levisensis, the tail-piece of the crustacean Caryocaris acuminata and the problematic fossil D. campanulata. Though D. campanulata resembles sac-like graptolite appendages, morphometric analysis reveals the similarity to be superficial and the systematic position of this taxon remains uncertain. There is no definite evidence of either D. campanulata or sac-like graptoloid appendages having had a reproductive function.

The newly recognized Nant Brianne turbidite system was a focus of laterally supplied coarse-grade sediment deposition that, along with the Caban–Ystrad Meurig system, punctuated late Hirnantian to early Telychian, mudstone-dominated slope apron deposition along the SE margin of the southern Welsh Basin. Geological mapping coupled with detailed biostratigraphy enable the depositional influence of sea-floor topography, an active Llyn Brianne Fault and eustatic sea-level changes to be tracked. The latter may represent ‘far field’ effects relating to the retreat and advance of contemporary Gondwanan ice sheets. Slope apron mudstone facies reveal a strong response to high order eustatic events; however, the response of contemporary, easterly sourced, coarse-grade turbidite systems was more complex, with some periods of increased sand and gravel input coinciding with times of rising global sea level. These anomalous relationships are explained by invoking a series of smaller-scale movements in marine base level. It was the interaction of these lower order events with the main eustatic cycles that appears to have been the primary control on sand and gravel input to the Welsh Basin. An early Telychian expansion of the Nant Brianne turbidite system records a marked increase in tectonically generated sediment at a time of palaeo-plate collision between Baltica/Avalonia and Laurentia before intra- and peri-basinal faulting led to its abandonment as a supply path to the basin centre.

Forty-one Lower Silurian brachiopods from a single locality in the Newlands Formation of Girvan, Strathclyde, Scotland, are described and illustrated, many for the first time. The age of the fauna is well constrained by overlying magnus Biozone graptolites and underlying cyphus Biozone graptolites, indicating the early Middle Llandovery (Lower Aeronian) and it is the only shelly fauna known of Lower Aeronian age from anywhere in Scotland. A new endemic genus Chronostrophonella (Family Strophonellidae) is described: another new genus, Eopentamerus (Family Pentameridae) is known additionally from Wales. New species are Craniops laurentia, Biparetis caledonia, Eostropheodonta augusta, Chronostrophonella terranova, Strophochonetes newlandensis, Triplesia girvanensis, Resserella praeclara, Camerella? elainae, Eopentamerus inexpectatus and Protatrypa copperi. The Strophochonetes is the earliest-known chonetoid from the Silurian anywhere, although the family originated in the Late Ordovician. Whilst Newlands was on the margin of Laurentia just prior to its Caledonian Orogeny collision in mid-Silurian times with Avalonia–Baltica, the brachiopod fauna there was already similar in the Lower Aeronian, at least at the generic level, to those from the opposite side of the Iapetus Ocean in Wales and the Welsh Borderland (Avalonia) and Norway and other parts of Baltica. The proximity of these and other terranes to each other was the key reason for the relative cosmopolitanism of all lower-latitude Lower Silurian brachiopod faunas.

δ13Corg and TOC data are presented from the upper spiralis Biozone (Telychian, Llandovery, Silurian) through to the upper Sheinwoodian (Wenlock, Silurian) of the Banwy River section, Wales. In laminated hemipelagites from the Telychian, δ13Corg values rise through the upper lapworthi Biozone to a maximum in the lower insectus Biozone after which they decline slightly. The most conspicuous feature of the δ13Corg curve is the prolonged positive excursion in the Sheinwoodian, commencing in the upper murchisoni Biozone and ending in strata yielding Monograptus flexilis. This Sheinwoodian positive δ13C excursion in the Banwy River section correlates precisely with that recognized in the East Baltic. The interval with the highest δ13Corg values also records the highest TOC values, suggesting that for the Sheinwoodian at least burial of carbon may have contributed to the positive δ13C excursion. Bioturbated strata yield very low TOC values; whether the δ13Corg values from these beds reflect a primary signal or the result of biostratinomic or diagenetic modification is uncertain.

Earliest Silurian (basal Llandovery) brachiopod faunas are surveyed and listed from around the globe, and divided between Lower Rhuddanian and Upper Rhuddanian occurrences. 60 genera are known from the Lower Rhuddanian within 20 superfamilies and there are 87 genera in 25 superfamilies in the Upper Rhuddanian. The 29 areas surveyed span the globe, both latitudinally and longitudinally. Only six superfamilies are Lazarus taxa which are known both from the Ordovician and Middle Llandovery (Aeronian) and later rocks but have not been recorded from the Rhuddanian. These are surprising results, since many previous studies have inferred that the Rhuddanian was a time of very sparse faunas. The global warming that followed the latest Ordovician (Hirnantian) ice age did not proceed quickly, with an ice-cap probably present through at least the Llandovery. There is a marked absence of Lower Rhuddanian bioherms even at low palaeolatitudes; however, the ecological recovery rate was far faster than that following the end-Permian mass extinction event. The partitioning of the Rhuddanian shelf faunas into well-defined benthic assemblages progressed slowly over the interval.

The lower Williamson Shale at Tryon Park, Rochester, New York State is unique in the co-occurrence of Stimulograptus clintonensis (Hall), previously recorded only from the middle Telychian, and Pterospathodus amorphognathoides amorphognathoides Walliser, previously recorded only from the upper Telychian (Cyrtograptus lapworthi Biozone and higher). These two co-occurring fossils are clearly providing contradictory ages for the lower Williamson Shale. The incorporation of chitinozoan data from both the Williamson and Willowvale shales does not support unequivocally either the graptolite- or conodont-derived biostratigraphy and thus the age of the lower Williamson Shale remains problematical.

Integrated graptolite and chitinozoan biostratigraphical data are presented from the upper Telychian (Oktavites spiralis and Cyrtograptus lapworthi graptolite biozones) of the Ventspils D-3 core, Latvia. The base of the Angochitina longicollis chitinozoan Biozone is approximately coincident with that of the spiralis graptolite Biozone, as it is elsewhere in the East Baltic, although in Wales it lies within the upper spiralis graptolite Biozone. Conochitina proboscifera appears in the upper spiralis graptolite Biozone in the Ventspils D-3 core, but at lower and higher horizons elsewhere, presumably reflecting its patchy distribution during the lower part of its stratigraphical range. Ramochitina ruhnuensis appears to be a stratigraphically useful, although geographically restricted, species, appearing at a level close to the base of the lapworthi graptolite Biozone. The most remarkable feature of the Ventspils D-3 chitinozoan record is the very early occurrence, in the upper spiralis graptolite Biozone, of two chitinozoan biozonal index species: Margachitina banwyensis and M. margaritana. Previously, these two taxa were considered unequivocal indicators of the uppermost Telychian to Sheinwoodian or Homerian, respectively.

The Silurian arthropod Bembicosoma pomphicus Laurie, 1899 is re-studied in relation to other Palaeozoic chelicerate taxa. All three known specimens of Bembicosoma originate from the Silurian (late Llandovery) Eurypterid Bed of the Gutterford Burn Flagstones, Reservoir Formation, Pentland Hills, Scotland. Bembicosoma is removed from its previous tentative assignment to Eurypterida and re-assigned to Xiphosura. A morphological reconstruction of this taxon is presented for the first time. This work continues a reappraisal of the systematics of a number of taxa that belong within the synziphosurines, a loose grouping of early Palaeozoic chelicerate arthropods aligned with the Xiphosura (horseshoe crabs), but which have been mistakenly identified as eurypterids in the past. Bembicosoma is significant as it is one of the earliest known synziphosurines.

Forty-six samples, taken from the Upper Ordovician and lower Silurian strata of the Girvan district, Midland Valley of Scotland, yield moderately well-preserved and diverse assemblages of chitinozoans. The area was chosen to study the composition of the chitinozoan assemblages, rarely described before in Scotland, which lay at the south-eastern margin of the Laurentia palaeocontinent. These assemblages are compared with those of the same age on other palaeocontinents, representing a critical time when both the Iapetus and Tornquist oceans were closing, thus forming the Caledonide and associated orogens. It is possible to correlate the chitinozoan occurrences at Girvan with those of other parts of Laurentia (Quebec area), other palaeocontinents such as Baltoscandia (Sweden, Estonia), Avalonia (Wales, Brabant Massif) and some parts of Northern Gondwana (Saudi Arabia). For the lower Silurian, it is possible to correlate with the global chitinozoan biozonation, and a calibration between the chitinozoan occurrences and the graptolite biozonation of Girvan is established. Several levels within the Balclatchie, South Shore, Three Mile, Shalloch, Wood Burn, Lauchlan, Drumyork Flags and other formations are accurately dated.