Abstract A variety of unrelated organisms produce agglutinated tubes as dwelling structures, and the habit has persisted since the Neoproterozoic. Onuphionella , an agglutinated tube composed of mica flakes, has been found in lower Cambrian strata on several palaeocontinents. In this paper, a new species of the genus, Onuphionella corusca sp. nov., is described from the Sandbian (Upper Ordovician) First Bani Group of the Erfoud region, Morocco. The First Bani Group was formed in a storm-dominated shelf environment below fair-weather wave base. The agglutinated tubes are found in abundance on numerous bedding surfaces, possibly representing repeated colonization between storm events, and the tube maker must have been a major part of the local ecosystem. This is the first report of Onuphionella from Ordovician rocks and the first from Gondwana. Supplementary material: Data tables for major oxide and trace element results are available at https://doi.org/10.6084/m9.figshare.c.4283612

Abstract The crinoid fauna of the Late Ordovician (Sandbian and Katian) of Morocco is sparse, but diverse. The one previously described species, Rosfacrinus robustus Le Menn & Spjeldnaes, 1996 , is now known to be part of an assemblage of at least 10 species, including the new taxa Iocrinus ouzammoui sp. nov. (Disparida), Superlininicrinus advorsa gen. et sp. nov., Isthloucrinus praecursor gen. et a sp. nov. (Cladida) and Euptychocrinus ? atelis sp. nov. (Camerata). The fauna also includes an additional species of Iocrinus , and several camerates including Trichinocrinus sp. and a monobathrid with probable affinities to the Tanaocrinidae. Undeterminable specimens of demonstrably different taxa are described as far as possible. The fauna includes genera previously known from Laurentia and Avalonia, implying unexpected latitudinal dispersal, together with evidence for substantial endemic diversification among cladids and camerates. Several of the taxa have unusual plate arrangements, including a mosaic of primitive and derived characters; this implies that early crinoid diversification was not limited to tropical carbonate facies. The fauna remains poorly known, with low numbers of specimens, and future collecting is likely to increase the diversity significantly.

Abstract The Cambrian, Ordovician and Silurian distributions of non-stromatoporoid sponges are reviewed. The earliest Cambrian faunas contain mostly hexactinellids, with protomonaxonids dominating middle Cambrian assemblages. There are no obvious palaeobiogeographical patterns, with many genera being found widely. Vauxiids, lithistids and heteractinids are apparently confined to low latitudes, but this may be due to a poor fossil record. Most known Ordovician faunas are from low latitudes, although some high-latitude faunas are known, which contain reticulosan hexactinellids and protomonaxonids. There is some division of faunas within Laurentia, into eastern and western provinces, with the western assemblage extending across low northern latitudes during the Late Ordovician. During the Silurian Period, sponge diversity was very low during the Llandovery Epoch, probably partly owing to lack of habitat for taxa restricted to carbonate facies, and also because of sampling bias. There was a dramatic increase in diversity through the Silurian Period, mostly owing to an apparent diversification in the demosponges; however, there are many ghost lineages, indicating that their fossil record is poorly known. Non-lithistid sponges are very poorly known, with few recorded outside Euramerica. The currently available data for Early Palaeozoic sponges are too incomplete to allow any reliable palaeobiogeographical inferences. Supplementary material: the compilation of Silurian sponge occurrences is available at: http://www.geolsoc.org.uk/SUP18666 .

Abstract Pyroclastic volcanism has been tentatively correlated with Ordovician faunal diversification, but it is unclear whether the volcanism itself or associated tectonic effects were more influential. Elevated nutrient flux from uplifted areas has been widely discussed, but the link between enhanced productivity and diversification is unclear. Ecosystem com-partmentalization due to irregular topography was probably significant, but it is debatable whether this was sufficient to explain the entire diversification. This paper introduces a further volcanic process, which may have been more significant than these established hypotheses, although it is emphasized that all relevant factors acted in combination. Recent studies of the local ecological effects of ash-fall have revealed dramatic post-depositional plankton and benthic blooms associated with overturning of a stratified water mass. The data are consistent through all studied sections from the Builth Inlier, Central Wales, while deeper-water sediments showed plankton blooms only. Repeated bloom events over localized dysaerobic shelf areas may have produced temporary benthic ‘islands‘, enhanced genetic heterogeneity within affected regions, and increased speciation rates. In order to maximize bloom intensity (and possible effects on evolution), this process requires widespread pyroclastic volcanism combined with extensive shelf areas with well-developed stratification. The hypothesis potentially allows explanation of the differential rates of evolution between different groups, particularly the decoupled planktic-benthic patterns. A preliminary test using Welsh Basin ostracodes is presented, with predictions for the global database results.