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The Miocene Climatic Optimum (MCO, ~17-15 Ma) was a relatively warm interval that interrupted the Cenozoic cooling trend and bears analogies with projected end-of-the-century climate. Proxy data and model simulations indicate temperatures were on average ~7 – 8°C higher than present day and atmospheric pCO2 values were 500-600 ppmV. At high latitudes, upper ocean temperatures were ~10 – 15°C warmer than present day, but available tropical temperature records are limited. Importantly, to be able to use Miocene paleoclimate records to quantify key climate parameters like the polar amplification of climate change, accurate reconstructions of tropical surface oceans are required.We present high resolution Early to Middle Miocene (~15 – 18 Ma) records of tropical sea surface temperature (SST) variability based on the lipid biomarker paleothermometer TEX86 at Ocean Drilling Program (ODP) Site 959 in the eastern equatorial Atlantic Ocean and at ODP Site 1007 at Bahama Bank in the western tropical Atlantic Ocean. The age model for both sites is based on chemo- and biostratigraphy. Moreover, analyses of bulk carbonate oxygen- (δ18O) and stable carbon (δ13C) isotope ratios at ~2 – 4 kyr resolution at Site 959 facilitated orbital tuning to eccentricity, obliquity and precession. Bulk elemental composition records, total organic carbon concentrations and dinoflagellate cyst assemblages were also generated to assess paleoenvironmental change.At both sites, warming associated with the onset of the MCO (~17 Ma) was identified as an average SST increase of ~2°C (using the TEX86-H calibration). At ~16.8 Ma, bulk carbonate δ13C gradually increased by ~1‰ at both sites, indicating the onset of the Monterey carbon isotope excursion. Combined with available temperature information from the high latitudes and deep ocean, we assess meridional temperature gradients across the MCO.At ODP Site 959, sediments are characterized by alternations of biogenic silica, carbonates, and terrigenous material (i.e., clays). Following the onset of the MCO (~17 – 16.5 Ma), high variability in the oceanographical setting is reflected in striking Babio peaks, indicating productivity changes. These peaks coincide with lowest SSTs (~28°C) and increased dust supply (increased Fe and Ti) on precession and obliquity timescales. In the same interval, (inner-) neritic dinoflagellate species indicate increased water column stratification. Heterotrophic dinocyst groups vary on timescales coherent with the other geochemical records, relative to comparably stable background abundances of oceanic genera throughout the MCO. Combined, this suggests that a highly dynamic monsoon-driven upwelling regime was present at Site 959 during the MCO. Combined, these patterns imply a highly dynamic African monsoon-driven upwelling regime that intensified at the onset of the MCO.

The Oligocene (33.9 – 23.03 Ma ago) and early Miocene (23.03 – 19 Ma) experienced large climate and ice sheet fluctuations in a most likely unipolar icehouse, with glaciation limited to the Southern Hemisphere. This time interval provides a useful test case for studying polar amplification patterns under atmospheric greenhouse gas concentrations similar to those projected for the future. Large-amplitude climate variability has been recorded close to Antarctica during this time interval, but climatic and environmental conditions and variability in the tropical band are poorly knownpaleoceanographic conditions and sea (sub)surface temperatures (SSTs) will deliver an insight into the climate variability and sensitivity of the lower latitudes under unipolar conditions.Reconstructed surface oceanographic conditions and variations in the depositional environment are based on bulk carbonate stable isotope ratios (δ18O, δ13C), weight% carbonate, magnetic susceptibility and dinoflagellate cyst assemblages at Ocean Drilling Program Site 959, offshore Ghana.. In addition, long term SSTs reconstructions for the Oligocene and early Miocene equatorial Atlantic are derived from lipid biomarker-based paleothermometry (TEX86). Lastly, long term (~31 Ma – 19Ma) atmospheric CO2 concentrations based on stable carbon isotopic fractionation of marine organic carbon and alkenones were generated.The organic carbon isotopic fractionation showshat pCO2 ranged from 280 – 570ppm between ~19 – 33 Ma and shows no signs of large variability, which is consistent with previous findings. The TEX86 indicates that the average SSTs during the Oligocene was ~27℃ which is ~1 – 4℃ colder than in the west Equatorial Atlantic (e.g., ODP Site 929, Ceara Rise), using the same transfer function. Dinoflagellate cyst assemblages indicate upwelling alternated with strong stratification events on ~50 to 100 kyr timescale. Monsoonal upwelling could explain the lower SSTs at Site 959 which is consistent with modern east-west gradients. Subsequent comparison of our equatorial SST record with general circulation modelling studies and SST records from high latitudes should reveal the polar amplification of warming and climate sensitivity on long and short (orbital) timescales during the Oligocene.

The development of in vitro/in vivo translational methods and a clinical trial framework for synergistically acting drug combinations are needed to identify optimal therapeutic conditions with the most effective therapeutic strategies. We performed physiologically based pharmacokinetic–pharmacodynamic (PBPK/PD) modelling and virtual clinical trial simulations for siremadlin, trametinib, and their combination in a virtual representation of melanoma patients. In this study, we built PBPK/PD models based on data from in vitro absorption, distribution, metabolism, and excretion (ADME), and in vivo animals’ pharmacokinetic–pharmacodynamic (PK/PD) and clinical data determined from the literature or estimated by the Simcyp simulator (version V21). The developed PBPK/PD models account for interactions between siremadlin and trametinib at the PK and PD levels. Interaction at the PK level was predicted at the absorption level based on findings from animal studies, whereas PD interaction was based on the in vitro cytotoxicity results. This approach, combined with virtual clinical trials, allowed for the estimation of PK/PD profiles, as well as melanoma patient characteristics in which this therapy may be noninferior to the dabrafenib and trametinib drug combination. PBPK/PD modelling, combined with virtual clinical trial simulation, can be a powerful tool that allows for proper estimation of the clinical effect of the above-mentioned anticancer drug combination based on the results of in vitro studies. This approach based on in vitro/in vivo extrapolation may help in the design of potential clinical trials using siremadlin and trametinib and provide a rationale for their use in patients with melanoma.

The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deepwater circulation in the Atlantic basin and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this problem, we present a multi-site, high-resolution record of biogenic silica (bioSiO2) accumulation from Blake Nose (ODP Leg 171B, western North Atlantic) spanning the early Paleocene to late Eocene time interval (∼65–34 Ma). This record represents the longest single-locality history of marine bioSiO2 burial compiled to date and offers a unique perspective into changes in bioSiO2 fluxes through the early to middle Paleogene extreme greenhouse interval and the subsequent period of long-term cooling. Blake Nose bioSiO2 fluxes display prominent fluctuations that we attribute to variations in sub-thermocline nutrient supply via cyclonic eddies associated with the Gulf Stream. Following elevated and pulsed bioSiO2 accumulation through the Paleocene to early Eocene greenhouse interval, a prolonged interval of markedly elevated bioSiO2 flux in the middle Eocene between ∼46 and 42 Ma is proposed to reflect nutrient enrichment at Blake Nose due to invigorated overturning circulation following an early onset of Northern Component Water export from the Norwegian–Greenland Sea at ∼49 Ma. Reduced bioSiO2 flux in the North Atlantic, in combination with increased bioSiO2 flux documented in existing records from the equatorial Pacific between ∼42 and 38 Ma, is interpreted to indicate diminished nutrient supply and reduced biosiliceous productivity at Blake Nose in response to weakening of the overturning circulation. Subsequently, in the late Eocene, a deepwater circulation regime favoring limited bioSiO2 burial in the Atlantic and enhanced bioSiO2 burial in the Pacific was established after ∼38 Ma, likely in conjunction with re-invigoration of deepwater export from the North Atlantic. We also observe that Blake Nose bioSiO2 fluxes through the middle Eocene cooling interval (∼48 to 34 Ma) are similar to or higher than background fluxes throughout the late Paleocene–early Eocene interval (∼65 to 48 Ma) of intense greenhouse warmth. This observation is consistent with a temporally variable rather than constant silicate weathering feedback strength model for the Paleogene, which would instead predict that marine bioSiO2 burial should peak during periods of extreme warming.

This short paper is comprised of four notes on, or related to, the genus Stictodiscus Greville (1861a: 39) based, for the most part, on specimens in BM (Natural History Museum, London) and a correction to the type designation of Aulacodiscus madagascarensis Tempère noted in a previous publication (Williams 2021: 158)

Highlights • Silicoflagellates include ten Cenozoic genera, starting with Corbisema. • Rotated apical structures begin with Dictyocha byronalis in early Eocene. • Neogene rotation of Dictyocha apical bridge is an independent evolution. • Multi-windowed Stephanopsis are common from early Oligocene. • Paramesocena develops from Stephanopsis and is a possible ancestor of Octactis. Cenozoic silicoflagellate evolution led to ten known genera derived from two groups classified together in Corbisema that may have survived the end-Cretaceous extinction. These underwent rapid diversification and gave rise to at least five genera before the end of the Paleocene, including Dictyocha and Naviculopsis. Important silicoflagellate evolutionary events include the emergence of corner-aligned double skeleton configuration by the early Paleocene and the sinistral rotation of the Dictyocha byronalis apical bridge in early to middle Eocene that evolved into the apically-ringed silicoflagellate genera (e.g., Distephanopsis and Stephanocha). We interpret Paramesocena and Octactis as descended from Stephanocha, although their precise evolutionary paths remain uncertain. The earliest Octactis has thicker apical ring elements than modern O. pulchra, and is here described as the new species O. kosciuszkoi. New combinations are provided for Stephanocha antarctica and Dityocha octangulata. Overall, Cenozoic silicoflagellates show a trend towards more complicated apical geometries and smaller portals. These features enable silicoflagellate double skeletons to form near-spherical skeletal structures that support the external cell boundaries during mitosis. Silicoflagellates employ various strategies to hold double skeletons together and support the cell boundaries across the portal and window openings. Variability is an important feature of the silicoflagellate skeleton and occurs in two broadly different contexts. The first occurs for all silicoflagellate species, with occasional variant skeletal designs distinct from the predominant morphology. The second variability is associated with a single taxon, where multiple unusual skeletal shapes occur in a silicoflagellate plexus over a geologically narrow time interval and limited geographic extent.

The development of in vitro/in vivo translational methods for synergistically acting drug combinations is needed to identify the most effective therapeutic strategies. We performed PBPK/PD modelling for siremadlin, trametinib, and their combination at various dose levels and dosing schedules in an A375 xenografted mouse model (melanoma cells). In this study, we built models based on in vitro ADME and in vivo PK/PD data determined from the literature or estimated by the Simcyp Animal simulator (V21). The developed PBPK/PD models allowed us to account for the interactions between siremadlin and trametinib at PK and PD levels. The interaction at the PK level was described by an interplay between absorption and tumour disposition levels, whereas the PD interaction was based on the in vitro results. This approach allowed us to reasonably estimate the most synergistic and efficacious dosing schedules and dose levels for combinations of siremadlin and trametinib in mice. PBPK/PD modelling is a powerful tool that allows researchers to properly estimate the in vivo efficacy of the anticancer drug combination based on the results of in vitro studies. Such an approach based on in vitro and in vivo extrapolation may help researchers determine the most efficacious dosing strategies and will allow for the extrapolation of animal PBPK/PD models into clinical settings.

Background:Mouse Double Minute 2 protein (MDM2) is a cellular regulator of p53 tumor suppressor (p53). Inhibition of the interaction between MDM2 and p53 proteins is a promising anticancer therapy.Objective:This updated patent review is an attempt to compile the research and achievements of the various researchers working on small molecule MDM2 inhibitors from 2010 to date. We provide an outlook into the future for therapy based on MDM2 inhibition by presenting an overview of the most relevant patents which have recently appeared in the literature.Methods:Literature and recent patents focusing on the anticancer potential of MDM2-p53 interaction inhibitors and its applications have been analyzed. We put the main emphasis on the most perspective compounds which are or were examined in clinical trials.Results:Literature data indicated that MDM2 inhibitors are therapeutically effective in specific types of cancer or non-cancer diseases. A great number of patents and research work around new MDM2- p53 interaction inhibitors, possible combinations, new indications, clinical regimens in previous years prove that this targeted therapy is in the scope of interest for many business and academic research groups.Conclusion:Novel MDM2 inhibitors thanks to higher potency and better ADME properties have shown effectiveness in preclinical and clinical development however the final improvement of therapeutic potential for MDM2 inhibitors might depend on the useful combination therapy and exploring new cancer and non-cancer indications.

Diatomaceous sediments are often prolific hydrocarbon source rocks. In the Paratethys area, diatomaceous rocks are widespread in the Oligo-Miocene strata. Diatomites from three locations, Szurdokpüspöki (Hungary) and Limberg and Parisdorf (Austria), were selected for this study, together with core materials from rocks underlying diatomites in the Limberg area. Bulk geochemical parameters (total organic carbon [TOC], carbonate and sulphur contents and hydrogen index [HI]) were determined for a total of 44 samples in order to study their petroleum potential. Additionally, 24 samples were prepared to investigate diatom assemblages. The middle Miocene diatomite from Szurdokpüspöki (Pannonian Basin) formed in a restricted basin near a volcanic silica source. The diatom-rich succession is separated by a rhyolitic tuff into a lower non-marine and an upper marine layer. An approximately 12-m thick interval in the lower part has been investigated. It contains carbonate-rich diatomaceous rocks with a fair to good oil potential (average TOC: 1.28% wt.; HI: 178 to 723 mg HC/g TOC) in its lower part and carbonate-free sediments without oil potential in its upper part (average TOC: 0.14% wt.). The composition of the well-preserved diatom flora supports a near-shore brackish environment. The studied succession is thermally immature. If mature, the carbonate-rich part of the succession may generate about 0.25 tons of hydrocarbons per square meter. The diatomaceous Limberg Member of the lower Miocene Zellerndorf Formation reflects upwelling along the northern margin of the Alpine-Carpathian Foreland. TOC contents are very low (average TOC: 0.13% wt.) and demonstrate that the Limberg Member is a very poor source rock. The same is true for the underlying and over-lying rocks of the Zellerndorf Formation (average TOC: 0.78% wt.). Diatom preservation was found to differ considerably between the study sites. The Szurdokpüspöki section is characterised by excellent diatom preservation, while the diatom valves from Parisdorf/Limberg are highly broken. One reason for this contrast could be the different depositional environments. Volcanic input is also likely to have contributed to the excellent diatom preservation in Szurdokpüspöki. In contrast, high-energy upwelling currents and wave action may have contributed to the poor diatom preservation in Parisdorf. The hydrocarbon potential of diatomaceous rocks of Oligocene (Chert Member; Western Carpathians) and Miocene ages (Groisenbach Member, Aflenz Basin; Kozakhurian sediments, Kaliakra canyon of the western Black Sea) has been studied previously. The comparison shows that diatomaceous rocks deposited in similar depositional settings may hold largely varying petroleum potential and that the petroleum potential is mainly controlled by local factors. For example, both the Kozakhurian sediments and the Limberg Member accumulated in upwelling environments but differ greatly in source rock potential. Moreover, the petroleum potential of the Szurdokpüspöki diatomite, the Chert Member and the Groisenbach Member differs greatly, although all units are deposited in silled basins.

The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deep-water circulation in the Atlantic basin, and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this problem, we present a multi-site, high-resolution record of biogenic silica (bioSiO2) accumulation from Blake Nose (ODP Leg 171B, western North Atlantic) spanning the early Paleocene through late Eocene time interval (~65‒34 Ma). This record represents the longest single-locality history of marine bioSiO2 burial compiled to date and offers a unique perspective into changes in bioSiO2 fluxes through the early-to-mid Paleogene extreme greenhouse interval and subsequent period of long-term cooling. Blake Nose bioSiO2 fluxes display prominent fluctuations that we attribute to variations in sub-thermocline nutrient supply via cyclonic eddies associated with the Gulf Stream. Whereas few constraints are available on the bioSiO2 flux pulses peaking in the early Paleocene and early Eocene, a middle Eocene interval of elevated bioSiO2 flux between ~46 and 42 Ma is proposed to reflect nutrient enrichment due to invigorated overturning circulation following an early onset of Northern Component Water export from the Norwegian-Greenland Sea at ~49 Ma. Comparison of our North Atlantic record against published Pacific bioSiO2 flux records indicates a diminished nutrient supply to the Atlantic between ~42 and 38 Ma, interpreted as a response to weakening of the overturning circulation. Subsequently, a deep-water circulation regime favoring limited bioSiO2 burial in Atlantic and enhanced bioSiO2 burial in the Pacific was established after ~38 Ma, likely in association with a further invigoration of deep-water export from the North Atlantic. We also observe that Blake Nose bioSiO2 fluxes through the middle Eocene cooling interval (~48 to 34 Ma) are consistently higher than background fluxes throughout the late Paleocene‒early Eocene interval of intense greenhouse warmth. This observation is consistent with a temporally variable rather than constant silicate weathering feedback strength model for the Paleogene, which would instead predict that marine bioSiO2 burial should peak during periods of extreme warming.

Diatomites are prolific hydrocarbon source rocks in many basins worldwide. In the broader Carpathians, diagenetically altered diatomites are called menilites, and menilitic shale successions are regarded as the most prolific hydrocarbon source rocks in the region. The abandoned Sibiciu de Sus quarry, located in the Eastern Carpathian Bend Zone of Romania, provides large exposures of the upper part of the Lower Miocene Upper Menilites, composed of various diatomite lithologies, cherts, menilitic shales and quartz-rich sandstone. The sediments are highly deformed due to soft-sediment deformation and subsequent Miocene to Pliocene contractional tectonics. Twenty-two diatom-bearing samples were examined in order (a) to determine the hydrocarbon source rock potential, (b) to document the diatom assemblages and (c) to interpret the depositional environment. The hydrocarbon potential of the studied rocks is considered good to very good, with an average TOC of 3.77 wt. % (max. 9.57 wt. % TOC) and type II–III kerogen (avg. HI: 384 mg HC/g TOC). Tmax does not exceed 424 °C suggesting that the organic matter is thermally immature. Despite that, the Production Index is high (0.1–0.3), which proves the presence of migrated hydrocarbons. The source potential index (SPI) indicates that the exposed section, if mature, could generate about 1.3 t HC/m2. As the diatom preservation does not enable chemical extraction of individual valves, this study describes only genus-level findings. The diatom assemblages are dominated by Aulacoseira and Actinocyclus, whereas Ellerbeckia, Paralia and Rhaphoneis are rarely observed. The diatom assemblages indicate a nearshore, brackish-water depositional setting.

The so-called Oamaru Diatomite dates from approximately the Eocene–Oligocene Transition (∼34 million years ago), which is widely regarded as one of the most important climatic events of the entire Cenozoic era due to global cooling and the onset of continental-scale Antarctic glaciations. It also represents one of the richest fossil diatom deposits ever known and was first made famous owing to a series of diatom papers by Grove & Sturt. Based primarily on the collection of Sturt, supplemented by slides mounted by Grove, all curated in The Natural History Museum, we consider all 108 diatom taxa from the Oamaru Diatomite that were proposed in these seminal papers by Grove & Sturt and designate type specimens for 87 taxa that were not typified by previous workers, and for which nomenclatural types could be established. Light photomicrographs of all specimens interpreted as types are presented next to reproductions of the line drawings from Grove & Sturt publications to aid future workers on the Oamaru Diatom...

The aim of this paper is to assess efficiency of verification policies used in charity organizations. Verification policy can be introduced to ensure that aid is granted only to people who are eligible for it. However, it bears costs for the program’s organizers. The paper provides a theoretical model assessing economic efficiency of ver ification policy using optimization and simulation methods. Depending on characteristics of the program one of three decisions might be optimal: granting aid without verification, granting aid only to positively verified people or not granting aid at all. Therefore, in order to make a decision about introducing verification policy charity organization should analyze parameters of the program such as: average amount of aid, average cost of verification and percentage of people eligible to obtain help in the program.

A single shell of a pectenoid bivalve was found in the lower part of the Fisher Bench Formation (Fisher Massif, Prince Charles Mountains). In contrast to glacigenic sediments that form extensive outcrops in this area and are almost barren of foraminifera, small pieces of muddy sand attached to this shell contained a rich assemblage of calcareous and siliceous microfossils. The diatom assemblage associated with this shell was dominated by marine benthic forms with abundant Saeptifera, associated with subordinate marine neritic taxa, and Chaetoceros resting spores. Benthic foraminifera are very abundant but of low diversity, strongly dominated by Rosalina globularis with uniform chambers. It is the first Miocene foraminiferal assemblage reported from East Antarctica excluding the Ross Sea area. These new results confirm the early Late Miocene age of the shell that was dated by Sr isotope values in an earlier study, and suggest an initial phase of deposition in a shallow-water (possibly no > 10 m) marine, cold, and possibly oligotrophic environment. After initial burial in microfossil-bearing sediment that was weakly lithified, the shell was eroded and transported to be incorporated in fossil-poor glacigenic sediments. Since transport from a nearby location could have been facilitated by glacial and/or down-slope movements in this fjordal setting, the shell is considered para-autochthonous. Based on the Antarctic foraminiferal fossil records, it appears that through most of the Cenozoic, those parts of the Antarctic continental shelf that were deeper than a few tens of meters, with the exception of the Ross Sea area, were mostly unfavorable for development and/or preservation of calcareous microfossils.

The Oligocene Ruslar Formation, an equivalent of the Maykop Suite, is a potential hydrocarbon source rock in the western Black Sea Basin. In contrast to the offshore areas, the depositional environment and hydrocarbon source rock potential of onshore Bulgaria sediments are largely unknown. Hence, a 14-m-thick section of the Ruslar Formation, exposed near Karadere (Black Cape) along the Black Sea coast, provides an excellent opportunity to study the upper part of the Ruslar Formation. Here, laminated diatomrich mudstones with frequent thin sandstone beds and a prominent concretion horizon are exposed. Furthermore, the fossil diatom assemblages provide a key component to understand the paleoenvironment. Overall, Paleogene diatoms are understudied in the Black Sea Basin and therefore only a genus-level study is undertaken here. The studied Ruslar Formation contain remarkably diverse and wellpreserved diatom assemblage with 23 different genera. The most frequent genera are Paralia, Distephanosira, and Stephanopyxis. Common genera include Coscinodiscus, Hemiaulus, Pseudopodosira, Rouxia, and Xanthiopyxis. Rare taxa include Actinoptychus, Asterolampra, Azpeitia, Delphineis, Distephanosira, Diploneis, Eunotogramma, Eurossia, Lyrella, Liradiscus, Plagiogramma, Radialiplicata, Rutilaria, Saeptifera, and Triceratium. The diatom assemblages together with calcareous nannoplankton, silicoflagellates, and the presence of rare foraminifera indicate a fully marine neritic environment without major salinity variations. The calcareous nannoplankton investigated can be assigned to biozone NP23 (Early Oligocene). The exposed fragment of the Ruslar Formation was deposited after the low salinity "Solenovian event", which represents the maximum isolation of the Paratethys present in the lower part of the NP23. Bulk geochemical parameters from 35 samples (avg. TOC: 1.80% wt.; avg. HI: 226 mg HC/g TOC) show that the exposed part of the Ruslar Formation contains type II-III kerogen and a fair to good hydrocarbon potential. The Ruslar Formation is immature (avg. Tmax: 424 °C), but may generate about 0.5 tons of hydrocarbons per square meter if mature. Biomarker proxies support the low maturity and are characterized by diatom-related biomarkers (24-norcholestane; C25HBI alkanes and thiophenes). Land-plant-derived biomarkers suggest a significant input of angiosperms. Based on biomarker ratios, the depositional environment was oxygen-depleted but probably not strictly anoxic. Reworking of biomass by chemoautotrophic bacteria is suggested by the presence of 28,30-bisnorhopane.

Although previous phylogenetic analyses suggested that the araphid diatom family Plagiogrammaceae is monophyletic, there is still not a clear understanding of relationships among the genera, and the taxonomy of several genera--Dimeregramma and Plagiogramma--remains questionable in light of paraphyly for both genera using molecular and morphological data. We have expanded the available DNA for molecular work for dozens of plagiogrammacean clones and analyzed 29 morphological characters from plagiogrammarian taxa and closely related genera, to increase understanding of the evolutionary history and systematics of the family and re-evaluate the current taxonomical classification of plagiogrammacean genera. The addition of more taxa and more data confirm the results from previous molecular phylogenies: most plagiogrammacean genera are monophyletic, except for Dimeregramma and Plagiogramma. Interestingly, the morphological analysis resolves only Talaroneis and Glyphodesmis as monophyletic. Given these results, we feel there is limited support for retaining Dimeregramma and Plagiogramma as distinct genera, and formally propose amending Plagiogramma and transferring six Dimeregramma species. As the Plagiogrammaceae is also one of the first-diverging clades of pennate diatoms, we also used these molecular data to estimate the age of the family, based on multiple calibration points derived from fossil taxa within or close to the Plagiogrammaceae. The results indicated that the Plagiogrammaceae evolved more than 114 million year ago and its diversification appears to correspond to a time of climate cooling. Additionally, we described a new monotypic genus (Coccinelloidea) with one new species C. gracilis, and five new species within established genera, e.g. Plagiogramma marginalis, Plagiogramma harenae, Plagiogramma porcipellis, Neofragilaria montgomeryii and Psammogramma anacarae.

Silicoflagellate skeletons are made up of siliceous components that interconnect through triple-junctions to form a basket-shaped design made of basal and apical structures. The skeletal framework has a domal shape that can be paired with another to form a double skeleton. For Cenozoic skeletal morphologies, the basal structure consists of a ring of polygonal shape that often includes spines at the basal corners that are directed radially away from the double-skeleton central point, and pikes that point towards the apical axis. The apical structure is made up of elements of less thickness that are connected to the basal ring by struts. The skeletal components of the silicoflagellate conform to a consistently applied set of rules. There is a need to standardize silicoflagellate descriptive terminology in light of recent studies and detailed examination of the elements, spines and pikes that comprise Cenozoic skeletons. Here we review established and recently defined terminology that relates to silicoflagellate skeletons and suggest terminology to standardize future descriptive work.

The composition and distribution of deep-sea sediments is the result of a multitude of climatic, biotic and oceanic conditions relating to biogeochemical cycles and environmental change. Here we utilize the extensive sediment archives of the International Ocean Discovery Program (IODP) and its predecessors to construct maps of deep-sea sediment type across two critical but contrasting boundaries in the Paleogene, one characterised by an interval of extreme warmth (Paleocene/Eocene) and the other by global cooling (Eocene/Oligocene). Ocean sediment distribution shows significant divergence both between the latest Paleocene and Paleocene Eocene Thermal Maximum (PETM), across the Eocene-Oligocene Transition (EOT), and in comparison to modern sediment distributions. Carbonate sedimentation in the latest Paleocene extends to high southern latitudes. Disappearance of carbonate sediments at the PETM is well documented and can be attributed to dissolution caused by significant ocean acidification as a result of carbon-cycle perturbation. Biosiliceous sediments are rare and it is posited that the reduced biogenic silica deposition at the equator is commensurate with an overall lack of equatorial upwelling in the early Paleogene ocean. In the Southern Ocean, we attribute the low in biosiliceous burial, to the warm deep water temperatures which would have impacted biogenic silica preservation. In the late Eocene, our sediment depositional maps record a tongue of radiolarian ooze in the eastern equatorial Pacific. Enhanced biosiliceous deposits in the late Eocene equatorial Pacific and South Atlantic are due to increased productivity and the spin-up of the oceans. Our compilation documents the enhanced global carbonate sedimentation in the early Oligocene, confirming that the drop in the carbonate compensation depth was global.

The widespread occurrence of lower Eocene chert and porcellanite has been viewed as a major paleoceanographic issue since the advent of ocean drilling, and both biotic and abiotic forcings have been proposed to explain it. We present a reconstruction of indurated siliceous sediment (ISS) and preserved biosiliceous sediment (PBS) occurrences in the Atlantic Ocean through the Paleocene and Eocene (~66 through 34 Ma). ISS and PBS distributions reveal dissimilar temporal trends, with the peak of ISS occurrences coinciding with the Early Eocene Climatic Optimum, in line with previous studies. PBS occurrences show a generally increasing trend culminating between 44 and 43 Ma. The common co-occurrence of ISS and PBS, and their coherent geographic distribution lends strong support to the biogenic origin of the precursor to the widespread Paleogene ISS, and argues against an inorganic mode of early Cenozoic chert and porcellanite precipitation. Weight per cent biogenic opal records and trends in linear sedimentation rates indicate two plausible modes of silicification: 1) silicification due to prolonged exposure of biogenic opal-rich sediments to corrosive bottom waters; and 2) silicification due to elevated pressures and temperatures caused by rapid burial of biogenic opal-rich deposits. The confinement of ISS and PBS to proximal sites along continental margins points to the reliance of siliceous sedimentation through the Paleocene and Eocene on terrestrial supply of dissolved silicon. Consistent with this, quantitative siliceous microfossil assemblage records from the Blake Nose in the NW Atlantic indicate that the nutrient-rich marginal rather than oligotrophic pelagic settings hosted the majority of siliceous plankton production through the early Paleogene. The inorganic SiO2 precipitation model is unlikely to have been the dominant mechanism responsible for ubiquitous occurrences of early Paleogene ISS. We favor the biogenic ISS precursor scenario and reconcile it with the low-productivity early Cenozoic oceans by showing that large volumes of biogenic silica were supplied to the western North Atlantic Ocean from the North American margin through the Paleocene and Eocene. Dissolution of this surplus silica was facilitated by an early southwestward flow of young, SiO2-depleted waters from the North Atlantic. All these factors contributed to ISS and PBS focusing in the western North Atlantic through the early Paleogene.

Ocean Drilling Program (ODP) Site 1051 (Blake Nose, western North Atlantic) is of crucial importance for reconstructing diatom evolution and biosiliceous sedimentation patterns through the early Cenozoic period of extreme greenhouse warmth followed by the progressive global cooling. The magnetostratigraphy in Hole 1051A, however, has been subject to divergent interpretations resulting in multi-million-year age control uncertainties, especially for events surrounding the early to middle Eocene transition. To resolve these uncertainties, we compare the stratigraphy of Hole 1051A to the neighboring Holes 1050A, C. We compile the published biomagnetostratigraphic data for both sites and identify three possible magnetostratigraphic solutions for Hole 1051A, the difference being the number of hiati and their duration. In order to identify the most plausible magnetostratigraphic solution for Hole 1051A, we employ the graphic correlation method, in which we compare the depth of individual magnetic reversals in both study sites against an independent proxy, i.e., 49 diatom evolutionary events identified in Holes 1050A,C and 1051A. The distribution of diatom bioevents lends strong support to the presence of two major hiati in both study sites: the upper hiatus juxtaposes magnetozone C21n on C22n, and the lower hiatus juxtaposes magnetozone C23n on C24n, eliminating the record of the initial part of the Early Eocene Climatic Optimum. Diatom, calcareous nannofossil and foraminiferal biostratigraphic markers also indicate that Hole 1051A terminated within magnetozone C28n rather than C27n. This age interpretation is strongly supported by the alignment of high-resolution weight percent biogenic SiO2 records from both study sites. The revised age models developed here for Holes 1050A,C and 1051A have profound consequences for interpretations of western North Atlantic paleoceanographic and paleoclimatic history through the early Paleogene. We propose a revised labelling of the early Eocene carbon cycle perturbations identified to date in Hole 1051A, and show how published Blake Nose δ30Si records change when data from Sites 1050 and 1051 are rescaled to the age models proposed herein. We emphasize that these refinements to the stratigraphy of Sites 1050 and 1051 are based on a study of diatom bioevents, which are here identified and calibrated to the Geomagnetic Polarity Timescale. This successful application of diatom biostratigraphy is a substantial advance toward their future utility in providing high-resolution age control for Paleogene deep-sea sites.

The naviculopsid morphology, which consists of an arch across the minor axis of a basal ring with two corners and sides, is the simplest of the Cenozoic silicoflagellate skeletal designs that include an apical structure. This skeletal design is most often associated with the genus Naviculopsis (geologic range: middle Paleocene to early Miocene), but also occurs among other silicoflagellate genera. This paper interprets the evolutionary history for silicoflagellates of naviculopsid morphology, beginning with a group of large two-sided silicoflagellates from the late early Paleocene, recently placed in genus Pseudonaviculopsis, and ending with a late Miocene group of naviculopsid morphologies associated with Bachmnnocena diodon subsp. nodosa. Between these is Naviculopsis, which has more than twenty species recognized in deep sea sediments. A significant portion of the Naviculopsis taxa discussed in this paper are associated with plexus episodes of abundant and unusual variability from the late Paleocene, late Eocene and early Miocene. A possible explanation of the development of this skeletal morphology, as well as silicoflagellates with more complicated apical structures, is a need to decrease the size of portals, which may better support the cell boundary during mitosis.

Two, rare double skeletons of Corbisema silicoflagellates have been observed from Early and Middle Eocene sediments. Both specimens are in the Star-of-David configuration, with the basal corners of each skeleton aligned with the middle of sibling basal sides. These specimens are of a species that has an elongate basal ring, which shows that skeletons are flipped 180° with respect to one another, rather than simply rotated.

Modern silicoflagellates are known to produce double skeletons, which are considered as pre-division stages; members of modern doublets are aligned at basal corners, using either pikes or organic material between the abbasal surfaces of the basal rings to hold together. In contrast, fossil doublets from the Cretaceous and Paleogene often have the corners of each skeleton oriented between those of the paired member in what is known as the Star-of-David configuration. Until recently, however, virtually nothing was known about the fine structure of fossil double skeletons. As a follow-up to our recent study on extant silicoflagellate doublets, we present a compilation of data on the fossil record of silicoflagellate double skeletons, with particular focus on the Cretaceous and Paleogene. Fossil silicoflagellate double skeleton specimens are extremely rare, with the oldest being from the late Santonian–early Campanian. In order to test whether silicoflagellates may have produced doublets prior to that time, we have constructed three-dimensional computer models of silicoflagellate double skeleton morphologies. Our findings indicate that doublet formation was part of the silicoflagellate reproductive cycle already since early in the evolutionary history of the group, before the development of the basal ring. Two distinct double skeleton configurations developed at some point in this evolution, with the Star-of-David group likely becoming extinct in the Oligocene, and the corner-aligned group represented by the Neogene and modern silicoflagellates. At present, the doublet configuration in fossil silicoflagellates can only be determined confidently with paired skeletons, but the occurrence, position and orientation of pikes may offer useful clues to interpret the doublet configuration from single skeletons. Unusual pike morphologies of some silicoflagellates from the Eocene strongly suggest a Star-of-David configuration. Silicoflagellate skeletal morphologies with pikes appear to be less abundant in the fossil record as double skeletons, and may disassociate more readily than morphologies that lack pikes and are instead held together by organic material between the basal rings.

Silicoflagellate double skeletons are commonly considered to be pre-division stages, even though their life cycle is only partially resolved, especially with respect to reproduction. Double skeletons of the modern silicoflagellate genera Dictyocha Ehrenberg, Distephanus Stohr, and Octactis Schiller are for the first time examined in detail by scanning electron microscopy in order to improve our understanding of how skeletal morphology relates to paired skeletons. A number of genus-specific mechanisms enable sibling skeletons to be held together at their abbasal surfaces, including a zig-zag design of the basal ring achieved via apical structure, strut attachment and pike rotation (in Distephanus and Dictyocha), and the presence of organic material binding the generally planar basal rings (in Octactis). Contrary to what is generally understood, the siblings are not mirror images of one another. Instead, the triple junctions formed by the skeletal elements of each apical structure are transposed across the middle of the dividing cell to produce a copy with the same rotation. Thus, two dome-shaped skeletons represent halves of a more spherical design, which suggests that the role of the silicoflagellate basal ring is to enable double skeleton formation, but the full implications of this have yet to be explored. Although the purpose of double skeleton formation in silicoflagellates remains unclear, observations from the fossil record indicate that differences in the relative alignment of doublet members can have a high significance for phylogeny. Differences in the doublet structure of living silicoflagellates call for a combined biological and geological perspective of the utility of maintaining Dictyocha, Distephanus and Octactis as separate genera.

Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing during late Santonian/early Campanian time within the genus Corbisema. The extraordinary variability of Variramus aculeifera is studied, and a new genus Gleserocha is proposed for taxa with apical structures made of three struts, but without pikes. This new genus includes previously described Variramus wisei and Cornua tapiae and new species G. harrisonii, and is here proposed as a genus transitional between Variramus and Cornua. Two unusual new species of Cornua, C. deflandrei and C. witkowskiana, are also described and a revised terminology is proposed for the skeletal components of Cornua and closely related genera.

Nine samples of broad Late Cretaceous age, previously studied by the respected Russian diatomistA.P. Jousé, were reexamined in order to document the taxonomic composition of silicoflagellates at several localities within the Ural Federal District of Russia. New observations are provided on the range of morphological variability in several important taxa, and a new morphological term, “segment”, is presented for the basal skeletal components of Cornua. An attempt is also made to refine the age determinations for these samples using a recently established silicoflagellate biostratigraphic zonation for theCanadianmargin.Our general conclusion is that the zonation developed based on the Canadian sections can be successfully used to provide age control for sections exposed in the northern part of Eurasia. The samples studied here are probably correlative to the lower Campanian Cornua trifurcata Partial Range Zone and the lowermost Campanian Schulzyocha ruppelii Range Zone of northern Canada. However, the recognition of the Schulzyocha ruppelii Zone is based on the presence of a secondary zonalmarker (Gleserocha tapiae), due to the absence of Schulzyocha. Thismay indicate that only the Cornua trifurcata Zone has interregional applicability, while the Schulzyocha ruppelii Zone may be restricted to the Canadian successions due to the endemism of Schulzyocha. Further studies on Late Cretaceous silicoflagellate paleobiogeography are required to resolve these issues.

The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, quantitative records of siliceous microplankton assemblages from the MECO interval of Ocean Drilling Program (ODP) Site 1051 in the subtropical western North Atlantic Ocean, which are interpreted in the context of published foraminiferal and bulk carbonate stable isotope (δ18O and δ13C) records. High diatom, radiolarian and silicoflagellate accumulation rates between 40.5 and 40.0 Ma are interpreted to reflect a ~ 500 thousand year (kyr) interval of increased nutrient supply and resultant surface-water eutrophication that was associated with elevated sea-surface temperatures during the prolonged onset of the MECO. Relatively low pelagic siliceous phytoplankton sedimentation accompanied the peak MECO warming interval and the termination of the MECO during a ~ 70 kyr interval centered at ~ 40.0 Ma. Following the termination of the MECO, a ~ 200-kyr episode of increased siliceous plankton abundance indicates enhanced nutrient levels between ~ 39.9 and 39.7 Ma. Throughout the Site 1051 record, abundance and accumulation rate fluctuations in neritic diatom taxa are similar to the trends observed in pelagic taxa, implying either similar controls on diatom production in the neritic and pelagic zones of the western North Atlantic or fluctuations in sea level and/or shelf accomodation on the North American continental margin to the west of Site 1051. These results, combined with published records based on multiple proxies, indicate a geographically diverse pattern of surface ocean primary production changes across the MECO. Notably, however, increased biosiliceous accumulation is recorded at both ODP Sites 1051 and 748 (Southern Ocean) in response to MECO warming. This may suggest that increased biosiliceous sediment accumulation, if indeed a widespread phenomenon, resulted from higher continental silicate weathering rates and an increase in silicic acid supply to the oceans over several 100 kyrs during the MECO.

Scanning electron and light microscope observations are presented of Biddulphia brittoniana Kain & Schultze, B. heteroceros Grunow and B. multicornis Grunow. All these species possess unusual modes of chain formation, including entangling spines and clasping of the external tubes of the rimoportulae. The three species are transferred to Cerataulus Ehrenberg based on their loculate valve structure, rows of areolae with internal foramina and external groups of fine pores interrupted by spinules and locular walls, the presence of ocelli pointing away from the apical axis, and of a sipho marginalis. Observations on C. turgidus (Ehrenberg) Ehrenberg, the type species of this genus, are also provided, and the generic description is emended. Morphological features that separate Cerataulus from Pleurosira (Meneghini) Trevisan, Odontella C. Agardh and Zygoceros Ehrenberg are discussed. The overall good preservation of the materials examined here also provides new insights into the structure of the sipho marginalis.

The Middle Eocene Climatic Optimum (MECO) is a major transient warming event that occurred at ~ 40 Ma and reversed a long-term cooling trend through the early and middle Eocene. We report the results of a high-resolution, quantitative study of siliceous microfossils at Ocean Drilling Program Sites 748 and 749 (Southern Kerguelen Plateau, Southern Ocean, ~ 58°S) across a ~ 1.4 myr interval spanning the MECO event. At both sites, a significant increase in biosiliceous sedimentation is associated with the MECO event. Rich siliceous planktonic microfossil assemblages in this interval are unusual in that they are dominated by ebridians, with radiolarians as a secondary major component. Silicoflagellates and diatoms comprise only a minor fraction of the assemblage, in contrast to siliceous microfossil assemblages that characterize modern Southern Ocean sediments. Based on our new siliceous microfossil records, we interpret two ~ 300 kyr periods of elevated nutrient availability in Southern Ocean surface waters which span the peak warming interval of the MECO and the post-MECO cooling interval. A diverse assemblage of large silicoflagellates belonging to the Dictyocha grandis plexus is linked to the rapid rise in sea-surface temperatures immediately prior to peak warmth, and a pronounced turnover is observed in both ebridian and silicoflagellate assemblages at the onset of peak warming. The interval of peak warmth is also characterized by high abundance of cosmopolitan ebridians (e.g., Ammodochium spp.) and silicoflagellates (e.g., Naviculopsis spp.), and increased abundance of tropical and subtropical diatom genera (e.g., Asterolampra and Azpeitia). These observations confirm the relative pattern of temperature change interpreted from geochemical proxy data at multiple Southern Ocean sites. Furthermore, rapid assemblage changes in both autotrophic and heterotrophic siliceous microfossil groups indicate a reorganization of Southern Ocean plankton communities in response to greenhouse warming during the MECO event.

We present four genera of bipolar centric diatoms with linking structures located on the valve face: Rutilaria (including two new species from the Cretaceous), Spinivinculum, Pseudorutilaria and Kisseleviella, which are commonly classified in the family Rutilariaceae. Functional comparison of their linking structures and modes of chain formation shows considerable diversity and does not support a close phylogenetic relationship among them. In order to reflect the probable phylogeny of this group, the Rutilariaceae is retained as a monotypic family, while Kisseleviella is transferred to the Cymatosiraceae. Rymariopsis gen. nov. is proposed as a possible link between the Hemiaulaceae and the Rutilariaceae. Based on the comparison of the stratigraphic ranges of these taxa with other diatoms, we explore the possibility of a close phylogenetic relationship between bipolar centric diatoms with centrally located linking structures and pennate diatoms, as suggested by recent molecular phylogenies. As a consequenc...

Diverse and well-preserved assemblages of early to late Campanian silicoflagellates from the Smoking Hills andMason River formations exposed in the District of Mackenzie, Northwest Territories, Canada include twenty-one known species and five new species in six genera. These include a rare occurrence ofCornua trifurcata and unusual skeletal morphologies of genus Arctyocha. These assemblages provide a new means for biostratigraphic division of the Upper Cretaceous through an expanded silicoflagellate-based zonal framework comprises five zones.

Devon and Ellef Ringnes islands in the Canadian Arctic Archipelago contain well-preserved Santonian through early Campanian silicoflagellates. These occur in three unusual assemblages, which comprise three biostratigraphic zones. The oldest, the Vallacerta tumidula Partial Range Zone of Santonian age, contains an extremely variable microflora that includes species of the poorly-known genus Variramus, two new species of Cornua, and a new genus Umpiocha. The Schulzyocha ruppelii Range Zone of early Campanian age includes several species of the new genus Schulzyocha, reflecting quadrate silicoflagellate skeletal morphologies that lack a basal structure. The youngest assemblage includes the poorly-known species Cornua trifurcata, the nominative taxon of the C. trifurcata Partial Range Zone (proposed by McCartney et al., in press c ; emended herein), which allows a correlation with a silicoflagellate-bearing sequence from the Horton River area, Northwest Territories of Canada. This report presents information on 24 silicoflagellate taxa, proposes 2 new genera, Schulzyocha and Umpiocha, and describes 13 new species and 1 new combination. All of these new taxa disappear by the top of the Campanian Cornua trifurcata Partial Range Zone. These assemblages reveal a new history of silicoflagellate evolution prior to the late Campanian, the period from which most of our prior knowledge about Cretaceous silicoflagellates was derived. The assemblages show progressive change from skeletons with highly variable morphologies to more stable silicoflagellate skeletal geometry. Two important Corbisema species, C. apiculata and C. archangelskiana, appear to be derived from separate lines within Cornua in the latest Santonian and early Campanian. The important Cretaceous genus Lyramula makes its first appearance at the beginning of the Campanian.

Recent studies of Santonian and Campanian sediments from several sites in northern Canada identified two new silicoflagellate genera, many new and unusual species, a Santonian assemblage of Variramus and abundant specimens of the poorly known genus Cornua. This allowed a reassessment of Variramus with information from three new species, and transfer of V. loperi into the new genus Schulzyocha, along with five new species that form an unusual assemblage in the early Campanian. A second new and unusual genus, Umpiocha, and two new species of Cornua provide knowledge of a previously unknown diversity of silicoflagellates in the Santonian. The first appearance of Lyramula is now dated as early Campanian. The occurrence of C. poretzkajae in early Campanian offers new information on the early history and timing of the transition from Cornua to Corbisema. Sediments from higher in the Campanian show development of Corbisema apical plates, and unusual new skeletal morphologies of Arctyocha. These and other discoveries present an improved understanding of early silicoflagellate evolution. Most of the recently described species lack a basal ring, though many of the skeletal morphologies allow for interpretation of a basal plane. Variramus lacks an obvious basal plane, suggesting a more primitive skeletal symmetry, which is interpreted to have given rise to Lyramula (also lacking an apparent basal plane and not known to produce double skeletons). Recent discoveries of rare double skeletons for Corbisema, Schulzyocha and Vallacerta show the skeletons rotated with respect to known Cenozoic configurations. This information, along with a better understanding of Cornua and knowledge of the enigmatic Umpiocha, provides an opportunity to fill part of the 35–40 million year gap between the previously known Albian and late Campanian/Maastrichtian silicoflagellate occurrences. These new interpretations of early silicoflagellate evolution are presented in the context of studies by Deflandre, Gleser and other previous research.

Two new genera of fossil diatoms, Blochia gen. nov. and Nikolaevia gen. nov., are proposed from Kanguk Formation (Upper Cretaceous) outcrops on Devon Island, Canadian Arctic margin. Both genera display morphological features suggesting a relationship with Stellarima Hasle & Sims. Nikolaevia is unusual in having an external opening of the rimoportula in the form of an arcuate canal. Blochia is a genus of large diatoms that are ornamented with spines, and bear a centrally positioned rimoportula with a prominent external tube. Inferred vegetative and resting stages are presented for Nikolaevia symbolica sp. nov., while Blochia magna sp. nov. is considered a resting spore. Observations summarized in the present paper further document the diversity of the Stellarimaceae in one of the oldest available fossil localities providing well-preserved material.

A recently discovered deposit of Late Cretaceous diatoms on Devon Island contains exceptionally well-preserved siliceous microfossils. Two diatom taxa from this deposit, previously identified as belonging to the genera Actinodictyon and Lepidodiscus, were examined with light and scanning electron microscopy. The present study revealed that these two taxa belong to the genus Lepidodiscus. Both were found to display an extremely complex structure of their radially and concentrically undulate valves, involving porous canals, hyaline areas and an external network of thick costae locally thickened to form tubercles. Different number of alternating depressed and elevated sectors located in the marginal zone of the valve, and different structures associated with the external openings of marginal rimoportulae were found to be a sufficient basis for erecting a new species, Lepidodiscus annamariae sp. nov. The excellent preservation of the Devon Island material also allowed for a documentation of the structure of the girdle, composed of multiple open bands.

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75 Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input.

Distribution grids were initially not designed to house significant amount of distributed generation (DG). However, DSO experienced during the last few years a huge increase in penetration rate of renewables. Since DG has a major impact on the voltage level, its connection can result in voltage constraints that limit its integration or lead to grid investments. In such situations, using voltage control may relieve some constraints with no or limited investments. Higher penetration rate of DG will make generation facilities' contribution to voltage control a necessity in a near future, in addition to existing control devices (on-load tap changers). (4 pages)

We present the results of an extensive light-(LM) and scanning electron microscope (SEM) study of internally costate pseudocellate multipolar diatoms previously placed within Biddulphia , Entogonia , Sheshukovia and Triceratium . For the first time, we critically examine the poorly known genus Sheshukovia . We find that the separation of Sheshukovia from Triceratium is justified, as advocated by Gleser (1975, 1984), but also show that Sheshukovia as circumscribed by Gleser (1975, 1984) is a heterogenous taxon comprising at least three morphologically distinct groups. In order to clarify the confused taxonomy of pseudocellate multipolar diatoms, a preliminary phylogenetic analysis is presented, including Triceratium , Sheshukovia , Entogonia , Medlinia and two new closely related genera proposed here: Entogoniopsis and Trilamina . Both new genera have valvocopulae that attach to costae on the valve interior by means of a variety of clasping devices. Entogoniopsis is is characterized by areolate valves and a twofold mechanism for valvocopula attachment, whereas Trilamina possesses extensive hyaline areas and a threefold valvocopula attachment mechanism. The twofold mechanism for valvocopula attachment in Entogoniopsis , and the threefold valvocopula attachment mechanism in Trilamina are here considered synapomorphies supporting the monophyly of the respective taxon. The morphology of 19 species, four of which are new, is documented using both LM and SEM and a further 18 taxa are transferred from elsewhere, observations being based on literature survey and/or LM examination. When original material is available, taxa are typified. Two new morphological terms are proposed: a trifolium is a triradiate raised sector located in the central part of undulate valve faces in some species of Entogoniopsis ; a fossa is a circumferential invagination of the advalvar edge of the valcocopula. These features are found in both new genera proposed herein.

Silicoflagellates are usually associated with simple skeletons made of a domal latticework of rod-shaped elements, known as the apical structure, which is attached to a polygonal basal ring. Silicoflagellate reproduction is poorly understood (Moestrup & Thomsen, 1990) but they are known to divide mitotically associated with the construction of a double skeleton. Such double skeletons connected at the abapical face of the basal ring are observed from Recent and fossil material. Double skeletons of Dictyocha and Distephanus noted in Cenozoic sediments (Dumitricǎ, 1973, pl. 4, fig. 8; Boney, 1976) show basal rings positioned with their corners in close proximity. Ling & Takahashi (1985, pl. 1, fig. 5) and Takahashi et al . (2009, pl. 2, figs 3, 5) illustrate Distephanus with the spines of the two skeletons in exact alignment with one another. Recent work in a Campanian sequence of strata near Horton River, District of Mackenzie in the Northwest Territories, Canada …