Identification key for Pliocene and Quaternary <i>Spiniferites</i> taxa bearing intergonal processes based on observations from estuarine and coastal environments

The use of dinoflagellate cyst assemblages as a tool for palaeo-environmental reconstructions strongly relies on the robustness of cyst identification and existing information on the distribution of the different species. To this purpose, we propose a functional key for the identification of Pliocene and Quaternary Spiniferites bearing intergonal processes and depict the range of morphological variation of the different species on the basis of new observations from estuarine and coastal regions. Accordingly, the description of Spiniferites mirabilis is emended to include the new subspecies Spiniferites mirabilis subsp. serratus. We also report the occasional presence of intergonal processes in Spiniferites bentorii and Spiniferites belerius. This key aims to facilitate identification of this group of Spiniferites bearing intergonal processes and standardize cyst identification among researchers

The absolute abundance calibration project: the <i>Lycopodium</i> marker-grain method put to the test

Traditionally, dinoflagellate cyst concentrations are calculated by adding an exotic marker or “spike” (such as Lycopodium clavatum) to each sample following the method of Stockmarr (1971). According to Maher (1981), the total error is controlled mainly by the error on the count of Lycopodium clavatum spores. In general, the more L. clavatum spores counted, the lower the error. A dinocyst / L. clavatum spore ratio of ~2 will give optimal results in terms of precision and time spent on a sample. It has also been proven that the use of the aliquot method yields comparable results to the marker-grain method (de Vernal et al., 1987). Critical evaluation of the effect of different laboratory procedures on the marker grain concentration in each sample has never been executed. Although, it has been reported that different processing methods (e.g. ultrasonication, oxidizing, etc.) are to a certain extent damaging to microfossils (e.g. Hodgkinson, 1991), it is not clear how this is translated into concentration calculations. It is wellknown from the literature that concentration calculations of dinoflagellate cysts from different laboratories are hard to resolve into a consistent picture. The aim of this study is to remove these inconsistencies and to make recommendations for the use of a standardized methodology. Sediment surface samples from four different localities (North Sea, Celtic Sea, NW Africa and Benguela) were macerated in different laboratories each using its own palynological maceration technique. A fixed amount of Lycopodium clavatum tablets was added to each sample. The uses of different preparation methodologies (sieving, ultrasonicating, oxidizing …) are compared using both concentrations – calculated from Lycopodium tablets - and relative abundances (more destructive methods will increase the amount of resistant taxa). Additionally, this study focuses on some important taxonomic issues, since obvious interlaboratorial differences in nomenclature are recorded

The dinoflagellate cyst genera <i>Achomosphaera</i> Evitt 1963 and <i>Spiniferites</i> Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions

We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973) Londeix et al. 2009, Spiniferites rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica Baltes & 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail

The life and scientific work of William R. Evitt (1923-2009)

Occasionally (and fortunately), circumstances and timing combine to allow an individual, almost singlehandedly, to generate a paradigm shift in his or her chosen field of inquiry. William R. (‘Bill’) Evitt (1923-2009) was such a person. During his career as a palaeontologist, Bill Evitt made lasting and profound contributions to the study of both dinoflagellates and trilobites. He had a distinguished, long and varied career, researching first trilobites and techniques in palaeontology before moving on to marine palynomorphs. Bill is undoubtedly best known for his work on dinoflagellates, especially their resting cysts. He worked at three major US universities and spent a highly significant period in the oil industry. Bill's early profound interest in the natural sciences was actively encouraged both by his parents and at school. His alma mater was Johns Hopkins University where, commencing in 1940, he studied chemistry and geology as an undergraduate. He quickly developed a strong vocation in the earth sciences, and became fascinated by the fossiliferous Lower Palaeozoic strata of the northwestern United States. Bill commenced a PhD project on silicified Middle Ordovician trilobites from Virginia in 1943. His doctoral research was interrupted by military service during World War II; Bill served as an aerial photograph interpreter in China in 1944 and 1945, and received the Bronze Star for his excellent work. Upon demobilisation from the US Army Air Force, he resumed work on his PhD and was given significant teaching duties at Johns Hopkins, which he thoroughly enjoyed. He accepted his first professional position, as an instructor in sedimentary geology, at the University of Rochester in late 1948. Here Bill supervised his first two graduate students, and shared a great cameraderie with a highly motivated student body which largely comprised World War II veterans. At Rochester, Bill continued his trilobite research, and was the editor of the Journal of Paleontology between 1953 and 1956. Seeking a new challenge, he joined the Carter Oil Company in Tulsa, Oklahoma, during 1956. This brought about an irrevocable realignment of his research interests from trilobites to marine palynology. He undertook basic research on aquatic palynomorphs in a very well-resourced laboratory under the direction of one of his most influential mentors, William S. ‘Bill’ Hoffmeister. Bill Evitt visited the influential European palynologists Georges Deflandre and Alfred Eisenack during late 1959 and, while in Tulsa, first developed several groundbreaking hypotheses. He soon realised that the distinctive morphology of certain fossil dinoflagellates, notably the archaeopyle, meant that they represent the resting cyst stage of the life cycle. The archaeopyle clearly allows the excystment of the cell contents, and comprises one or more plate areas. Bill also concluded that spine-bearing palynomorphs, then called hystrichospheres, could be divided into two groups. The largely Palaeozoic spine-bearing palynomorphs are of uncertain biological affinity, and these were termed acritarchs. Moreover, he determined that unequivocal dinoflagellate cysts are all Mesozoic or younger, and that the fossil record of dinoflagellates is highly selective. Bill was always an academic at heart and he joined Stanford University in 1962, where he remained until retiring in 1988. Bill enjoyed getting back into teaching after his six years in industry. During his 26-year tenure at Stanford, Bill continued to revolutionise our understanding of dinoflagellate cysts. He produced many highly influential papers and two major textbooks. The highlights include defining the acritarchs and comprehensively documenting the archaeopyle, together with highly detailed work on the morphology of Nannoceratopsis and Palaeoperidinium pyrophorum using the scanning electron microscope. Bill supervised 11 graduate students while at Stanford University. He organised the Penrose Conference on Modern and Fossil Dinoflagellates in 1978, which was so successful that similar meetings have been held about every four years since that inaugural symposium. Bill also taught many short courses on dinoflagellate cysts aimed at the professional community. Unlike many eminent geologists, Bill actually retired from actively working in the earth sciences. His full retirement was in 1988; after this he worked on only a small number of dinoflagellate cyst projects, including an extensive paper on the genus Palaeoperidinium

Vegetation dynamics in the Northeastern Mediterranean region during the past 23 000 yr: insights from a new pollen record from the Sea of Marmara

International audienceAbstract. High-resolution pollen analysis of core MD01-2430 from the Sea of Marmara (40°47.81' N, 27°43.51' E) allows us to reconstruct the vegetation response to climatic changes during the past 23 cal ka in the Northeastern Mediterranean. Variation in mesic/temperate forest cover indicates major climatic shifts connected to Heinrich Stadial 1, Bölling-Allerød, Younger Dryas and to the onset of the Holocene. Pollen–anthropogenic indicator approach was used to recognize human-induced landscape changes in the Sea of Marmara. The pollen-inferred onset of the Holocene occurs at ca. 11.5 cal ka, indicating that the Northeastern Mediterranean region represents a transitional zone where higher moisture availability supported an earlier forest expansion than the borderlands of the Aegean Sea and Black Sea. Two major forest retreats occurred during the Holocene at ca. 5.5 and 2.1 cal ka. The Holocene forest setbacks are in phase with previously published alkenone-inferred sea-surface temperature decreases in the Sea of Marmara reconstructed from the same core. Our new pollen record testifies the sensitivity of Mediterranean forests to changes in moisture availability, which is driven by changes in high-latitude atmospheric processes (North Atlantic Oscillations and/or Siberian High)

Socialisation of emotions in 5-6 years old children

International audienceL’article présente l’évolution des représentations d’élèves scolarisés au préscolaire en comparant leurs représentations à cinq ans (début d’année) et à six ans (fin d’année). Huit émotions sont prises pour cible : peur, joie, tristesse, colère (émotions « de base » qui ont été analysées dans une étude précédente), et surprise, dégoût, culpabilité et fierté (émotions « secondaires » ajoutées à la présente étude). Un grille posant l’évolution de ces représentations sous forme de trois étapes hiérarchisées est utilisée et validée dans sa forme par cette nouvelle collecte. Les résultats confirment pour les quatre premières émotions étudiées une transformation des représentations. Pour les suivantes, l’application de la grille dégage des évolutions intéressantes plus particulièrement pour le dégoût et la surprise. La culpabilité pose un obstacle clair de vocabulaire. En revanche, la fierté est un sentiment à propos duquel 36% d’élèves de six ans verbalisent un représentation structurée. Les résultats acquis sont discutés en pointant l’intérêt que la communauté éducative aurait à prendre en compte certaines caractéristiques liées à ces évolutions. La question du transfert d’une étape à l’autre de l’évolution est questionnée

Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean during the North Atlantic cold events of the past 50 k.y.

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Sedimentology and sequence stratigraphy of Aquitanian and Burdigalian stratotypes in the Bordeaux area (southwestern France)

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Statistically assessing the correlation between salinity and morphology in cysts produced by the dinoflagellate Protoceratium reticulatum from surface sediments of the North Atlantic Ocean, Mediterranean-Marmara-Black Sea region, and Baltic-Kattegat-Skagerrak estuarine system

Recent studies have correlated dinoflagellate resting cyst morphology to salinity and density variations in the water column, suggesting that morphology can be used for paleoceanographic reconstructions. However, the univariate statistics used by these studies are appropriate only where morphology is related to a single variable. Density is a function of salinity and temperature, so more advanced statistical methods are needed to understand which parameters affect morphology. In this study based on surface (coretop) sediments, a set of environmental variables (sea-surface salinity, temperature, nitrate, and phosphate) was simultaneously correlated to morphological variations seen in resting cysts produced by the dinoflagellate Protoceratium reticulatum (=Operculodinium centrocarpum sensu Wall and Dale). Approximately 3200 measurements were obtained from the North Atlantic Ocean and used to generate a working model based on the Akaike information criterion. Hierarchical partitioning was then applied to establish the independent and joint effects for each predictor variable. Results from these analyses showed that while salinity constitutes the dominant variable affecting process length in the cysts of P. reticulatum in the North Atlantic, it is not the sole explanatory variable and that multicollinearity exists. Temperature and nutrients also showed a significant relationship to the morphology, requiring multiple regression to construct a representative model. The applicability of the North Atlantic working model was finally evaluated by comparing the results to data from the Mediterranean, Marmara, and Black seas, and Baltic-Kattegat-Skagerrak estuarine system. This comparison showed regional differences in morphological-environmental correlation. While salinity constitutes the most important explanatory factor in both the North Atlantic and Baltic-Skagerrak system, this is not so for the Mediterranean-Black Sea region where temperature is the dominant variable. It is concluded that a predictive salinity model based on P. reticulatum cyst morphology has at best a regional application