Foraminifera of the Type Kiowa Shale, Lower Cretaceous, of Kansas

15 p., 2 pl.http://paleo.ku.edu/contributions.htm

The Species and Stratigraphic Distribution of Caucasina and Aeolomorpella, New Genus (Foraminiferida)

Three fossil forms of raccoons (Procyon priscus Leidy, 1856, P, simus Gidley, 1906, and P. nanus Simpson, 1929) are considered synonyms of P. lo tor (Linnaeus), the only species known from the Pleistocene of North America. Localities from which fossil Procyon have been reported are mapped, along with unpublished records of the genus

New Acritarches from the Early Devonian (Late Gedinnian) Haragan Formation of Oklahoma, U.S.A.

Three distinctive new genera of acritarchs, microplankton of probable algal origin, are described from the Early Devonian (Late Gedinnian) Haragan Formation of Oklahoma. Ozotobrachion includes two new species: O. dactylos (type species) and O. dicros. Fimbriaglomerella (type species, F. divisa) and Riculasphaera (type species, R. fissa) are both, for the present, monotypic

Some Eocene and Oligocene Phytoplankton from the Gulf Coast, U.S.A.

Four distinctive new dinoflagellate species are described from the Gulf Coast Tertiary. Two of these are made the bases for new genera: Phthanoperidinium, type species P. amoenum from the Oligocene of Mississippi, and Heteraulacacysta, type species H. campanula from the Eocene of Alabama. These genera are made the bases for the new families Phthanoperidiniaceae and Heteraulacacystaceae. A new species of Homotryblium is described from the Oligocene of Mississippi and one of Operculodinium from the Eocene and Oligocene. The new combination Heteraulacus polyedricus (Pouchet) is made for the former Peridinium. Two new acritarch genera Ascostomocystis and Cyclopsiella, each have two new species. The species Ascostomocystis hydria occurs in the Alabama Eocene and A. potane in the Mississippi Oligocene. Both Cyclopsiella elliptica and C. vieta occur in the Oligocene of Mississippi

Linkages between rapid climate variability and deep‐sea benthic foraminifera in the deep Subantarctic South Atlantic during the last 95 kyr

We present a high-resolution record of benthic foraminifera fauna from a sediment core retrieved from the South Cape Basin (Subantarctic South Atlantic) spanning the last glacial cycle (95 kyr). Information provided by benthic foraminiferal assemblages together with paleoclimate proxies from the same core allow us to interpret changes in the style of primary production (episodic vs sustained) in relation to abrupt climate oscillations. Our results indicate that fluctuations in the abundance of the phytodetritus- related species, Epistominella exigua, are concomitant with millennial scale high latitude climate perturbations. Episodic phytoplankton blooms increased during a negative mode of the bipolar seesaw, irrespective of the magnitude of the perturbation (i.e., HS versus non-H stadial events). We provide a hypothesis linking the frequency and intensity of these events to atmospheric perturbations, interhemispheric climate variability and millennial scale changes in atmospheric CO2. A notable exception to the overall pattern is the generally high abundance of E. exigua across the globally synchronous onset of glacial MIS 4, a period generally characterized by increased dustiness and low quality organic carbon as inferred by the percentage of the non-phytodetritus species. This highlights the special characteristics governing the onset of MIS 4 in the Subantarctic

Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard

We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean warming may be fueling the destabilization of shallow methane hydrate. The ?13C values of benthic and planktonic foraminifera at the methane seep sites show distinct intervals with negative values (as low as ?27.8‰) that do not coincide with the present-day depth of the sulfate methane transition zone (SMTZ). These intervals are interpreted to record long-term fluctuations in methane release at the present-day landward limit of the gas hydrate stability zone (GHSZ). Shifts in the radiocarbon ages obtained from planktonic foraminifera toward older values are related to methane-derived authigenic carbonate overgrowths of the foraminiferal tests, and prevent us from establishing the chronology of seepage events. At shallower water depths, where seepage is not presently observed, no record of past methane seepage is recorded in foraminifera from sediments spanning the last 14 ka cal BP (14C-AMS dating). ?13C values of foraminiferal carbonate tests appear to be much more sensitive to methane seepage than other sediment parameters. By providing nucleation sites for authigenic carbonate precipitation, foraminifera thus record the position of even a transiently stable SMTZ, which is likely to be a characteristic of temporally variable methane fluxes

Paleoenvironmental reconstruction of Challenger Mound initiation in the Porcupine Seabight, NE Atlantic

The understanding of the paleoenvironment during initiation and early development of deep cold-water coral carbonate mounds in the NE Atlantic is currently a focus of international research. The Integrated Ocean Drilling Program (IODP) Expedition 307 drilled the 155 m high Challenger Mound in the Porcupine Seabight (SW off Ireland) in order to investigate for the first time sediments from the base of a giant carbonate mound. In this study we focus in high resolution on 12 m of sediments from Site 1317 encompassing the mound base. The mound initiation and start-up phase coincide with the intensification of the Northern Hemisphere Glaciation (INHG) at around 2.7 Ma. Further carbonate mound development seems to be strongly dependent on rapid changes in paleoceanographic and climatic conditions at the Pliocene–Pleistocene boundary, especially characterized and caused by the interaction of intermediate water masses, the Mediterranean Outflow Water (MOW), the Eastern North Atlantic Water (ENAW) and the influence of Southern Component Water (SCW). This study is based on well-established proxies such as δ18O and δ13C of planktonic (Globigerina bulloides) and benthic foraminifera (Fontbotia wuellerstorfi, Discanomalina coronata, Lobatula lobatula, Lobatula antarctica, and Planulina ariminensis) as well as grain size parameters to identify the paleoenvironmental and paleoecological setting favourable for the initial coral colonization on the mound. Stable oxygen and carbon isotope records of benthic foraminiferal species indicate that L. lobatula provides a reliable isotopic signature for paleoenvironmental reconstructions. In particular, δ18O values of L. lobatula indicate that initial mound growth started in a glacial mode with moderate excursions in δ18O values. Carbon isotope values of D. coronata are significantly offset compared to other epibenthic species. This offset may be related to vital effects. Bottom water temperatures, calculated using standard equations based on δ18O of foraminiferal tests, range between 7 and 11 °C, consistent with the known temperature range conducive for cold-water coral growth and development. Bottom currents transporting intermediate water masses of southern origin (Mediterranean and Bay of Biscay) enhanced at 2.6 Ma supporting first coral settlements with the INHG. The benthic δ13C and the sortable silt records indicate that the early Pleistocene hydrodynamic regime was characterized by weaker current intensities associated with vertical movements of MOW or its replacement by SCW at intermediate depth. After these sluggish phases enhanced MOW flow dominated again and led to stronger current intensities and most probably sediment erosion on Challenger Mound. Erosion in combination with early diagenetic (oxidation) processes overprinted the sediment layers as indicated by dissolved coral skeletons, the increase in Ca-content and sediment density, minimum δ13Cplanktonic values, as well as the occurrence of gypsum and pyrite, implying a careful evaluation of original and overprinted geochemical signals. We conclude that the Challenger Mound development was already influenced by short-term variability of water masses from southern origin and possible erosional events comparable to the late Pleistocene setting

Dinoflagellate genetics and DNA characterization : (dinoflagellates, evolution, nucleus, DNA, genetics, mesocaryota)

Nuclear features of dinoflagellates that were used origin ally to support the Mesocaryota concept are reviewed. Although dinoflagellates possess some procaryotic nuclear features, the remainder of the cell is obviously eucaryotic. The fibrillary diameter of the chromatin, low level of chromosomal basic proteins, membrane attachment of the chromosomes and swirl pattern seen in sectioned chromosomes all support a procaryotic affinity. On the other hand, the repeated and highly complex DNA, S-phase of DNA synthesis, and the presence of basic proteins and extra nuclear spindle support the contention that dinoflagellates are eucaryotic. The possession of both procaryotic and eukaryotic nuclear features indicate that this group evolved relatively early in biological time. A review is made of recent attempts to analyze the genetics of this algal group. Although incomplete, these studies have suggested that dinoflagellates have an unusual meiotic process.ALFRED R. LOEBLICH, III, The Biological Laboratories, Harvard University, Cambridge, MA

Natural and human-induced Holocene paleoenvironmental changes on the Guadiana shelf (northern Gulf of Cadiz)

Three contrasting sedimentary environments on the continental shelf off the Guadiana River (northern Gulf of Cadiz) were integrated in a chronological framework and analysed in terms of sedimentology and benthic foraminiferal assemblages to understand the Holocene paleoenvironmental evolution. The analysed environments differ in terms of their depositional regimes and benthic foraminiferal assemblages. However, a dominant fluvial origin of the sand fraction was observed in all three environments. Holocene sedimentary processes were mainly controlled by natural (sea level changes and climate variations) and human-induced processes (e.g. deforestation, agriculture) along four evolutionary stages. The three older stages were mainly influenced by natural processes, such as sea level variations and fluvial inputs, whereas the most recent stage reflects a combination of climatic- and human-induced processes. A deepening of sedimentary environments related to a period of rapid sea level rise, strongly influenced by river discharges occurred from c. 11,500 to c. 10,000 cal. yr BP. A reduction in sediment export to the shelf, as a result of the continuous and rapid sea level rise and enhanced estuary infilling reflects the second stage, from c. 10,000 to c. 5000 cal. yr BP. The beginning of the third stage, from c. 5000 to c. 1500–1000 cal. yr BP, is marked by a sea-level slowdown and the relatively stable climate and environmental conditions. The fourth stage, from c. 1500–1000 cal. yr BP to Recent times, reflects the intensification of human-induced processes and climatic variability in the Guadiana River basin. This stage also reflects modern depositional conditions, with the formation of a proximal prodeltaic wedge and a distal muddy body

Development of a new pan-European testate amoeba transfer function for reconstructing peatland palaeohydrology

In the decade since the first pan-European testate amoeba-based transfer function for peatland palaeohydrological reconstruction was published, a vast amount of additional data collection has been undertaken by the research community. Here, we expand the pan-European dataset from 128 to 1799 samples, spanning 35° of latitude and 55° of longitude. After the development of a new taxonomic scheme to permit compilation of data from a wide range of contributors and the removal of samples with high pH values, we developed ecological transfer functions using a range of model types and a dataset of ∼1300 samples. We rigorously tested the efficacy of these models using both statistical validation and independent test sets with associated instrumental data. Model performance measured by statistical indicators was comparable to other published models. Comparison to test sets showed that taxonomic resolution did not impair model performance and that the new pan-European model can therefore be used as an effective tool for palaeohydrological reconstruction. Our results question the efficacy of relying on statistical validation of transfer functions alone and support a multi-faceted approach to the assessment of new models. We substantiated recent advice that model outputs should be standardised and presented as residual values in order to focus interpretation on secure directional shifts, avoiding potentially inaccurate conclusions relating to specific water-table depths. The extent and diversity of the dataset highlighted that, at the taxonomic resolution applied, a majority of taxa had broad geographic distributions, though some morphotypes appeared to have restricted ranges