Nothia ex gr. excelsa (Grzybowski, 1898), ‘flysch-type’ agglutinated foraminifera from the Karpatian (Early-Miocene) of Hungary

Abstract

Nothia ex gr. excelsa (Grzybowski, 1898) branched, agglutinated, tubular foraminifera is documented for the first time from the Karpatian (latest Burdigalian) molasse sediments of the Paratethys. Excellently preserved specimens allowed the study of the macro- and microstructure of the test using reflected and polarized light microscopes, SEM and Raman spectroscopy. The mineralogical components of the agglutinated grains, the appearance of the protruded aperture with a scalloped-edge, the microstructure of the bilamellar wall, the presence of the calcite microgranular cement could all be described in detail. Based on autecology, the test morphology and the associated fauna indicate that Nothia ex gr. excelsa was a surface-dwelling detritivore with a seasonal-phytophagous mode of life.     

Origin and evolution of an Upper Jurassic complex of carbonate buildups from Zegarowe Rocks (Kraków–Wieluń Upland, Poland)

The Upper Jurassic complex of Zegarowe Rocks is situated on the Kraków–Wieluń Upland in southern Poland. The complex is dominated by massive limestones representing carbonate buildups. The successive stages of carbonate buildup development include: colonisation, aggradational growth and progradation phases. In the colonisation phase, on top of loose peloidal-ooid sands micritic peloidal thrombolites developed. Peloidal and agglutinated thrombolites and stromatolites proliferated during the aggradational growth phase, whereas the progradation phase was characterised by shallowing and related development of agglutinated stromatolites with coprolites. The latter were the effect of periodical stabilisation of detrital sediments by microbial mats. The Zegarowe Rocks complex developed upon an elevation of the Late Jurassic stable northern shelf of the Tethys. This elevation was formed due to local decrease in subsidence rate, induced by the presence of a Palaeozoic granitoid intrusion in the shelf substratum. The carbonate buildups of the Zegarowe Rocks complex, initially developing as sediment-starved mounds upon fault-controlled intraplatform highs under strongly restricted background sedimentation rate, were replaced by agglutinated microbial reefs.     

Palaeobiology and evolution of the earliest agglutinated Foraminifera: Platysolenites, Spirosolenites and related forms

Tubular agglutinated fossils of Platysolenites antiquissimus Eichwald, 1860, P. cooperi n.sp. and Spirosolenites spiralis Glaessner, 1979 are examined from selected lower Cambrian successions in Avalonia (England; Wales; Newfoundland) and Baltica (Russia and Estonia). Platysolenites cooperi n.sp. is shown to extend below the first appearance of P. antiquissimus in the Neoproterozoic-Cambrian boundary stratotype region, SE Newfoundland, and to occur at higher stratigraphic levels in Wales and Finnmark. Taphonomic, teleological and ultrastructural studies on well-preserved material are consistent with a similar grade of organization and mode of life for P. antiquissimus and the living astrorhizacean foraminiferid Bathysiphon. However, agglutinated proloculi are here described from both rectilinear P. antiquissimus and coiled S. spiralis, which suggests that neither were typical astrorhizaceans.     

The morphology and ecology of a new large agglutinated Antarctic foraminifer (Textulariina: Notodendrodidae nov.)

A now genus and species of large (up to 38 mm) arborescent foraminifer was found in abundance (100/m²) in an ice-covered embayment of the Ross Sea, Antarctica. In contrast to highly productive adjacent areas, this oligotrophic embayment is bathed with water coming from beneath the extensive Ross Ice Shelf. Analyses demonstrate no primary productivity and very low bacterial populations in the water column: however, benthic diatom productivity and bacterial populations are substantial. This arborescent foraminifer is well adapted to these unusual conditions. It is of complex construction with a subcentral double-walled bulb, a dendritic root system, and a stem which gives rise to branches. The bulb and root system reside in the sediment. The stem extends from the top of the bulb through from I to 3 mm of sediment into the overlying water, where it terminates in branches. Laboratory and in situ observations have demonstrated that the organism captures bottom sediments, which are brought into suspension by the activities of larger benthic invertebrates, in cytoplasm extending from the branches and stem. Examination of cytoplasmic composition and arrangement indicates that feeding lakes place infrequently.