Search publications of the members of the Royal Belgian institute of natural Sciences
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Living hypercalcified sponges
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Biomineralization in living hypercalcified demosponges: Toward a universal mechanism?
- Massive skeletons of living hypercalcified sponges, representative organisms of basal Metazoa, are uncommon models to improve our knowledge on biomineralization mechanisms and their possible evolution through time. Eight living species belonging to various orders of Demospongiae were selected for a comparative mineralogical characterization of their aragonitic or calcitic massive basal skeleton. The latter was prepared for scanning and transmission electron microscopy (SEM and TEM), selected-area electron diffraction (SAED) and X-ray diffraction (XRD) analyses. SEM results indicated distinctive macro- and micro-structural organizations of the skeleton for each species, likely resulting from a genetically dictated variation in the control exerted on their formation. However, most skeletons investigated shared submicron to nano-scale morphological and crystallographical patterns: (1) single-crystal fibers and bundles were composed of 20 to 100nm large submicronic grains, the smallest structural units, (2) nano-scale likely organic material occurred both within and between these structural units, (3) {110} micro-twin planes were observed along aragonitic fibers, and (4) individual fibers or small bundles protruded from the external growing surface of skeletons. This comparative mineralogical study of phylogenetically distant species brings further evidence to recent biomineralization models already proposed for sponges, corals, mollusks, brachiopods and echinoderms and to the hypothesis of the universal and ancestral character of such mechanisms in Metazoa.
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New datings and considerations on the chronology of Upper Palaeolithic sites in the Great Eurasiatic Plain.
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Paléoenvironnement et chronologie du Paléolithique dans la Grande Plaine eurasiatique depuis 150.000 ans.
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Revised stratigraphy and chronology of the Willendorf II sequence, Lower Austria
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A New Hamburgian Concentration at Siedlnica 17 in the Kopanica Valley (SW Poland).
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Anthracology and Past Vegetation Reconstruction. In J. SVOBODA (ed.): Pavlov I. Northwest. The Upper Paleolithic burial and its settlement context.
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Advantages of high quality SWIR bands for ocean colour processing: Examples from Landsat-8
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SIMilarity Environment Correction (SIMEC) applied to MERIS data over inland and coastal waters
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Cloud and cloud shadow identification for MERIS and Sentinel-3/OLCI
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CoastColour Round Robin datasets: a database to evaluate the performance of algorithms for the retrieval of water quality parameters in coastal waters
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A SWIR based algorithm to retrieve total suspended matter in extremely turbid waters
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A single algorithm to retrieve turbidity from remotely-sensed data in all coastal and estuarine waters
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Salinity predicts the distribution of chlorophyll a spring peak in the southern North Sea continental waters
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Analysis of high frequency geostationary ocean colour data using DINEOF
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A high-resolution DEM for the Top-Palaeogene surface of the Belgian Continental Shelf
- A 1:250,000 scale map of the surface of the Top-Palaeogene for the Belgian Continental Shelf was created based on extensive analyses of older and recent geological and geophysical datasets. The Top-Palaeogene surface is an important polygenetic unconformity that truncates older strata of the Palaeogene and to a smaller extent some of Neogene age from the overlying Quaternary deposits. As such it represents the base of the latter. The represented surface has been diachronously shaped and reworked through Late Quaternary times by different geological processes (e.g. fluvial, marine, estuarine, periglacial). Additionally, the offshore surface has been attached to the landward Top-Palaeogene surface and was transformed into a uniform 3D surface allowing new and better interpretations to be used in fundamental and applied research underpinning both scientific purposes (e.g. geology, archaeology, palaeogeography), and commercial applications (e.g. wind farms, aggregate extraction, dredging).
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Sympatric Dreissena species in the Meuse River: towards a dominance shift from zebra to quagga mussels
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The Early Carboniferous progymnosperm Protopitys: new data on vegetative and fertile structures, and on its geographic and stratigraphic distribution
- We review progress made during the last 25 years in our understanding of the Protopityales, Early Carboniferous plants belonging to the extinct group of the progymnosperms. Recent studies support previous observations that the only genus of this order, Protopitys, included large arborescent plant with trunks up to 1 m in diameter. All branch orders had an oval eustele, secondary xylem with small rays and tracheid pitting ranging from circular bordered to scalariform bordered, and vascular traces to lateral appendages emitted in an alternate to subopposite distichous arrangement. Leaf morphology remains unknown. New material also confirms that fertile organs of Protopitys consist of branching systems bearing elongated sporangia terminally. Spores have a perispore and range in two size groups, which has been interpreted as a primitive stage of heterospory. The dense wood and fertile parts of Protopitys are comparable to those of the aneurophytalean progymnosperms of the Devonian, but Protopitys is distinct by its eustelic primary vascular system, and its affinities are still uncertain. The genus is now documented from at least nine localities in Europe, North America and Australia. Recent discoveries also indicate that it was present through the whole Mississippian, from the middle Tournaisian to the Serpukhovian.
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Brabantophyton, a new genus with stenokolealean affinities from a Middle to earliest Upper Devonian locality from Belgium
- A new taxon with stenokolealean affinities, Brabantophyton runcariense gen. et sp. nov., is described from seven pyrite permineralized axes collected from the mid Givetian to earliest Frasnian (late Middle to earliest Upper Devonian) locality of Ronquières (Belgium). The specimens include stems and lateral organs. The stems are characterized by a protostele dissected into three primary ribs, each of them dividing into two secondary ribs. The protostele shows a central protoxylem strand and numerous strands distributed along the midplanes of the ribs. The vascular supply to lateral organ is composed of two pairs of traces, produced at the same time by the two ribs issued from a single primary rib of the protostele. Within each pair, the shape and the size of the traces are unequal: one is T-shaped and the other is oval to reniform. The T-shaped traces of each pair face each other. The inner cortex of the lateral organs is parenchymatous and the outer cortex is sparganum-like. The specimens of Brabantophyton runcariense show many similarities with the stenokolealean genus Crossia virginiana Beck and Stein, but the vascular supply of lateral organs of the latter consists of a more symmetrical and distinctively simpler pair of traces. Brabantophyton represents the first report of the Stenokoleales in southeastern Laurussia. The characteristics of the Brabantophyton protostele compare better with the anatomy of the radiatopses, and, within the latter, particularly with basal seed plants.
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DNA barcoding Congolese snakes
