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Biomineralization in living hypercalcified demosponges: Toward a universal mechanism?
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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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RBINS Staff Publications
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Biostratigraphy of the Danian/Selandian transition in the southern Tethys. Special reference to the Lowest Occurrence of planktic foraminifera Igorina albeari.
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RBINS Staff Publications
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Biotic and abiotic determinants of the formation of ant mosaics in primary Neotropical rainforests
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RBINS Staff Publications 2019
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Biotic impact of Eocene thermal maximum 2 in a shelf setting (Dababiya, Egypt).
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The Paleocene-Eocene thermal maximum (PETM) initiated a global biotic event with major evolutionary impacts. Since a series of minor δ13C and δ18O excursions, indicative of hyperthermals, now appears to characterize early Eocene climate, it remains to be investigated how the biosphere responded to these warming events. We studied the Esna Formation at Dababiya (Nile Basin, Egypt), in order to identify Eocene thermal maximum 2 (ETM-2) and to evaluate the foraminiferal and ostracode patterns. The studied interval generally consists of gray-brown marls and shales and is interrupted by a sequence of deviating lithologies, representing an early Eocene Egyptian environmental perturbation that can be linked to ETM-2. The ETM-2 interval consists of brownish shales (bed 1) to marls (bed 2) at the base that grade into a foraminifera-rich chalky limestone (bed 3) at the top. This conspicuous white limestone bed forms the base of the Abu Had Member. A distinct negative δ13C excursion of approximately 1.6‰ is recorded encom- passing this interval and a second negative δ13C shift of 1‰ occurs 5 m higher. These two isotope events are situated respectively in the basal and lower part of the calcareous nannoplankton zone NP11 and appear to correlate with the H1 and H2(?) excursions observed in the deep-sea records. The lower δ13C excursion is associated with benthic foraminiferal and ostracode changes and settlement of impoverished anomalous foraminiferal (planktic and benthic) assemblages, indicating a transient environmental anomaly, disrupting the entire marine ecosystem during ETM-2. Our observations indicate some similarities between the sedimentary and biotic expressions of ETM-2 and the PETM at Dababiya, pointing to similar processes operating in the Egyptian Basin during these global warming events.
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Bird bones from Trou de Chaleux and the human exploitation of birds during the late Magdalenian in Belgium
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The Trou de Chaleux is a cave site located in Belgium. It delivered a rich late Magdalenian material culture constituted mainly of lithic artefacts but also including bone industries and figurative art. This paper presents the results of the analysis of the large collection of bird remains recovered by E. Dupont in 1865, which was yet unstudied from taphonomical and archaeozoological perspectives. In addition to the taxonomic identification, surface alterations were investigated based on a macro- and microscopic analysis, including an analysis of wear traces and elementary composition. Special attention is devoted to the presence of human modifications such as disarticulation or butchering marks, traces of heating, presence of colourants and traces of bone working. The taphonomic history of the bird assemblage is reconstructed and the use of birds by humans characterized, as well as their importance in past human activities. We also discuss evidence for seasonal exploitation and for reconstructing the local environment and integrate our results with evidence from other Magdalenian assemblages from north-western Europe. At Trou de Chaleux, birds were used for food, as raw material for bone working and for symbolic purposes. The exploitation of avian products was intense, and species have been used for several purposes such as the raven and snowy owl having been exploited both for food and for symbolic reasons. Large bird bones were used as raw material to produce artefacts, but the use-wear analysis did not evidence unambiguous traces related to the use of the objects produced. Despite several limiting factors, the bird material from Trou de Chaleux considerably increases the knowledge of past human exploitation of birds during the late Magdalenian in north-western Europe.
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RBINS Staff Publications 2020
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Bird remains from Late Medieval and Postmedieval sites in Brussels, Belgium
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RBINS Staff Publications
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Black adzes in the Early Neolithic of Belgium. Contribution of the Raman microspectrometry and petrography in the characterization and sourcing
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Ancient Neolithic (Linear Pottery Culture) adzes originate from settlements and workshops accompany the neolithization of Belgium. They are made from a wide range of extraregional lithic raw materials such as metamorphic green rocks (amphibolite) and black volcanic rocks (‘basalt’) beside more local or regional raw material as flints, light-coloured (sedimentary and lightly metamorphic) quartzites and fine-grained black rocks. Another material source included black lydites (Cambrian nodular phtanite of Céroux-Mousty and Lower Namurian banded phtanites) and dark grey Lower Namurian silicified sandstones called ‘Micaceous sandstones of Horion-Hozémont’. The discovery of the workshop of Noir Fontaine near the city of Liège in the 1970s and 1980s provides exceptional assemblage available for updating analytical studies. This research focuses on the multi-scale characterization, the discrimination and sourcing of the different types of fine-grained black materials composing Ancient Neolithic adzes found in Belgium. Their black colour results from finely dispersed organic matter, but the absence of palynomorphs does not allow a biostratigraphic ascription. Additional petrographical analyses (Optical Petrography - OP, Scanning Electronic Microscopy - SEM), X-ray diffraction (XRD), chemical analyses (Energy Dispersive Spectroscopy - EDS) and measuring the degree of graphitization of the organic matter through Raman microspectrometry have been decisive in identifying the geological and geographical provenances by comparing the acquired results with geological reference samples collected in the field or through reference collections. The distribution of the different black coloured rocks shows that Cambrian lydites are coming from a very restricted area and were preferred to other more local rock sources.
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RBINS Staff Publications 2021
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Body distribution of toxic peptides in larvae of a pergid and an argid sawfly species
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RBINS Staff Publications 2020
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Body length estimation of the European eel Anguilla anguilla on the basis of isolated skeletal elements
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Using a large series of dry skeletons of modern European eel Anguilla anguilla (Linnaeus, 1758) from Belgium and the Netherlands, the relationship between fish length and individual bone measurements is investigated. The aim of the study is to provide adequate regression equations between both parameters. This methodology is relevant for both palaeoecological and ecological researches since isolated skeletal elements survive in large numbers on archaeological sites and in the stomach contents, faeces or regurgitations of piscivorous animals. The predictive value for the length estimations is explored for various skeletal elements and the accuracy of the obtained regression formulae is compared to that of the formulae already existing in literature. Particular attention is paid to the use of vertebrae, taking into account that different morphotypes can be distinguished amongst them.
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Body size and dispersal mode as key traits determining metacommunity structure of aquatic organisms
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