This paper reports the species composition and distribution of fouling bryozoans in the northern SouthChina Sea. 34 species identified belong to 23 genera, 22 families of fouling bryozoa, of which most of 24 species ...This paper reports the species composition and distribution of fouling bryozoans in the northern SouthChina Sea. 34 species identified belong to 23 genera, 22 families of fouling bryozoa, of which most of 24 species on thebuoys attached to concrete sinkers. The 13 species on platforms mainly included Schizoporella errata and Membranipora savartii. Depth distribution of species, larval settlement behaviour and larvae type of fouling bryozoa are discussed.展开更多
Located in the North-West of the African continent, the Moroccan Middle Atlas constitutes an intra-continental chain within the Atlas domain. It is known by several global geological events such as the Paleocene-Eocen...Located in the North-West of the African continent, the Moroccan Middle Atlas constitutes an intra-continental chain within the Atlas domain. It is known by several global geological events such as the Paleocene-Eocene crisis during the Paleogene, which corresponds to one of the hottest periods on earth with Paleocene-Eocene thermal maximum (PETM). A taxonomic study carried out on the carbonate deposits of the Bekrit-Timahdite Formation from three sections of the Bekrit syncline allowed the identification of 5 species of the Cheilostome and Cyclostome Bryozoans (<em>Cellaria rigida</em>, <em>Cellaria sinuosa</em>, <em>Aimulosia lamellosa</em>, <em>Heteropora</em> and <em>Osthimosia</em>) in bioclastic limestones, nodular limestones, marly and sandy limestones. The interest of Bryozoans as indicators of paleoenvironments and paleoclimates was assessed by examining current communities, in terms of depth evolution as richness and abundance, distribution of taxonomic categories zoarium types, and zooidal morphology. The depositional environment analysis of Bryozoans showed a shallow marine carbonate platform with low sedimentation energy where is registered a relatively warm paleoclimate.展开更多
Gymnolaemata bryozoans produce CaCO3 skeletons of either calcite,aragonite,or both.Despite extensive research,their crystallography and biomineralization patterns remain unclear.We present a detailed study of the micr...Gymnolaemata bryozoans produce CaCO3 skeletons of either calcite,aragonite,or both.Despite extensive research,their crystallography and biomineralization patterns remain unclear.We present a detailed study of the microstructures,min-eralogy,and crystallography of eight extant cheilostome species using scanning electron microscopy,electron backscatter diffraction,atomic force microscopy,and micro-computed tomography.We distinguished five basic microstructures,three calcitic(tabular,irregularly platy,and granular),and two aragonitic(granular-platy and fibrous).The calcitic microstruc-tures consist of crystal aggregates that transition from tabular or irregularly platy to granular assemblies.Fibrous aragonite consists of fibers arranged into spherulites.In all cases,the crystallographic textures are axial,and stronger in aragonite than in calcite,with the c-axis as the fiber axis.We reconstruct the biomineralization sequence in the different species by considering the distribution and morphology of the growth fronts of crystals and the location of the secretory epithelium.In bimineralic species,calcite formation always predates aragonite formation.In interior compound walls,growth proceeds from the cuticle toward the zooecium interior.We conclude that,with the exception of tabular calcite,biomineralization is remote and occurs within a relatively wide extrapallial space,which is consistent with the inorganic-like appearance of the microstructures.This biomineralization mode is rare among invertebrates.展开更多
A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified ov...A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified over time,triggered by environmental changes.The analyzed microfossils consist of palynomorphs(mostly pollen grains,spores,and dinoflagellate cysts),foraminifers and bryozoans.Dinoflagellate cysts and pollen-spores have been recorded in Jurassic to Pleistocene sedimentary outcrops.Dinoflagellate cysts proved to be good indicators for productivity and/or nutrient availability,surface water temperature and chemistry,the position of ancient shorelines and paleoceanographic trends.Pollen and spores allowed reconstruction of floral community and thus characterization of the climate that prevailed on the continent.Foraminifera,recovered from the Lower Cretaceous to the Pleistocene sedimentary rocks,provided information about the bathymetry,showing different marine settings(e.g.,coastal,inner neritic,outer neritic,upper bathyal)in different localities.The bryozoan record is restricted to the Cenozoic.Their colonial growth-forms reflect several environmental conditions such as shallow waters with a low rate of sedimentation,hard substrate and moderate or strong current action for the analyzed localities.The study of the Antarctic ecosystems based on the fossil microbiota and their response to the climate and the continental configuration changes,allowed understanding of the composition and dynamics of the polar environments,which have an important role in the Earth climate.展开更多
文摘This paper reports the species composition and distribution of fouling bryozoans in the northern SouthChina Sea. 34 species identified belong to 23 genera, 22 families of fouling bryozoa, of which most of 24 species on thebuoys attached to concrete sinkers. The 13 species on platforms mainly included Schizoporella errata and Membranipora savartii. Depth distribution of species, larval settlement behaviour and larvae type of fouling bryozoa are discussed.
文摘Located in the North-West of the African continent, the Moroccan Middle Atlas constitutes an intra-continental chain within the Atlas domain. It is known by several global geological events such as the Paleocene-Eocene crisis during the Paleogene, which corresponds to one of the hottest periods on earth with Paleocene-Eocene thermal maximum (PETM). A taxonomic study carried out on the carbonate deposits of the Bekrit-Timahdite Formation from three sections of the Bekrit syncline allowed the identification of 5 species of the Cheilostome and Cyclostome Bryozoans (<em>Cellaria rigida</em>, <em>Cellaria sinuosa</em>, <em>Aimulosia lamellosa</em>, <em>Heteropora</em> and <em>Osthimosia</em>) in bioclastic limestones, nodular limestones, marly and sandy limestones. The interest of Bryozoans as indicators of paleoenvironments and paleoclimates was assessed by examining current communities, in terms of depth evolution as richness and abundance, distribution of taxonomic categories zoarium types, and zooidal morphology. The depositional environment analysis of Bryozoans showed a shallow marine carbonate platform with low sedimentation energy where is registered a relatively warm paleoclimate.
基金funded by projects CGL2017-85118-P,PID2020116660GB-I00(Spanish Ministry of Science and Innova-tion:MCIN/AEI/10.13039/501100011033,“FEDER Una manera de hacer Europa”)。
文摘Gymnolaemata bryozoans produce CaCO3 skeletons of either calcite,aragonite,or both.Despite extensive research,their crystallography and biomineralization patterns remain unclear.We present a detailed study of the microstructures,min-eralogy,and crystallography of eight extant cheilostome species using scanning electron microscopy,electron backscatter diffraction,atomic force microscopy,and micro-computed tomography.We distinguished five basic microstructures,three calcitic(tabular,irregularly platy,and granular),and two aragonitic(granular-platy and fibrous).The calcitic microstruc-tures consist of crystal aggregates that transition from tabular or irregularly platy to granular assemblies.Fibrous aragonite consists of fibers arranged into spherulites.In all cases,the crystallographic textures are axial,and stronger in aragonite than in calcite,with the c-axis as the fiber axis.We reconstruct the biomineralization sequence in the different species by considering the distribution and morphology of the growth fronts of crystals and the location of the secretory epithelium.In bimineralic species,calcite formation always predates aragonite formation.In interior compound walls,growth proceeds from the cuticle toward the zooecium interior.We conclude that,with the exception of tabular calcite,biomineralization is remote and occurs within a relatively wide extrapallial space,which is consistent with the inorganic-like appearance of the microstructures.This biomineralization mode is rare among invertebrates.
文摘A compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin,eastern Antarctic Peninsula,is presented here,in order to show how the microbiota has been modified over time,triggered by environmental changes.The analyzed microfossils consist of palynomorphs(mostly pollen grains,spores,and dinoflagellate cysts),foraminifers and bryozoans.Dinoflagellate cysts and pollen-spores have been recorded in Jurassic to Pleistocene sedimentary outcrops.Dinoflagellate cysts proved to be good indicators for productivity and/or nutrient availability,surface water temperature and chemistry,the position of ancient shorelines and paleoceanographic trends.Pollen and spores allowed reconstruction of floral community and thus characterization of the climate that prevailed on the continent.Foraminifera,recovered from the Lower Cretaceous to the Pleistocene sedimentary rocks,provided information about the bathymetry,showing different marine settings(e.g.,coastal,inner neritic,outer neritic,upper bathyal)in different localities.The bryozoan record is restricted to the Cenozoic.Their colonial growth-forms reflect several environmental conditions such as shallow waters with a low rate of sedimentation,hard substrate and moderate or strong current action for the analyzed localities.The study of the Antarctic ecosystems based on the fossil microbiota and their response to the climate and the continental configuration changes,allowed understanding of the composition and dynamics of the polar environments,which have an important role in the Earth climate.
