REVUE DE MICROPALEONTOLOGIE最新文献

{"title":"Taphonomy of radiolarian and diatom fossils preserved within Oligocene trace fossils","authors":"Akihide Kikukawa ,&nbsp;Yoshiaki Aita ,&nbsp;Noboru Furukawa ,&nbsp;Nobuhiro Kotake","doi":"10.1016/j.revmic.2023.100754","DOIUrl":"10.1016/j.revmic.2023.100754","url":null,"abstract":"<div><p>This study deals with the taphonomy of siliceous microfossils preserved in trace fossils. With this objective, we chose to study trace fossils (<em>Tasselia ordamensis</em>) from the Oligocene Okubo Mudstone Member of the Nishinoomote Formation (Kumage Group), exposed on Tanegashima Island, Kagoshima, southwest Japan. Specifically, we examined microfossil distribution patterns, their mode of occurrence, and state of preservation, within the infill of the trace fossil and as well as from the surrounding host mudstone. This has enabled us to establish that there is a significant siliceous microfossil preservation advantage within trace fossils in mudstones that have been subject to burial diagenesis. The following three conclusions can be made</p><p>(1) Relatively well-preserved radiolarian and diatom fossils are distributed unevenly within the trace fossil infills and most of them are interpreted to be derived from passive infilling sediment that was not affected by feeding and excretion activities of the trace maker. (2) Comparing preservation from inside and outside of the trace fossils, the radiolarians from inside the trace fossil are much better preserved than those from outside. (3) Microfossils that were transported into the trace fossil within infill sediment were protected from subsequent burial compaction and diagenesis by preferential cementation to produce a concretion of the trace fossil, and this has enabled the siliceous microfossils to be relatively well-preserved. These results support the idea that trace fossils offer significant microfossil preservation potential. Trace fossils may also be considered as natural archives of valuable micropaleontological records that would usually be lost during burial, compaction and diagenetic processes. Taphonomic analysis of siliceous microfossils within the infills of trace fossils, such as <em>Tasselia ordamensis,</em> has the potential to reveal significant new paleontological insight from sedimentary rocks throughout the fossil record.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"82 ","pages":"Article 100754"},"PeriodicalIF":0.9,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139636762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nassellarian polycystine radiolarians observed in sediment traps from the southern Ionian Sea (Eastern Mediterranean)","authors":"Marie Cueille ,&nbsp;Taniel Danelian ,&nbsp;Koen Sabbe ,&nbsp;Mathias Meunier ,&nbsp;Elisavet Skampa ,&nbsp;Maria Triantaphyllou ,&nbsp;Alexandra Gogou","doi":"10.1016/j.revmic.2023.100753","DOIUrl":"10.1016/j.revmic.2023.100753","url":null,"abstract":"<div><p><span><span>Based on sediment traps moored in the southern Ionian Sea (Eastern Mediterranean), this paper documents nassellarian </span>radiolarian occurrences (54 species). Several taxa are reported and illustrated for the first time for the Mediterranean Sea (i.e., </span><em>Trisulcus triacanthus, Tricerapyris damaecornis, Archiperidium longispinum</em> and <em>Artostrobus joergenseni</em>). Emphasis was placed on the documentation of various ontogenetic stages for some of the encountered species. We also provide a review of the biogeographical distribution for all the confidently identified species, in order to shed light on the provenance of radiolarian fauna in the eastern Mediterranean Sea. Interestingly, despite a majority of warm-water radiolarians, we frequently encountered temperate to cold-water radiolarian species, such as <em>Artobotrys borealis, Artostrobus joergenseni</em> and <em>Archiperidium longispinum</em>.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"82 ","pages":"Article 100753"},"PeriodicalIF":0.9,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139395100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Orbitolina tibetica Cotter, 1929 and Tibetella tibetica Zhang, 1994: Taxonomic review of two ‘lost’ orbitolinids (Foraminifera) from the Lower Cretaceous of Tibet","authors":"Felix Schlagintweit ,&nbsp;François Le Coze","doi":"10.1016/j.revmic.2023.100748","DOIUrl":"10.1016/j.revmic.2023.100748","url":null,"abstract":"<div><p><em>Orbitolina tibetica</em><span><span> was described by Cotter in 1929 from the Lhasa terrane of the Tibetan </span>Himalaya, presumably from the Langshan Fm. Since Schroeder (1963), this species has been mainly included in the synonymy of </span><em>Palorbitolina lenticularis</em> (Blumenbach, 1805). New and detailed images from the type material of <em>O. tibetica</em> reveal that the illustrated specimens in the original description are undiagnostic except one axial section showing the megalospheric embryo, designated herein as lectotype. This section shows that <em>O. tibetica</em> Cotter, 1929 is identical to <em>Mesorbitolina parva</em> (Douglass, 1960) thus becoming its senior synonym and reinstating the new combination <em>Mesorbitolina tibetica</em> (Cotter, 1929) introduced by Zhang (1982, 1994). Consequently, the type-level of <em>M. tibetica</em><span> (Cotter) cannot be late Barremian-early Aptian, but has to be late Aptian. </span><em>Tibetella tibetica</em><span> Zhang, 1994 from the Albian Langshan Fm. with its tripartite embryo is redescribed and also reassigned to </span><em>Mesorbitolina</em> Schroeder, 1962. As there is neither a junior nor a senior synoym for this new combination, <em>Mesorbitolina zhangi</em> nomen novum is proposed as a replacement name for <em>Tibetella tibetica</em> Zhang, 1994 to avoid a secondary homonymy with <em>M. tibetica</em> (Cotter, 1929).</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100748"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135568109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foraminiferal distribution and biostratigraphy of the Lower Miocene Qom formation, north of Bijar, NW Iran","authors":"Mohsen Yazdi-Moghadam ,&nbsp;Mehdi Sarfi ,&nbsp;Mohammad Sharifi ,&nbsp;Mehrdad Naghusi","doi":"10.1016/j.revmic.2023.100747","DOIUrl":"10.1016/j.revmic.2023.100747","url":null,"abstract":"<div><p><span><span><span>This study is based on larger benthic foraminifera that dominate the Lower </span>Miocene </span>shelf carbonates<span> of the Qamcheqai section, NW Iran. During the time of deposition, the investigated area was positioned on the Eurasian side of the Tethyan Seaway between the Eastern and Western Tethys. Seven porcelaneous and hyaline perforated species were determined, including </span></span><em>Praebullalveolina curdica, Peneroplis evolutus, Androsina</em> cf. <em>diyarbakirensis, Sivasina egribucakensis, Miogypsina</em> cf. <em>intermedia, Operculina complanata</em>, and <em>Amphistegina bohdanowiczi</em>. The presence of <em>Miogypsina</em> cf. <em>intermedia</em>, and <em>Praebullalveolina curdica</em><span> allowed to correlate the assemblage with SBZ 25 Zone, indicating a Burdigalian age. The results of this study extend the paleogeographic distribution of the endemic taxa </span><em>Androsina</em> and <em>Sivasina</em> eastwards as far as Central Iran.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100747"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135248796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphogenesis of Balkhania balkhanica Mamontova, 1966 (benthic foraminifera) from Lower Cretaceous successions along the northern Tethyan margin (NE and Central Iran): Time and environmental control","authors":"Masoumeh Gheiasvand,&nbsp;Annachiara Bartolini","doi":"10.1016/j.revmic.2023.100749","DOIUrl":"10.1016/j.revmic.2023.100749","url":null,"abstract":"<div><p>Among large benthic foraminifera, <em>Balkhania</em> genus is one of the most valuable taxon that has been used to better constrain the biostratigraphy of the Lower Cretaceous successions along the Tethyan carbonate platforms. The species <em>Balkhania balkhanica</em> is considered as biostratigraphical index for the Barremian-Aptian interval. This study is focused on the <em>B. balkhanica</em>-bearing intervals of the Tirgan and Taft formations from two sections, deposited on the carbonate platform of the Iranian Tethyan margin (Kopet-Dagh Basin, NE Iran and Yazd Block, Central Iran). The age of the studied sections has already been determined in previous works. In present research, morphology and stratigraphical and ecological distribution of the recorded specimens are interpreted. According to the morphological changes, two morphotypes of <em>B. Balkhanica</em> have been introduced. Small-size morphotype is recorded in the Upper Valanginian to Upper Hauterivian interval of the Tirgan Formation. The Upper Barremian to Lower Aptian successions are mostly associated with larger sized specimens having a coarse quartz agglutinated wall, and named arenaceous morphotype. Their wall is in contrast to the Turkmenistan type specimens having a calcite microgranular-agglutinated wall. Inherent evolutionary factor suggests an evolutionary trend of this species from smaller to larger sized specimens during the Late Valanginian to Early Aptian. A preliminary study of the depositional environment also indicates an environmental control for this type of morphological variation. It suggests that the small-size morphotype mostly occurred in an under-stress shallow-water environment, while the larger size morphotype was associated with deeper and more stable outer-shelf environments.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100749"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135809618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upper Cretaceous (Turonian–Santonian) Haplophragmoides from IODP site U1512, Great Australian Bight","authors":"Erik Wolfgring ,&nbsp;Michael A. Kaminski ,&nbsp;Anna Waśkowska","doi":"10.1016/j.revmic.2023.100739","DOIUrl":"10.1016/j.revmic.2023.100739","url":null,"abstract":"<div><p><span>Results from the International Ocean Discovery Program (IODP) Site U1512 in the Great Australian Bight offer insights into climate immediately after the peak of the Cretaceous hothouse. Lower Turonian to </span>Santonian<span> deposits yield a unique high-resolution micropaleontological record of the Australo-Antarctic Gulf that is dominated by agglutinated foraminifera. The complex paleoenvironment at Site U1512 illustrates a constantly changing marine setting characterized by the interplay of runoff from the vast Ceduna River system to the north and varying degrees of influence of the Indian Ocean.</span></p><p>A common element in the agglutinated foraminiferal assemblage is the genus <em>Haplophragmoides,</em><span> which represents between 20 and 40% of the total benthic foraminiferal assemblage, and its occurrence seems particularly common in intervals with higher terrestrial influx. Like many agglutinated foraminiferal assemblages, the agglutinated taxa at Site U1512 suffer from preservational issues. In addition to effects during early diagenesis, like the degradation of organic cement, the delicate planispiral taxa especially experienced extensive deformation, which can affect the correct identification of taxonomically relevant features. Among the six species of </span><em>Haplophragmoides</em> that represent most of this genus at Site U1512, we identify and describe three new species: <em>H. petaliformis</em> n.sp., <em>H. tenellulus</em> n.sp.<em>,</em> and <em>H. antarcticus</em> n.sp.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100739"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124548981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Sinemurian and Early Pliensbachian Radiolaria from Mount Rettenstein (Northern Calcareous Alps, Austria). Part 2. Entactinaria and Spumellaria","authors":"Tim Cifer,&nbsp;Špela Goričan","doi":"10.1016/j.revmic.2023.100752","DOIUrl":"https://doi.org/10.1016/j.revmic.2023.100752","url":null,"abstract":"<div><p>On Mount Rettenstein (Northern Calcareous Alps, Austria) a 95-m-thick Lower Jurassic succession of grey siliceous limestone and marl allowed us to study well-preserved and diverse radiolarian assemblages. The succession crossing the Sinemurian–Pliensbachian boundary yielded seven productive radiolarian samples, five of which were assigned to the Upper Sinemurian and two to the Lower Pliensbachian. In this article, we present 24 species and nine genera belonging to the order Entactinaria, and 66 species and 27 genera to the order Spumellaria. One genus (<em>Tetractoma</em> Cifer nov. gen.) and six species are described as new: <em>Charlottalum austriacum</em> Cifer nov. sp., <em>Crucella optima</em> Cifer nov. sp., <em>Hexapyramis</em>? <em>sphaericus</em> Cifer nov. sp., <em>Paronaella triangularis</em> Cifer nov. sp., <em>Pseudoheliodiscus rotaformis</em> Cifer nov. sp., and <em>Tetractoma tollmanni</em> Cifer nov. gen. nov. sp. In the Sinemurian, by far the most abundant genus amongst either Spumellaria and Entactinaria is <em>Gorgansium</em>. The Pliensbachian samples are, on the other hand, dominated by the genera <em>Archaeocenosphaera</em> and <em>Praeconocaryomma</em>. Compiled stratigraphic and geographic ranges as well as synonymies, descriptions and remarks are provided.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100752"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0035159823000417/pdfft?md5=0e42d861d46df469b1647e734ddc4c57&pid=1-s2.0-S0035159823000417-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138549287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Reticulinella?-Mangashtia foraminiferal association: Characterisation of the (upper?) middle-?lower upper Turonian interval in the Sarvak Formation of SW Iran and its bearing upon Upper Cretaceous Arabian Plate sequence stratigraphy","authors":"Felix Schlagintweit ,&nbsp;Mohsen Yazdi-Moghadam ,&nbsp;Mike Simmons ,&nbsp;Yiwei Xu","doi":"10.1016/j.revmic.2023.100740","DOIUrl":"10.1016/j.revmic.2023.100740","url":null,"abstract":"<div><p><span><span>During the mid-Cretaceous the Arabian Plate underwent a major tectonically-driven stratigraphic reorganization, with the development of a major regional unconformity, often ascribed to the middle </span>Turonian<span>. However, evidence for the age calibration of this unconformity (e.g., from biostratigraphy) is limited. A previously undescribed assemblage of larger benthic foraminifera has been discovered in a section at Khormuj in the Coastal Fars region of the Iranian Zagros. This section lies in the uppermost Sarvak Formation, directly beneath the major unconformity surface. Dominant components of the assemblage are </span></span><em>Mangashtia viennoti</em> Henson, and <em>Reticulinella</em>? <em>kaeveri</em><span> Cherchi, Radoičić and Schroeder. Their presence places the uppermost Sarvak Formation at this locality in the age range (upper?) middle – ?lower upper Turonian, and in the context of evidence from other localities in the region it is most likely upper middle Turonian. This provides new constraint on the timing of the unconformity and stratigraphic organisation, and the tectonic events leading to its creation (e.g., forebulge creation related to ophiolite obduction). The presence of </span><em>R.</em>? <em>kaeveri</em><span><span> is reported for the first time from outside of the Mediterranean region and indicates that this taxon is useful for biostratigraphic calibration. As a result, </span>biozonation schemes for the upper Sarvak Formation can be updated.</span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"81 ","pages":"Article 100740"},"PeriodicalIF":0.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129300230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Paleozoic and Early Mesozoic radiolarians from chert conglomerates embedded in the Kaeng Raboet Formation (Upper Mesozoic continental red-bed), Kanchanaburi Province, western Thailand","authors":"Katsuo Sashida ,&nbsp;Panus Hong ,&nbsp;Parisa Nimnate ,&nbsp;Tsuyoshi Ito ,&nbsp;Kantanat Trakunweerayut ,&nbsp;Sirot Salyapongse ,&nbsp;Prinya Putthapiban","doi":"10.1016/j.revmic.2023.100728","DOIUrl":"https://doi.org/10.1016/j.revmic.2023.100728","url":null,"abstract":"<div><p><span>Continental clastic red-beds including red and fine- to medium-grained sandstone, pebbly sandstone, and conglomerates are distributed in the Sai Yok area of western Thailand. This rock sequence is known as the Jurassic Kaeng Raboet Formation by Thai geologists. A similar clastic rock<span> succession, approximately 150 m thick, outcropping at Wat Phu Toey, near Ban Tha Sao, was investigated for paleontological analysis. The lithostratigraphy of the sequence in this section consists of Units 1-3 in ascending order. Unit 1 is characterized by pebble-sized </span></span>chert<span><span><span> conglomerates, Unit 2 by medium-grained massive sandstone, and Unit 3 by fine-grained red sandstone and shale with ripple marks and cross-laminations. Several thin layers of chert conglomerate are intercalated in the lower parts of Units 2 and 3. We collected six chert conglomerate samples from this section and distinguished Tournaisian (Lower Carboniferous) to middle </span>Norian<span> (Upper Triassic) radiolarian-bearing chert clasts that have not been not separated as single clasts but treated as one sample. Although the preservation of radiolarians is generally poor, we identified 40 species belonging to 26 genera with one radiolarian<span> gen. et sp. indet. The exact age of the Kaeng Raboet Formation is still equivocal; however, we assigned the age of the red-bed to the Late Jurassic<span> to Early Cretaceous based on the presence of </span></span></span></span>Middle Jurassic<span> foraminifer-bearing limestone clasts in the limestone conglomerate embedded in equivalent formations. The present chert conglomerate, including radiolarian-bearing chert clasts is interpreted to have been derived from the grained siliceous rock bodies of the Mae Sariang Zone and deposited in an alluvial depositional basin and braided river system during the Late Jurassic to Early Cretaceous.</span></span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"80 ","pages":"Article 100728"},"PeriodicalIF":0.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49852046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecologically distinct myodocope ostracod faunas from a single horizon in the late Silurian of Spain","authors":"Vincent Perrier ,&nbsp;Gwendal Perrichon ,&nbsp;Félix Nesme ,&nbsp;Helga Groos-Uffenorde ,&nbsp;Saturnino Lorenzo ,&nbsp;Juan Carlos Gutiérrez-Marco","doi":"10.1016/j.revmic.2023.100729","DOIUrl":"https://doi.org/10.1016/j.revmic.2023.100729","url":null,"abstract":"<div><p><span><span>Silurian myodocopes have been demonstrated to be the pioneer pelagic </span>ostracods<span>. Their ecological shift into the water column, during the middle Silurian (Wenlock-Ludlow), is now well documented from sites around the world, but the evolution of this fauna during the late Silurian (Pridoli) remains little studied. We recognise, for the first time, two ecologically distinct myodocope ostracod faunas from the same late Pridoli horizon (possibly ?</span></span><em>Wolynograptus bouceki</em> - <em>Skalograptus transgrediens</em><span> biozones) of southern Spain (Alcaracejos, province of Córdoba). One fauna, associated with black shales, comprises five species belonging to three myodocope families (bolbozoids, entomozoids and cypridinids). The other fauna, recovered from large dark-reddish calcareous nodules and associated with the planktonic crinoid </span><em>Scyphocrinites elegans</em>, comprises seven myodocope species belonging to the same three families and includes one new species, <em>Calocaria callundosa</em> sp. nov. Although the shale and nodule faunas have two species in common, they are clearly different in terms of diversity, abundance and size of the specimens. The discrepancies between these two assemblages could either be explained by sampling or taphonomic bias, or because they represent faunas with different ecologies. In the latter hypothesis, the myodocope association in the shales could represent the “background” planktonic fauna, while the fauna in the nodules could have lived in the water column in the vicinity of the <em>Scyphocrinites</em> “floating islands”, or scavenge around the dead crinoids on the sea floor. These two diverse assemblages also allow discussions on the temporal and palaeogeographical distributions of these late Silurian myodocope ostracods.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":"80 ","pages":"Article 100729"},"PeriodicalIF":0.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49808688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}