Journal of Micropalaeontology最新文献

{"title":"Paleoenvironmental changes related to the variations of the sea-ice cover during the Late Holocene in an Antarctic fjord (Edisto Inlet, Ross Sea) inferred by foraminiferal association","authors":"Giacomo Galli, Caterina Morigi, Romana Melis, Alessio Di Roberto, Tommaso Tesi, Fiorenza Torricella, Leonardo Langone, Patrizia Giordano, Ester Colizza, Lucilla Capotondi, Andrea Gallerani, Karen Gariboldi","doi":"10.5194/jm-42-95-2023","DOIUrl":"https://doi.org/10.5194/jm-42-95-2023","url":null,"abstract":"Abstract. TR17-08, a marine sedimentary core (14.6 m), was collected during 2017 from the Edisto Inlet (Ross Sea, Antarctica), a small fjord near Cape Hallett. The core is characterized by expanded laminated sedimentary sequences making it suitable for studying submillennial processes during the Early Holocene. By studying different well-known foraminifera species (Globocassidulina biora, G. subglobosa, Trifarina angulosa, Nonionella iridea, Epistominella exigua, Stainforthia feylingi, Miliammina arenacea, Paratrochammina bartrami and Portatrochammina antarctica), we were able to identify five different foraminiferal assemblages over the last ∼ 2000 years BP. Comparison with diatom assemblages and other geochemical proxies retrieved from nearby sediment cores in the Edisto Inlet (BAY05-20 and HLF17-1) made it possible to distinguish three different phases characterized by different environmental settings: (1) a seasonal phase (from 2012 to 1486 years BP) characterized by the dominance of calcareous species, indicating a seasonal opening of the inlet by more frequent events of melting of the sea-ice cover during the austral summer and, in general, a higher-productivity, more open and energetic environment; (2) a transitional phase (from 1486 to 696 years BP) during which the fjord experienced less extensive sea-ice melting, enhanced oxygen-poor conditions and carbonate dissolution conditions, indicated by the shifts from calcareous-dominated association to agglutinated-dominated association probably due to a freshwater input from the retreat of three local glaciers at the start of this period; and (3) a cooler phase (from 696 years BP to present) during which the sedimentation rate decreased and few to no foraminiferal specimens were present, indicating ephemeral openings or a more prolonged cover of the sea ice during the austral summer, affecting the nutrient supply and the sedimentation regime.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135741052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artifacts resembling Ediacaran or Cambrian fossils: how to identify them and avoid their generation","authors":"T.F. Toniolo, J. Leme, Dermeval A. Carmo, T. Fairchild, L. Morais, R. Trindade","doi":"10.5194/jm-42-83-2023","DOIUrl":"https://doi.org/10.5194/jm-42-83-2023","url":null,"abstract":"Abstract. The generation of artifacts during sample preparation must be\u0000considered in paleobiological studies, particularly during the Ediacaran and\u0000Cambrian, since such artifacts can assume forms similar to those of\u0000cloudinids and other problematic taxa commonly described in samples from\u0000these systems. Chemical reactions between hydrogen peroxide and sulfides\u0000from the samples can lead to the formation of tubular and vase-shaped\u0000structures. The visual description alone does not allow a conclusion about whether their\u0000origin is organic or inorganic. In these cases, chemical composition and\u0000ultrastructure analysis are tools that help to distinguish artifacts from\u0000bona fide fossils. Scanning electron microscopy can be successfully employed\u0000to characterize and differentiate fossils from artifacts. The presence or\u0000absence of these structures in thin sections is also an essential piece of\u0000information to discuss their biogenicity. Furthermore, not using hydrogen\u0000peroxide avoids the risk of formation of the artifacts described here.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"1 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41584711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Globigerinoides rublobatus – a new species of Pleistocene planktonic foraminifera","authors":"Marcin Latas, P. Pearson, C. R. Poole, Alessio Fabbrini, B. Wade","doi":"10.5194/jm-42-57-2023","DOIUrl":"https://doi.org/10.5194/jm-42-57-2023","url":null,"abstract":"Abstract. We describe Globigerinoides rublobatus n. sp., a new morphospecies of fossil\u0000planktonic foraminifera, from the Pleistocene sediments (∼810 ka) of the Indian Ocean and Pacific Ocean. We use image analysis and morphometry\u0000of 860 specimens from International Ocean Discovery Program Site U1483 in\u0000the tropical Indian Ocean to document morphological variability in the new\u0000morphospecies and related taxa, and we also report it from Pacific Ocean\u0000Site U1486 for the first time. The new morphospecies combines\u0000characteristics typical of Globigerinoides conglobatus (Brady, 1879) and Globigerinoides ruber (d'Orbigny, 1839), with which\u0000it co-occurs, but is distinct from both. Morphometric data indicate that G. rublobatus n.\u0000sp. is closer to G. conglobatus, potentially signalling an evolutionary affinity. We\u0000find that Globigerinoides rublobatus n. sp. occurs as two variants, a pigmented (pink) form and a\u0000non-pigmented (white) form. The non-pigmented forms are on average\u0000∼50 % larger than the pigmented forms. This is so far only\u0000the third instance of fossil planktonic foraminifera known to exhibit this\u0000pink pigmentation. We regard the pink and white forms as variants of a\u0000single morphospecies and suggest the pink form may represent a later\u0000evolutionary adaptation.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45488848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities","authors":"L. Thöle, P. Nooteboom, Suning Hou, Rujian Wang, Senyan Nie, E. Michel, I. Sauermilch, F. Marret, F. Sangiorgi, P. Bijl","doi":"10.5194/jm-42-35-2023","DOIUrl":"https://doi.org/10.5194/jm-42-35-2023","url":null,"abstract":"Abstract. Dinoflagellate cyst assemblages present a valuable proxy to infer\u0000paleoceanographic conditions, yet factors influencing geographic\u0000distributions of species remain largely unknown, especially in the Southern\u0000Ocean. Strong lateral transport, sea-ice dynamics, and a sparse and uneven\u0000geographic distribution of surface sediment samples have limited the use of\u0000dinocyst assemblages as a quantitative proxy for paleo-environmental\u0000conditions such as sea surface temperature (SST), nutrient concentrations,\u0000salinity, and sea ice (presence). In this study we present a new set of\u0000surface sediment samples (n=66) from around Antarctica, doubling the\u0000number of Antarctic-proximal samples to 100 (dataset wsi_100)\u0000and increasing the total number of Southern Hemisphere samples to 655\u0000(dataset sh_655). Additionally, we use modelled ocean\u0000conditions and apply Lagrangian techniques to all Southern Hemisphere sample\u0000stations to quantify and evaluate the influence of lateral transport on the\u0000sinking trajectory of microplankton and, with that, to the inferred ocean\u0000conditions. k-means cluster analysis on the wsi_100 dataset\u0000demonstrates the strong affinity of Selenopemphix antarctica with sea-ice presence and of Islandinium spp. with\u0000low-salinity conditions. For the entire Southern Hemisphere, the k-means\u0000cluster analysis identifies nine clusters with a characteristic assemblage.\u0000In most clusters a single dinocyst species dominates the assemblage. These\u0000clusters correspond to well-defined oceanic conditions in specific Southern\u0000Ocean zones or along the ocean fronts. We find that, when lateral transport\u0000is predominantly zonal, the environmental parameters inferred from the sea\u0000floor assemblages mostly correspond to those of the overlying ocean surface.\u0000In this case, the transport factor can thus be neglected and will not\u0000represent a bias in the reconstructions. Yet, for some individual sites,\u0000e.g. deep-water sites or sites under strong-current regimes, lateral\u0000transport can play a large role. The results of our study further constrain\u0000environmental conditions represented by dinocyst assemblages and the\u0000location of Southern Ocean frontal systems.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44826235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to Fordham and Welter-Schultes's comment on “Taxonomic review of living planktonic foraminifera” by Brummer and Kučera (2022)","authors":"M. Kučera, G. Brummer","doi":"10.5194/jm-42-33-2023","DOIUrl":"https://doi.org/10.5194/jm-42-33-2023","url":null,"abstract":"<jats:p>\u0000 </jats:p>","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44245679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comment on “Taxonomic review of living planktonic foraminifera” by Brummer and Kučera (2022)","authors":"B. Fordham, F. Welter-Schultes","doi":"10.5194/jm-42-31-2023","DOIUrl":"https://doi.org/10.5194/jm-42-31-2023","url":null,"abstract":"<jats:p>\u0000 </jats:p>","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48047831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Holocene pteropod distribution across the base of the south-eastern Mediterranean margin: the importance of the > 63 µm fraction","authors":"V. Beccari, A. Almogi‐Labin, D. Basso, G. Panieri, Y. Makovsky, I. Hajdas, S. Spezzaferri","doi":"10.5194/jm-42-13-2023","DOIUrl":"https://doi.org/10.5194/jm-42-13-2023","url":null,"abstract":"Abstract. Euthecosomata pteropods were analysed in core sediments\u0000collected\u0000in the framework of the 2016 EUROFLEETS2 SEMSEEP cruise, offshore of Israel,\u0000in the eastern Mediterranean Sea. The investigated cores were retrieved in a\u0000deep-sea coral area at 690 m depth, an actively methane-seeping pockmark\u0000area at 1038 m depth, and a deep-sea channel area at 1310 m water depth.\u0000We\u0000identified and documented the pteropod species belonging to the families\u0000Heliconoididae, Limacinidae, Creseidae, Cavoliniidae, Cliidae, and Hyalocylidae\u0000and to some heteropods. Our study highlights the importance of investigating\u0000pteropods in the size fractions > 63 µm instead of\u0000the\u0000> 125 µm only. In particular, neglecting the small\u0000size\u0000fraction may result in a remarkable (up to 50 %–60 %) underestimation of the\u0000relative abundance of the epipelagic species Creseis acicula and\u0000Creseis conica and the mesopelagic\u0000species Heliconoides inflatus. This may significantly affect\u0000palaeoenvironmental reconstructions.\u0000The observed presence of tropical species supports the suggestion that the\u0000eastern Mediterranean is a refugium for these species. This study provides\u0000a\u0000basic benchmark for the late Holocene evolution of pteropod and heteropod distribution over 5800–5300 cal BP across the base of the south-eastern Levantine margin.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43417457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting Early Jurassic Biscutaceae: Similiscutum giganteum sp. nov.","authors":"Samuel Mailliot, E. Mattioli, Micaela Chaumeil Rodríguez, B. Pittet","doi":"10.5194/jm-42-1-2023","DOIUrl":"https://doi.org/10.5194/jm-42-1-2023","url":null,"abstract":"Abstract. A large, broadly elliptical coccolith of the genus Similiscutum (Biscutaceae)\u0000was observed in sediments dated from the Lower Jurassic (upper Pliensbachian\u0000to Toarcian) coming from different localities of western Tethys, namely\u0000Portugal (Lusitanian Basin), France (Causses and Paris basins) and Spain\u0000(Subbetic area). This form is quite easy to find in the Toarcian GSSP (Global Stratotype Section and Point) of\u0000Peniche (Portugal), where the holotype has been described. More than 100 specimens of Similiscutum were digitally captured using a CCD camera, including\u0000this large form and two other related species, Similiscutum finchii and Similiscutum novum. The length and width of\u0000the coccoliths and the length and width of their central area were measured,\u0000and biometric analyses were performed. Results show that this large\u0000morphotype of Similiscutum is well characterized and easily differentiable by its size\u0000and morphology from the species S. finchii and S. novum, which are characterized by a similar\u0000extinction pattern in optical-microscope crossed polars . On the basis of\u0000combined differences in size and in central-area shape and structure,\u0000Similiscutum giganteum sp. nov. is introduced here. (Plant Fossil Names Registry no.: PFN003067;\u0000Act LSID: urn:lsid:plantfossilnames.org:act:3067).\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43832155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial intelligence applied to the classification of eight middle Eocene species of the genus Podocyrtis (polycystine radiolaria)","authors":"V. Carlsson, T. Danelian, Pierre Boulet, P. Devienne, Aurelien Laforge, J. Renaudie","doi":"10.5194/jm-41-165-2022","DOIUrl":"https://doi.org/10.5194/jm-41-165-2022","url":null,"abstract":"Abstract. This study evaluates the application of artificial intelligence (AI) to the automatic\u0000classification of radiolarians and uses as an example eight distinct\u0000morphospecies of the Eocene radiolarian genus Podocyrtis, which are part of three\u0000different evolutionary lineages and are useful in biostratigraphy. The\u0000samples used in this study were recovered from the equatorial Atlantic (ODP\u0000Leg 207) and were supplemented with some samples coming from the North\u0000Atlantic and Indian Oceans. To create an automatic classification tool,\u0000numerous images of the investigated species were needed to train a\u0000MobileNet convolutional neural network entirely coded in Python. Three\u0000different datasets were obtained. The first one consists of a mixture of\u0000broken and complete specimens, some of which sometimes appear blurry. The\u0000second and third datasets were leveled down into two further steps, which\u0000excludes broken and blurry specimens while increasing the quality. The\u0000convolutional neural network randomly selected 85 % of all specimens for\u0000training, while the remaining 15 % were used for validation. The MobileNet\u0000architecture had an overall accuracy of about 91 % for all datasets.\u0000Three predicational models were thereafter created, which had been trained\u0000on each dataset and worked well for classification of Podocyrtis coming from the\u0000Indian Ocean (Madingley Rise, ODP Leg 115, Hole 711A) and the western North\u0000Atlantic Ocean (New Jersey slope, DSDP Leg 95, Hole 612 and Blake Nose, ODP\u0000Leg 171B, Hole 1051A). These samples also provided clearer images since they\u0000were mounted with Canada balsam rather than Norland epoxy. In spite of some\u0000morphological differences encountered in different parts of the world's\u0000oceans and differences in image quality, most species could be correctly\u0000classified or at least classified with a neighboring species along a\u0000lineage. Classification improved slightly for some species by cropping\u0000and/or removing background particles of images which did not segment\u0000properly in the image processing. However, depending on cropping or\u0000background removal, the best result came from the predictive model trained on\u0000the normal stacked dataset consisting of a mixture of broken and complete\u0000specimens.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44380361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysing planktonic foraminiferal growth in three dimensions with foram3D: an R package for automated trait measurements from CT scans","authors":"A. Brombacher, Alex Searle-Barnes, Wenshu Zhang, T. Ezard","doi":"10.5194/jm-41-149-2022","DOIUrl":"https://doi.org/10.5194/jm-41-149-2022","url":null,"abstract":"Abstract. Foraminifera are one of the few taxa that preserve their\u0000entire ontogeny in their fossilised remains. Revealing this ontogeny through\u0000micro-computed tomography (CT) of fossil planktonic foraminifera has greatly\u0000improved our understanding of their life history and allows accurate\u0000quantification of total shell volume, growth rates and developmental\u0000constraints throughout an individual's life. Studies using CT scans\u0000currently mainly focus on chamber size, but the wealth of three-dimensional\u0000data generated by CT scans has the potential to reconstruct complete growth\u0000trajectories. Here we present an open-source R package to analyse growth in\u0000three-dimensional space. Using only the centroid xyz coordinates of every\u0000chamber, the functions determine the growth sequence and check that chambers\u0000are in the correct order. Once the order of growth has been verified, the\u0000functions calculate distances and angles between subsequent chambers,\u0000determine the total number of whorls and the number of chambers in the final\u0000whorl at the time each chamber was built, and, for the first time, quantify\u0000trochospirality. The applications of this package will enable repeatable\u0000analysis of large data sets and quantification of key taxonomic traits and\u0000ultimately provide new insights into the effects of ontogeny on evolution.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49447846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}