Geise de S. Anjos Zerfass, Claudia G. Cetean, Lucas del Mouro, Christiano Ng, Henrique Zerfass, A. Camargo
Microfossils have been found in most of the Mesozoic basins of Brazil, allowing the establishment of important biozones. Despite being recognized for more than half century in the Barremian from the Reconcavo Basin, the taxonomy of the benthic foraminifera remained unsolved likewise its paleoenviromental implications. In this study, we have applied 2D and 3D imaging techniques to resolve this issue and have identified two agglutinated foraminiferal genera (Glomospirella and Paratrochamminoides) and a new species Paratrochamminoides kaminskii sp. nov. Moreover, based on the taxonomy, few paleoenvironmental insights on the foraminifera-bearing strata are discussed. The occurrence of the typically shallow marine species Glomospirella arctica in the studied section, does not allow the proposition of a marine ingression, since it is not supported by a marine/ transitional association of microfossils. On the other hand, the hypothesis of transport of foraminifera by birds (avian zoocoria) is plausible, although there are no further elements to corroborate it.
{"title":"Agglutinated Foraminifera from the Barremian continental rift section of the Reconcavo Basin, Brazil: a microfossil enigma","authors":"Geise de S. Anjos Zerfass, Claudia G. Cetean, Lucas del Mouro, Christiano Ng, Henrique Zerfass, A. Camargo","doi":"10.47894/mpal.68.2.03","DOIUrl":"https://doi.org/10.47894/mpal.68.2.03","url":null,"abstract":"Microfossils have been found in most of the Mesozoic basins of Brazil, allowing the establishment of important biozones. Despite being recognized for more than half century in the Barremian from the Reconcavo Basin, the taxonomy of the benthic foraminifera remained unsolved likewise its paleoenviromental implications. In this study, we have applied 2D and 3D imaging techniques to resolve this issue and have identified two agglutinated foraminiferal genera (Glomospirella and Paratrochamminoides) and a new species Paratrochamminoides kaminskii sp. nov. Moreover, based on the taxonomy, few paleoenvironmental insights on the foraminifera-bearing strata are discussed. The occurrence of the typically shallow marine species Glomospirella arctica in the studied section, does not allow the proposition of a marine ingression, since it is not supported by a marine/ transitional association of microfossils. On the other hand, the hypothesis of transport of foraminifera by birds (avian zoocoria) is plausible, although there are no further elements to corroborate it.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Since their origin in the Ordovician, ostracods have radiated to several different aquatic and even semiterrestrial environments, evolving under influence of both extrinsic (ecological) and intrinsic (genetic) factors. The deep ocean does not constitute an exception to these controls, no matter how different the concept of deep-sea might be among students of Paleozoic and post-Paleozoic ostracods. Once integrated to the bathybic biotas (i.e., from bathyal to abyssal depths, including guyots), ostracods followed a particular pattern of diversification and dispersal in response to climatic and tectonic events.
{"title":"The \"Bradleya problem\", the spearhead of ostracod-based paleoceanography - contribution and outcomes","authors":"C. T. Bergue, M. Kaminski","doi":"10.47894/mpal.68.3.01","DOIUrl":"https://doi.org/10.47894/mpal.68.3.01","url":null,"abstract":"Since their origin in the Ordovician, ostracods have radiated to several different aquatic and even semiterrestrial environments, evolving under influence of both extrinsic (ecological) and intrinsic (genetic) factors. The deep ocean does not constitute an exception to these controls, no matter how different the concept of deep-sea might be among students of Paleozoic and post-Paleozoic ostracods. Once integrated to the bathybic biotas (i.e., from bathyal to abyssal depths, including guyots), ostracods followed a particular pattern of diversification and dispersal in response to climatic and tectonic events.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Roy, Amit K. Ghosh, A. K. Bhaumik, A. Chakraborty, S. Sensarma, S. Saxena
The present study has been carried out from the NGHP sediment core (NGHP-01-17A) of northeast Indian Ocean on different siliceous microfossils represented by diatoms and radiolarians along with calcareous nannofossils. Samples from the bottommost subunit Ic of the sediment core (684.09 mbsf to 369.62 mbsf) have been analysed. This contribution is the first comprehensive account on the Tortonian diatom assemblages from the offshore of northeast Indian Ocean that has been integrated with the radiolarian zonations. For determining the relative age of the sequence more precisely the obtained dataset also have been correlated to the calcareous nannofossil zones and eventually an attempt has been made to establish an integrated biostratigraphy. Detailed taxonomic analysis of the diatoms reveals the presence of 118 diatom taxa belonging to 49 genera. Three diatom biozones have been determined using CONISS cluster analysis. Based on the index radiolarian taxa in the studied samples, the entire sequence is assignable to RN6, RN7 and RN8 zones. The samples also contain stratigraphic marker taxa of calcareous nannofossils that allow identifying NN9, NN10 and NN11 zones corresponding to CNM13 - CNM16 zones. The ages of the bottommost and topmost sample of the analysed section of the core have been estimated < 10.49 Ma and > 7.39 Ma respectively. To estimate the sedimentation rate an age-depth model has been proposed using diatom, radiolarian and calcareous nannofossil events. All the microfossil assemblages of the present study have been correlated with the known assemblages of late Miocene, specifically Tortonian from DSDP, ODP, IODP expeditions and onshore sediments of Indian Ocean as well as equatorial Pacific Ocean. Diversity analysis has been carried out to quantitatively estimate the diversity and dominance of the diatom taxa. Planktic/benthic ratio of the diatoms has been calculated to evaluate the water depth.
{"title":"Diatom assemblages from the Tortonian of northeast Indian Ocean (NGHP- 01- 17A): correlation with significant radiolarian and calcareous nannofossil events","authors":"L. Roy, Amit K. Ghosh, A. K. Bhaumik, A. Chakraborty, S. Sensarma, S. Saxena","doi":"10.47894/mpal.68.1.03","DOIUrl":"https://doi.org/10.47894/mpal.68.1.03","url":null,"abstract":"The present study has been carried out from the NGHP sediment core (NGHP-01-17A) of northeast Indian Ocean on different siliceous microfossils represented by diatoms and radiolarians along with calcareous nannofossils. Samples from the bottommost subunit Ic of the sediment core (684.09 mbsf to 369.62 mbsf) have been analysed. This contribution is the first comprehensive account on the Tortonian diatom assemblages from the offshore of northeast Indian Ocean that has been integrated with the radiolarian zonations. For determining the relative age of the sequence more precisely the obtained dataset also have been correlated to the calcareous nannofossil zones and eventually an attempt has been made to establish an integrated biostratigraphy. Detailed taxonomic analysis of the diatoms reveals the presence of 118 diatom taxa belonging to 49 genera. Three diatom biozones have been determined using CONISS cluster analysis. Based on the index radiolarian taxa in the studied samples, the entire sequence is assignable to RN6, RN7 and RN8 zones. The samples also contain stratigraphic marker taxa of calcareous nannofossils that allow identifying NN9, NN10 and NN11 zones corresponding to CNM13 - CNM16 zones. The ages of the bottommost and topmost sample of the analysed section of the core have been estimated < 10.49 Ma and > 7.39 Ma respectively. To estimate the sedimentation rate an age-depth model has been proposed using diatom, radiolarian and calcareous nannofossil events. All the microfossil assemblages of the present study have been correlated with the known assemblages of late Miocene, specifically Tortonian from DSDP, ODP, IODP expeditions and onshore sediments of Indian Ocean as well as equatorial Pacific Ocean. Diversity analysis has been carried out to quantitatively estimate the diversity and dominance of the diatom taxa. Planktic/benthic ratio of the diatoms has been calculated to evaluate the water depth.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Hart, J. K. Fisher, C. Smart, Rebecca Speers, D. Wall-Palmer
The Soufrière Hills Volcano, on the island of Montserrat, has an eruption history spanning over 2 million years. During this time the volcano has undergone multiple eruptions with intervening periods of low activity or dormancy. The most recent activity began in 1995 and has seen a series of major eruptive events. One of the most recent of these, and the focus of this study, occurred on the 20th May 2006. This major dome collapse produced 90 million m3 of volcanic material in only 3 hours, propelling ash clouds through the air and pyroclastic flows down the side of the volcano and into the sea. In this study of benthic foraminifera, cores from four sites off-shore Montserrat are analysed, including those collected from a location within the path of the 2006 ash cloud, around 10 km west of the Montserrat coast. In this area, one core contained 6-7 cm of ash overlying hemipelagic sediments. Volcanic ash is present in two distinct layers, one 3 cm layer produced by the 2006 eruption and the other, 3-4 cm layer, from an earlier eruption in 2003. Other cores were collected from areas unaffected by recent ash fall deposits and provide a base line for comparisons within the affected areas. To the east and south-east of Montserrat there is a different situation as this is the direction of travel of massive pyroclastic flows down the Tar Valley and the impact on the sea floor is more dramatic. There are also two extinct volcanic centres that allow the investigation of sea floor re-colonization on different time scales. The sites to the west of Montserrat record rapid colonization by benthic foraminifera of opportunistic taxa, comparable to that seen near Mt Pinatubo in the South China Sea while the sites to the east record a slower pattern of re-colonization by a wider spectrum of taxa, similar to that recorded at Deception Island in the Southern Ocean, with different benthic taxa performing the pioneering role.
{"title":"Re-colonization of hostile environments by benthic foraminifera: an example from Montserrat, Lesser Antilles Volcanic Arc","authors":"M. Hart, J. K. Fisher, C. Smart, Rebecca Speers, D. Wall-Palmer","doi":"10.47894/mpal.68.1.01","DOIUrl":"https://doi.org/10.47894/mpal.68.1.01","url":null,"abstract":"The Soufrière Hills Volcano, on the island of Montserrat, has an eruption history spanning over 2 million years. During this time the volcano has undergone multiple eruptions with intervening periods of low activity or dormancy. The most recent activity began in 1995 and has seen a series of major eruptive events. One of the most recent of these, and the focus of this study, occurred on the 20th May 2006. This major dome collapse produced 90 million m3 of volcanic material in only 3 hours, propelling ash clouds through the air and pyroclastic flows down the side of the volcano and into the sea. In this study of benthic foraminifera, cores from four sites off-shore Montserrat are analysed, including those collected from a location within the path of the 2006 ash cloud, around 10 km west of the Montserrat coast. In this area, one core contained 6-7 cm of ash overlying hemipelagic sediments. Volcanic ash is present in two distinct layers, one 3 cm layer produced by the 2006 eruption and the other, 3-4 cm layer, from an earlier eruption in 2003. Other cores were collected from areas unaffected by recent ash fall deposits and provide a base line for comparisons within the affected areas. To the east and south-east of Montserrat there is a different situation as this is the direction of travel of massive pyroclastic flows down the Tar Valley and the impact on the sea floor is more dramatic. There are also two extinct volcanic centres that allow the investigation of sea floor re-colonization on different time scales. The sites to the west of Montserrat record rapid colonization by benthic foraminifera of opportunistic taxa, comparable to that seen near Mt Pinatubo in the South China Sea while the sites to the east record a slower pattern of re-colonization by a wider spectrum of taxa, similar to that recorded at Deception Island in the Southern Ocean, with different benthic taxa performing the pioneering role.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anna B. Joest, Hisayo Okahashi, A. Ostmann, P. Martínez-Arbizu, J. Svavarsson, S. Brix, M. Yasuhara
Presented here is an illustrated checklist of benthic marine Ostracoda (Crustacea) recorded from Recent surface sediments of the sub-polar North Atlantic Ocean (SPNA). It presents 142 species (and species groups) belonging to 62 genera from 41 sampling sites collected from the water depths of 144–2749 m.We provide census data with scanning electron microscope images of representative specimens of most species, as well as geographical and bathymetrical distribution maps of selected species and genera. Samples from the Nordic seas (i.e., Greenland Sea, Norwegian Sea), as well as North Atlantic proper waters (i.e., Irminger Sea, Iceland Sea) are included. The bathymetry covers shelf to continental rise surface sediments from the Irminger Basin, the Iceland Basin, the Iceland Plateau, the Denmark Strait, the Faeroe-Shetland Channel, the Iceland-Faeroe Ridge, the Reykjanes Ridge, and the Faeroe Plateau. The data presented here is an important taxonomic and biogeographical baseline of the SPNA benthic ostracod fauna.
{"title":"Recent deep-sea ostracods of the sub-polar North Atlantic Ocean","authors":"Anna B. Joest, Hisayo Okahashi, A. Ostmann, P. Martínez-Arbizu, J. Svavarsson, S. Brix, M. Yasuhara","doi":"10.47894/mpal.68.3.07","DOIUrl":"https://doi.org/10.47894/mpal.68.3.07","url":null,"abstract":"Presented here is an illustrated checklist of benthic marine Ostracoda (Crustacea) recorded from Recent surface sediments of the sub-polar North Atlantic Ocean (SPNA). It presents 142 species (and species groups) belonging to 62 genera from 41 sampling sites collected from the water depths of 144–2749 m.We provide census data with scanning electron microscope images of representative specimens of most species, as well as geographical and bathymetrical distribution maps of selected species and genera. Samples from the Nordic seas (i.e., Greenland Sea, Norwegian Sea), as well as North Atlantic proper waters (i.e., Irminger Sea, Iceland Sea) are included. The bathymetry covers shelf to continental rise surface sediments from the Irminger Basin, the Iceland Basin, the Iceland Plateau, the Denmark Strait, the Faeroe-Shetland Channel, the Iceland-Faeroe Ridge, the Reykjanes Ridge, and the Faeroe Plateau. The data presented here is an important taxonomic and biogeographical baseline of the SPNA benthic ostracod fauna.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A partial skeleton of a blue or fin whale, estimated to have been 16.5 m in length and thought to have been lying on the seafloor for less than 10 years, was observed at a depth of 1288 m off western Vancouver Island, British Columbia, Canada (48.68 N, 126.84 W). Four push cores were taken at the site, three (15-26 cm in length) directly under caudal vertebrae and one 18 cm long, considered a reference, 15 m away, in order to characterize changes in the benthic foraminiferal assemblage due to the whale-fall. A Q-mode cluster analysis identified four groupings, separating the surface and deeper samples of both the whale-fall and reference cores. The results of a metric multi-dimensional scaling plot and permutational multivariate analysis of variance test of the surface samples also suggest there was a significant difference between the whale-fall and reference core benthic foraminiferal faunas. No endemic species were recovered. Downcore samples below 6 cm in the whale-fall and reference cores were characterized by common Uvigerina peregrina, Pseudoparrella pacifica, Bolivina spissa, Bulimina striata, and Takayanagia delicata. In contrast, Cassidulinoides parkeriana, which typically is a minor component of benthic foraminiferal assemblages, dominated the upper 6 cm of the whale-fall cores, whereas the low oxygen-tolerant species T. delicata dominated the same interval in the reference core. The dramatic increase in abundance of C. parkeriana in the upper sediments below this whale-fall, as well as at the Torishima Seamount whale-fall site off Japan, indicate that it is an opportunistic species well adapted to taking advantage of unpredictable and highly localized tropic windfalls such as whale-falls. To our knowledge, this is the first benthic foraminiferal species shown to increase dramatically in abundance in the presence of a whale-fall. Additionally, modern fragments of whale bones occurring as deep as 12 to 15 cm downcore at the western Vancouver Island site demonstrate the effect of bioturbation by invertebrate scavengers that consume whale carcasses, indicating that detailed biostratigraphic records below whale-falls should be interpreted with caution.
{"title":"Affinity of the benthic foraminifer Cassidulinoides parkeriana (Brady) for whale-falls: evidence from off western Vancouver Island, British Columbia, Canada","authors":"M. McGann, C. Paull","doi":"10.47894/mpal.68.6.03","DOIUrl":"https://doi.org/10.47894/mpal.68.6.03","url":null,"abstract":"A partial skeleton of a blue or fin whale, estimated to have been 16.5 m in length and thought to have been lying on the seafloor for less than 10 years, was observed at a depth of 1288 m off western Vancouver Island, British Columbia, Canada (48.68 N, 126.84 W). Four push cores were taken at the site, three (15-26 cm in length) directly under caudal vertebrae and one 18 cm long, considered a reference, 15 m away, in order to characterize changes in the benthic foraminiferal assemblage due to the whale-fall. A Q-mode cluster analysis identified four groupings, separating the surface and deeper samples of both the whale-fall and reference cores. The results of a metric multi-dimensional scaling plot and permutational multivariate analysis of variance test of the surface samples also suggest there was a significant difference between the whale-fall and reference core benthic foraminiferal faunas. No endemic species were recovered. Downcore samples below 6 cm in the whale-fall and reference cores were characterized by common Uvigerina peregrina, Pseudoparrella pacifica, Bolivina spissa, Bulimina striata, and Takayanagia delicata. In contrast, Cassidulinoides parkeriana, which typically is a minor component of benthic foraminiferal assemblages, dominated the upper 6 cm of the whale-fall cores, whereas the low oxygen-tolerant species T. delicata dominated the same interval in the reference core. The dramatic increase in abundance of C. parkeriana in the upper sediments below this whale-fall, as well as at the Torishima Seamount whale-fall site off Japan, indicate that it is an opportunistic species well adapted to taking advantage of unpredictable and highly localized tropic windfalls such as whale-falls. To our knowledge, this is the first benthic foraminiferal species shown to increase dramatically in abundance in the presence of a whale-fall. Additionally, modern fragments of whale bones occurring as deep as 12 to 15 cm downcore at the western Vancouver Island site demonstrate the effect of bioturbation by invertebrate scavengers that consume whale carcasses, indicating that detailed biostratigraphic records below whale-falls should be interpreted with caution.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Self‐Trail, D. Watkins, J. Pospichal, E. L. Seefelt
The genus Hornibrookina consists of enigmatic calcareous nannofossils that first appeared shortly after the K-Pg mass extinction. Due to their relative paucity in most published sections, specimens of this genus have not been previously studied in detail and their paleobiogeographic preferences and evolutionary history have been poorly understood. Biostratigraphic and morphometric analyses of Hornibrookina specimens from outcrops and cores from the Atlantic Ocean, the North Sea, the Southern Ocean, the Indian Ocean, North America, South America, Africa, and New Zealand resulted in a comprehensive and detailed documentation of this group of calcareous nannofossils. Biostratigraphic ranges for each species are refined and a hypothetical evolutionary lineage for this genus is proposed. Two new species (Hornibrookina gracila and Hornibrookina indistincta), two new combinations (Hornibrookina elegans and Hornibrookina australis arca) and one new subspecies (Hornibrookina australis australis) are described. Morphometric analyses prove that Hornibrookina edwardsii and Hornibrookina teuriensis are distinctly different species with biostratigraphically useful ranges. Hornibrookina apellanizii is shown to be invalid.
{"title":"Evolution and taxonomy of the Paleogene calcareous nannofossil genus Hornibrookina","authors":"J. Self‐Trail, D. Watkins, J. Pospichal, E. L. Seefelt","doi":"10.47894/mpal.68.1.04","DOIUrl":"https://doi.org/10.47894/mpal.68.1.04","url":null,"abstract":"The genus Hornibrookina consists of enigmatic calcareous nannofossils that first appeared shortly after the K-Pg mass extinction. Due to their relative paucity in most published sections, specimens of this genus have not been previously studied in detail and their paleobiogeographic preferences and evolutionary history have been poorly understood. Biostratigraphic and morphometric analyses of Hornibrookina specimens from outcrops and cores from the Atlantic Ocean, the North Sea, the Southern Ocean, the Indian Ocean, North America, South America, Africa, and New Zealand resulted in a comprehensive and detailed documentation of this group of calcareous nannofossils. Biostratigraphic ranges for each species are refined and a hypothetical evolutionary lineage for this genus is proposed. Two new species (Hornibrookina gracila and Hornibrookina indistincta), two new combinations (Hornibrookina elegans and Hornibrookina australis arca) and one new subspecies (Hornibrookina australis australis) are described. Morphometric analyses prove that Hornibrookina edwardsii and Hornibrookina teuriensis are distinctly different species with biostratigraphically useful ranges. Hornibrookina apellanizii is shown to be invalid.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abyssocythere and Dutoitella are extant benthic bathyal ostracod genera that evolved during Coniacian to Santonian/Campanian time from shallow-water progenitors around southeastern Africa. Their Late Cretaceous development was primarily in the South Atlantic, but during the Palaeogene they spread to the Indian and Pacific oceans. The establishment of the psychrosphere (late Eocene-mid-Oligocene) flushed populations of each genus from their central Atlantic cradles into the Pacific, presumably through the Panama Seaway, so that contemporaneous centres of evolution developed disjunct clades: A. trinidadensis and D. praesuhmi. The psychrospheric oceanic event defined temporal thermophyllic and cryophyllic populations of the two genera. Three Neogene ocean events appear to have affected several regionally-confined species, inter alia one of which entailed a counterflow migration of A. atlantica from the eastern Pacific back into the central Atlantic during the mid-Miocene. Modern distributions of Abyssocythere and Dutoitella are disjunct: in the Atlantic both genera occur south of approximately 40 degrees N (Dutoitella), and equatorial areas (Abyssocythere); in the Indian Ocean both are confined to the southern part; and in the Pacific, Abyssocythere is restricted to central and north-eastern areas, and Dutoitella to the west and northwest. Neither genus evolved species that were more than para-cosmopolitan: A. diagrenona (South Atlantic-Indian; Eocene-Oligocene), A. trinidadensis complex (central Atlantic-NW Pacific; Oligocene-Miocene), D. crassinodosa complex (South Atlantic-Indian; Eocene), and D. praesuhmi (north and central Atlantic-central Pacific; Oligocene-Miocene).
{"title":"Review of the history of the deep-sea ostracod genera Abyssocythere Benson and Dutoitella Dingle, and their responses to Cretaceous - Cenozoic oceanic water-mass changes","authors":"R. Dingle","doi":"10.47894/mpal.68.3.04","DOIUrl":"https://doi.org/10.47894/mpal.68.3.04","url":null,"abstract":"Abyssocythere and Dutoitella are extant benthic bathyal ostracod genera that evolved during Coniacian to Santonian/Campanian time from shallow-water progenitors around southeastern Africa. Their Late Cretaceous development was primarily in the South Atlantic, but during the Palaeogene they spread to the Indian and Pacific oceans. The establishment of the psychrosphere (late Eocene-mid-Oligocene) flushed populations of each genus from their central Atlantic cradles into the Pacific, presumably through the Panama Seaway, so that contemporaneous centres of evolution developed disjunct clades: A. trinidadensis and D. praesuhmi. The psychrospheric oceanic event defined temporal thermophyllic and cryophyllic populations of the two genera. Three Neogene ocean events appear to have affected several regionally-confined species, inter alia one of which entailed a counterflow migration of A. atlantica from the eastern Pacific back into the central Atlantic during the mid-Miocene. Modern distributions of Abyssocythere and Dutoitella are disjunct: in the Atlantic both genera occur south of approximately 40 degrees N (Dutoitella), and equatorial areas (Abyssocythere); in the Indian Ocean both are confined to the southern part; and in the Pacific, Abyssocythere is restricted to central and north-eastern areas, and Dutoitella to the west and northwest. Neither genus evolved species that were more than para-cosmopolitan: A. diagrenona (South Atlantic-Indian; Eocene-Oligocene), A. trinidadensis complex (central Atlantic-NW Pacific; Oligocene-Miocene), D. crassinodosa complex (South Atlantic-Indian; Eocene), and D. praesuhmi (north and central Atlantic-central Pacific; Oligocene-Miocene).","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is a growing number of new foraminifera with agglutinated wall types held together by secreted crystallites of high-magnesium calcite that do not fit within the traditional definition of the Miliolida. In this study, we analyzed entire and sectioned foraminiferal specimens frommodern marine sediments collected off the Croatian coast (Adriatic Sea) using an Environmental Scanning Electron Microscope (ESEM) equipped with Energy-Dispersive x-ray-Spectroscopy (EDS). The investigated specimens resemble the miliolid genera Nubeculina Cushman 1924 and Falsonubeculina Amao and Kaminski 2019, but display characteristics of testmorphology and an agglutinated-porcelaneous wall structure that have not been previously observed in similar miliolids. Their wall structure is more like that observed in primitive agglutinated foraminifera such as Lagenammina rather than in true miliolids. New taxonomical inferences regarding the nubeculinid group of genera are discussed.
{"title":"The test wall of ?Nubeculina Cushman 1924 (Miliolida): updates on its agglutinated-porcelaneous wall structure from entire and sectioned specimens","authors":"L. Capotondi, M. Kaminski, N. Mancin","doi":"10.47894/mpal.68.6.02","DOIUrl":"https://doi.org/10.47894/mpal.68.6.02","url":null,"abstract":"There is a growing number of new foraminifera with agglutinated wall types held together by secreted crystallites of high-magnesium calcite that do not fit within the traditional definition of the Miliolida. In this study, we analyzed entire and sectioned foraminiferal specimens frommodern marine sediments collected off the Croatian coast (Adriatic Sea) using an Environmental Scanning Electron Microscope (ESEM) equipped with Energy-Dispersive x-ray-Spectroscopy (EDS). The investigated specimens resemble the miliolid genera Nubeculina Cushman 1924 and Falsonubeculina Amao and Kaminski 2019, but display characteristics of testmorphology and an agglutinated-porcelaneous wall structure that have not been previously observed in similar miliolids. Their wall structure is more like that observed in primitive agglutinated foraminifera such as Lagenammina rather than in true miliolids. New taxonomical inferences regarding the nubeculinid group of genera are discussed.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70446826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The technique proposed herein reveals the internal morphology of calcareous and agglutinated foraminifers in transmitted light, aiding in taxonomic identifications. It involves eliminating air bubbles inside tests through the application of a vacuum or high heat during oil immersion, and the subsequent mounting of the oil-clarified tests in compatible QSMM thermoplastics. The technique is rapid, nondestructive, allows internal viewing of large tests and is especially useful for small tests that are difficult to thin section. The technique has been used for mounting other microfossils, such as polycystine radiolarians.
{"title":"A new technique for observing the internal morphology of foraminiferal tests in transmitted light","authors":"Christopher M. McCauley, G. Nestell, M. Nestell","doi":"10.47894/mpal.68.6.04","DOIUrl":"https://doi.org/10.47894/mpal.68.6.04","url":null,"abstract":"The technique proposed herein reveals the internal morphology of calcareous and agglutinated foraminifers in transmitted light, aiding in taxonomic identifications. It involves eliminating air bubbles inside tests through the application of a vacuum or high heat during oil immersion, and the subsequent mounting of the oil-clarified tests in compatible QSMM thermoplastics. The technique is rapid, nondestructive, allows internal viewing of large tests and is especially useful for small tests that are difficult to thin section. The technique has been used for mounting other microfossils, such as polycystine radiolarians.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70447098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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