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Ladislav Slavik - One of the best experts on this subject based on the ideXlab platform.
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early devonian Lochkovian early emsian bioevents and conodont response in the prague synform czech republic
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Ladislav Slavik, Jindřich HladilAbstract:Abstract The Devonian succession of the Prague Synform is characterized by two major lithofacies: shallow-water biodetrital, mostly crinoidal limestones that also include a reefal skeletal accumulation of Pragian age, and a more pelagic facies that is represented mostly by calcisiltites. Among the several Devonian prominent sea-level fluctuations, some can be traced globally, e.g., the Basal Pragian and Kacak events. In recent years, conodont biostratigraphy of the Early Devonian (Lochkovian, Pragian and early Emsian) of the Prague Synform has been refined. The regional subdivision of the Lower Devonian in its type area has been greatly improved by the integration of new biostratigraphic, chemostratigraphic, sedimentological, and petrophysical data that has, in turn, strengthened global correlations for this interval in Earth's history. The complete conodont biozonation of the Early Devonian interval (basal Lochkovian – earliest Emsian) in the Prague Synform includes 17 biozones, which can be applied to sections representing various depositional environments and have more global applicability than previously proposed ‘global’ conodont biozonations. The zonal scale enables a precise biostratigraphic delimitation of the major Early Devonian biotic events (Silurian-Devonian Boundary Event, Lochkovian-Pragian Event and Basal Zlichovian Event). There were major changes in the conodont fauna in response to the Silurian-Devonian Boundary and Lochkovian-Pragian events, however the Basal Zlichovian Event was only characterized by a very gradual transition in the conodont fauna. In parallel to the traditional events defined for the Prague Synform, seven other significant conodont events have been documented. These events represent major turnovers in the conodont fauna that have a direct impact on conodont biostratigraphy, specifically at a global scale. The Icriodus and Irregularis events are congruent with the lower boundaries of the Lochkovian and Pragian stages, respectively. The conodont events established in the Prague Synform largely reflect variations in the seawater depth but are generally independent of lithological changes within sections of the Prague Synform.
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Early Devonian (Lochkovian – early Emsian) bioevents and conodont response in the Prague Synform (Czech Republic)
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Ladislav Slavik, Jindřich HladilAbstract:Abstract The Devonian succession of the Prague Synform is characterized by two major lithofacies: shallow-water biodetrital, mostly crinoidal limestones that also include a reefal skeletal accumulation of Pragian age, and a more pelagic facies that is represented mostly by calcisiltites. Among the several Devonian prominent sea-level fluctuations, some can be traced globally, e.g., the Basal Pragian and Kacak events. In recent years, conodont biostratigraphy of the Early Devonian (Lochkovian, Pragian and early Emsian) of the Prague Synform has been refined. The regional subdivision of the Lower Devonian in its type area has been greatly improved by the integration of new biostratigraphic, chemostratigraphic, sedimentological, and petrophysical data that has, in turn, strengthened global correlations for this interval in Earth's history. The complete conodont biozonation of the Early Devonian interval (basal Lochkovian – earliest Emsian) in the Prague Synform includes 17 biozones, which can be applied to sections representing various depositional environments and have more global applicability than previously proposed ‘global’ conodont biozonations. The zonal scale enables a precise biostratigraphic delimitation of the major Early Devonian biotic events (Silurian-Devonian Boundary Event, Lochkovian-Pragian Event and Basal Zlichovian Event). There were major changes in the conodont fauna in response to the Silurian-Devonian Boundary and Lochkovian-Pragian events, however the Basal Zlichovian Event was only characterized by a very gradual transition in the conodont fauna. In parallel to the traditional events defined for the Prague Synform, seven other significant conodont events have been documented. These events represent major turnovers in the conodont fauna that have a direct impact on conodont biostratigraphy, specifically at a global scale. The Icriodus and Irregularis events are congruent with the lower boundaries of the Lochkovian and Pragian stages, respectively. The conodont events established in the Prague Synform largely reflect variations in the seawater depth but are generally independent of lithological changes within sections of the Prague Synform.
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Oxygen and carbon stable isotope records of the Lochkovian-Pragian boundary interval from the Prague Basin (Lower Devonian, Czech Republic)
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Hedvika Weinerová, Ondřej Bábek, Ladislav Slavik, Hubert B. Vonhof, Michael M. Joachimski, Jindřich HladilAbstract:Abstract Climate changes close to the Lochkovian-Pragian Event are still widely discussed. Carbonate δ18O and δ13C and conodont apatite δ18O from medial to distal carbonate ramp sediments were analysed to provide further stable isotope data from the stratotype area in the Prague Basin. The uppermost Silurian to lower Emsian δ18O trends are put into an updated conodont biostratigraphy framework. Carbonate δ18O and δ13C are discussed in the context of facies-dependent diagenesis. The δ13C pattern measured from different sections enables the correlation of intervals with development of different facies inside the Prague Basin. Positive δ13C shifts are often coupled with trends of decreasing computed gamma-ray (CGR) values interpreted as regressions, whereas negative δ13C shifts commonly coincide with opposite trends in CGR. The Lochkovian-Pragian boundary interval coincided with an increase in carbonate δ13C and an increase in the δ18O of conodont apatite and carbonate, which we interpret as consequence of climate cooling. Generally, the Lochkovian was warmer than the Pragian and earliest Emsian.
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Refining the late Silurian sea-level history of the Prague Syncline—a case study based on the Přídolí GSSP (Czech Republic)
Facies, 2018Co-Authors: František Vacek, Ladislav Slavik, Katarzyna Sobień, Pavel ČápAbstract:A 50-m-thick section in the Požáry quarry, Prague Syncline (Czech Republic) spanning the upper Silurian (uppermost Ludlow and Přídolí) to the lowermost Devonian (Lochkovian) has been studied using sedimentological and physical stratigraphical (gamma-ray spectrometry) methods combined with conodont biostratigraphy. Conodont data demonstrate the presence of local conodont biozones: “ Ozarkodina” crispa (uppermost Ludlow)— Zieglerodina zellmeri (base of Přídolí)— Zieglerodina ivochlupaci — Delotaxis detorta —“ Ozarkodina” eosteinhornensis s.s.— Zieglerodina klonkensis — Icriodus hesperius - optima (lowermost Lochkovian). The studied section represents a transgressive–regressive facies succession characterized by a transition from distal calciturbidites deposited in a distally steepened carbonate platform during transgression and sea-level highstand ( crispa to lower ivochlupaci zones) to mixed calciturbidites/coarse-grained bioclastic limestones (falling-stage systems tract, upper ivochlupaci to lower klonkensis zones). The upper part of the succession consists of bioclastic limestones corresponding to a subtidal setting between storm-wave and fair-weather wave base (lowstand systems tract in upper klonkensis and hesperius - optima zones). This interpretation corresponds to the late Silurian global sea-level pattern as recorded in other regions. Thus the depositional system is interpreted as mostly driven by eustasy with short-lived periods of influence from local tectonics.
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refining the early devonian time scale using milankovitch cyclicity in Lochkovian pragian sediments prague synform czech republic
Earth and Planetary Science Letters, 2016Co-Authors: A. C. Silva, Leona Chadimova, Jindřich Hladil, Frederik J Hilgen, Ondřej Bábek, Ladislav Slavik, Mark J. DekkersAbstract:Abstract The Early Devonian geological time scale (base of the Devonian at 418.8 ± 2.9 Myr , Becker et al., 2012 ) suffers from poor age control, with associated large uncertainties between 2.5 and 4.2 Myr on the stage boundaries. Identifying orbital cycles from sedimentary successions can serve as a very powerful chronometer to test and, where appropriate, improve age models. Here, we focus on the Lochkovian and Pragian, the two lowermost Devonian stages. High-resolution magnetic susceptibility ( χ in – 5 to 10 cm sampling interval) and gamma ray spectrometry (GRS – 25 to 50 cm sampling interval) records were gathered from two main limestone sections, Požar-CS (118 m, spanning the Lochkov and Praha Formations) and Pod Barrandovem (174 m; Praha Formation), both in the Czech Republic. An additional section (Branžovy, 65 m, Praha Formation) was sampled for GRS (every 50 cm). The χ in and GRS records are very similar, so χ in variations are driven by variations in the samples' paramagnetic clay mineral content, reflecting changes in detrital input. Therefore, climatic variations are very likely captured in our records. Multiple spectral analysis and statistical techniques such as: Continuous Wavelet Transform, Evolutive Harmonic Analysis, Multi-taper method and Average Spectral Misfit, were used in concert to reach an optimal astronomical interpretation. The Požar-CS section shows distinctly varying sediment accumulation rates. The Lochkovian (essentially equivalent to the Lochkov Formation (Fm.)) is interpreted to include a total of nineteen 405 kyr eccentricity cycles, constraining its duration to 7.7 ± 2.8 Myr . The Praha Fm. includes fourteen 405 kyr eccentricity cycles in the three sampled sections, while the Pragian Stage only includes about four 405 kyr eccentricity cycles, thus exhibiting durations of 5.7 ± 0.6 Myr and 1.7 ± 0.7 Myr respectively. Because the Lochkov Fm. contains an interval with very low sediment accumulation rate and because the Praha Fm. was cross-validated in three different sections, the uncertainty in the duration of the Lochkov Fm. and the Lochkovian is larger than that of the Praha Fm. and Pragian. The new floating time scales for the Lochkovian and Pragian stages have an unprecedented precision, with reduction in the uncertainty by a factor of 1.7 for the Lochkovian and of ∼6 for the Pragian. Furthermore, longer orbital modulation cycles are also identified with periodicities of ∼1000 kyr and 2000–2500 kyr.
Jindřich Hladil - One of the best experts on this subject based on the ideXlab platform.
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early devonian Lochkovian early emsian bioevents and conodont response in the prague synform czech republic
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Ladislav Slavik, Jindřich HladilAbstract:Abstract The Devonian succession of the Prague Synform is characterized by two major lithofacies: shallow-water biodetrital, mostly crinoidal limestones that also include a reefal skeletal accumulation of Pragian age, and a more pelagic facies that is represented mostly by calcisiltites. Among the several Devonian prominent sea-level fluctuations, some can be traced globally, e.g., the Basal Pragian and Kacak events. In recent years, conodont biostratigraphy of the Early Devonian (Lochkovian, Pragian and early Emsian) of the Prague Synform has been refined. The regional subdivision of the Lower Devonian in its type area has been greatly improved by the integration of new biostratigraphic, chemostratigraphic, sedimentological, and petrophysical data that has, in turn, strengthened global correlations for this interval in Earth's history. The complete conodont biozonation of the Early Devonian interval (basal Lochkovian – earliest Emsian) in the Prague Synform includes 17 biozones, which can be applied to sections representing various depositional environments and have more global applicability than previously proposed ‘global’ conodont biozonations. The zonal scale enables a precise biostratigraphic delimitation of the major Early Devonian biotic events (Silurian-Devonian Boundary Event, Lochkovian-Pragian Event and Basal Zlichovian Event). There were major changes in the conodont fauna in response to the Silurian-Devonian Boundary and Lochkovian-Pragian events, however the Basal Zlichovian Event was only characterized by a very gradual transition in the conodont fauna. In parallel to the traditional events defined for the Prague Synform, seven other significant conodont events have been documented. These events represent major turnovers in the conodont fauna that have a direct impact on conodont biostratigraphy, specifically at a global scale. The Icriodus and Irregularis events are congruent with the lower boundaries of the Lochkovian and Pragian stages, respectively. The conodont events established in the Prague Synform largely reflect variations in the seawater depth but are generally independent of lithological changes within sections of the Prague Synform.
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Early Devonian (Lochkovian – early Emsian) bioevents and conodont response in the Prague Synform (Czech Republic)
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Ladislav Slavik, Jindřich HladilAbstract:Abstract The Devonian succession of the Prague Synform is characterized by two major lithofacies: shallow-water biodetrital, mostly crinoidal limestones that also include a reefal skeletal accumulation of Pragian age, and a more pelagic facies that is represented mostly by calcisiltites. Among the several Devonian prominent sea-level fluctuations, some can be traced globally, e.g., the Basal Pragian and Kacak events. In recent years, conodont biostratigraphy of the Early Devonian (Lochkovian, Pragian and early Emsian) of the Prague Synform has been refined. The regional subdivision of the Lower Devonian in its type area has been greatly improved by the integration of new biostratigraphic, chemostratigraphic, sedimentological, and petrophysical data that has, in turn, strengthened global correlations for this interval in Earth's history. The complete conodont biozonation of the Early Devonian interval (basal Lochkovian – earliest Emsian) in the Prague Synform includes 17 biozones, which can be applied to sections representing various depositional environments and have more global applicability than previously proposed ‘global’ conodont biozonations. The zonal scale enables a precise biostratigraphic delimitation of the major Early Devonian biotic events (Silurian-Devonian Boundary Event, Lochkovian-Pragian Event and Basal Zlichovian Event). There were major changes in the conodont fauna in response to the Silurian-Devonian Boundary and Lochkovian-Pragian events, however the Basal Zlichovian Event was only characterized by a very gradual transition in the conodont fauna. In parallel to the traditional events defined for the Prague Synform, seven other significant conodont events have been documented. These events represent major turnovers in the conodont fauna that have a direct impact on conodont biostratigraphy, specifically at a global scale. The Icriodus and Irregularis events are congruent with the lower boundaries of the Lochkovian and Pragian stages, respectively. The conodont events established in the Prague Synform largely reflect variations in the seawater depth but are generally independent of lithological changes within sections of the Prague Synform.
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Oxygen and carbon stable isotope records of the Lochkovian-Pragian boundary interval from the Prague Basin (Lower Devonian, Czech Republic)
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Hedvika Weinerová, Ondřej Bábek, Ladislav Slavik, Hubert B. Vonhof, Michael M. Joachimski, Jindřich HladilAbstract:Abstract Climate changes close to the Lochkovian-Pragian Event are still widely discussed. Carbonate δ18O and δ13C and conodont apatite δ18O from medial to distal carbonate ramp sediments were analysed to provide further stable isotope data from the stratotype area in the Prague Basin. The uppermost Silurian to lower Emsian δ18O trends are put into an updated conodont biostratigraphy framework. Carbonate δ18O and δ13C are discussed in the context of facies-dependent diagenesis. The δ13C pattern measured from different sections enables the correlation of intervals with development of different facies inside the Prague Basin. Positive δ13C shifts are often coupled with trends of decreasing computed gamma-ray (CGR) values interpreted as regressions, whereas negative δ13C shifts commonly coincide with opposite trends in CGR. The Lochkovian-Pragian boundary interval coincided with an increase in carbonate δ13C and an increase in the δ18O of conodont apatite and carbonate, which we interpret as consequence of climate cooling. Generally, the Lochkovian was warmer than the Pragian and earliest Emsian.
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refining the early devonian time scale using milankovitch cyclicity in Lochkovian pragian sediments prague synform czech republic
Earth and Planetary Science Letters, 2016Co-Authors: A. C. Silva, Leona Chadimova, Jindřich Hladil, Frederik J Hilgen, Ondřej Bábek, Ladislav Slavik, Mark J. DekkersAbstract:Abstract The Early Devonian geological time scale (base of the Devonian at 418.8 ± 2.9 Myr , Becker et al., 2012 ) suffers from poor age control, with associated large uncertainties between 2.5 and 4.2 Myr on the stage boundaries. Identifying orbital cycles from sedimentary successions can serve as a very powerful chronometer to test and, where appropriate, improve age models. Here, we focus on the Lochkovian and Pragian, the two lowermost Devonian stages. High-resolution magnetic susceptibility ( χ in – 5 to 10 cm sampling interval) and gamma ray spectrometry (GRS – 25 to 50 cm sampling interval) records were gathered from two main limestone sections, Požar-CS (118 m, spanning the Lochkov and Praha Formations) and Pod Barrandovem (174 m; Praha Formation), both in the Czech Republic. An additional section (Branžovy, 65 m, Praha Formation) was sampled for GRS (every 50 cm). The χ in and GRS records are very similar, so χ in variations are driven by variations in the samples' paramagnetic clay mineral content, reflecting changes in detrital input. Therefore, climatic variations are very likely captured in our records. Multiple spectral analysis and statistical techniques such as: Continuous Wavelet Transform, Evolutive Harmonic Analysis, Multi-taper method and Average Spectral Misfit, were used in concert to reach an optimal astronomical interpretation. The Požar-CS section shows distinctly varying sediment accumulation rates. The Lochkovian (essentially equivalent to the Lochkov Formation (Fm.)) is interpreted to include a total of nineteen 405 kyr eccentricity cycles, constraining its duration to 7.7 ± 2.8 Myr . The Praha Fm. includes fourteen 405 kyr eccentricity cycles in the three sampled sections, while the Pragian Stage only includes about four 405 kyr eccentricity cycles, thus exhibiting durations of 5.7 ± 0.6 Myr and 1.7 ± 0.7 Myr respectively. Because the Lochkov Fm. contains an interval with very low sediment accumulation rate and because the Praha Fm. was cross-validated in three different sections, the uncertainty in the duration of the Lochkov Fm. and the Lochkovian is larger than that of the Praha Fm. and Pragian. The new floating time scales for the Lochkovian and Pragian stages have an unprecedented precision, with reduction in the uncertainty by a factor of 1.7 for the Lochkovian and of ∼6 for the Pragian. Furthermore, longer orbital modulation cycles are also identified with periodicities of ∼1000 kyr and 2000–2500 kyr.
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Refining the Early Devonian time scale using Milankovitch cyclicity in Lochkovian–Pragian sediments (Prague Synform, Czech Republic)
Earth and Planetary Science Letters, 2016Co-Authors: A. C. Silva, Leona Chadimova, Jindřich Hladil, Frederik J Hilgen, Ondřej Bábek, Ladislav Slavik, Mark J. DekkersAbstract:Abstract The Early Devonian geological time scale (base of the Devonian at 418.8 ± 2.9 Myr , Becker et al., 2012 ) suffers from poor age control, with associated large uncertainties between 2.5 and 4.2 Myr on the stage boundaries. Identifying orbital cycles from sedimentary successions can serve as a very powerful chronometer to test and, where appropriate, improve age models. Here, we focus on the Lochkovian and Pragian, the two lowermost Devonian stages. High-resolution magnetic susceptibility ( χ in – 5 to 10 cm sampling interval) and gamma ray spectrometry (GRS – 25 to 50 cm sampling interval) records were gathered from two main limestone sections, Požar-CS (118 m, spanning the Lochkov and Praha Formations) and Pod Barrandovem (174 m; Praha Formation), both in the Czech Republic. An additional section (Branžovy, 65 m, Praha Formation) was sampled for GRS (every 50 cm). The χ in and GRS records are very similar, so χ in variations are driven by variations in the samples' paramagnetic clay mineral content, reflecting changes in detrital input. Therefore, climatic variations are very likely captured in our records. Multiple spectral analysis and statistical techniques such as: Continuous Wavelet Transform, Evolutive Harmonic Analysis, Multi-taper method and Average Spectral Misfit, were used in concert to reach an optimal astronomical interpretation. The Požar-CS section shows distinctly varying sediment accumulation rates. The Lochkovian (essentially equivalent to the Lochkov Formation (Fm.)) is interpreted to include a total of nineteen 405 kyr eccentricity cycles, constraining its duration to 7.7 ± 2.8 Myr . The Praha Fm. includes fourteen 405 kyr eccentricity cycles in the three sampled sections, while the Pragian Stage only includes about four 405 kyr eccentricity cycles, thus exhibiting durations of 5.7 ± 0.6 Myr and 1.7 ± 0.7 Myr respectively. Because the Lochkov Fm. contains an interval with very low sediment accumulation rate and because the Praha Fm. was cross-validated in three different sections, the uncertainty in the duration of the Lochkov Fm. and the Lochkovian is larger than that of the Praha Fm. and Pragian. The new floating time scales for the Lochkovian and Pragian stages have an unprecedented precision, with reduction in the uncertainty by a factor of 1.7 for the Lochkovian and of ∼6 for the Pragian. Furthermore, longer orbital modulation cycles are also identified with periodicities of ∼1000 kyr and 2000–2500 kyr.
Jinzhuang Xue - One of the best experts on this subject based on the ideXlab platform.
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A horseshoe crab (Arthropoda: Chelicerata: Xiphosura) from the Lower Devonian (Lochkovian) of Yunnan, China
Geological Magazine, 2012Co-Authors: James C. Lamsdell, Jinzhuang Xue, Paul A. SeldenAbstract:A single specimen of a new species of the synziphosurine Kasibelinurus Pickett, 1993 is described from the Lower Devonian (Lochkovian) Xiaxishancun Formation of Yunnan Province, China. The new species, K. yueya sp. nov., extends the geographic extent of the family Kasibelinuridae from the Australian palaeocontinent to the South China palaeocontinent, and the stratigraphic range back some 50 Ma from Late to Early Devonian.
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Lochkovian plants from the Xitun Formation of Yunnan, China, and their palaeophytogeographical significance
Geological Magazine, 2011Co-Authors: Jinzhuang XueAbstract:A megafossil plant assemblage containing three zosterophyll plants (Gen. nov. A, aff. Huia sp. and a unnamed spike) is described from the Lower Devonian Xitun Formation (Lochkovian) of Qujing, Yunnan Province, China, providing new data on the diversity of plant types during the Lochkovian, a time poorly represented by fossil vascular plants. Gen. nov. A has a character combination of naked axes, a diagnostic branching pattern (i.e. K-type branching as well as small lateral branches scattered along the axes) and lateral stalked sporangia. Aff. Huia sp. has ovate and stalked sporangia which are arranged in loose spirals and are reflexed adaxially. Combining the plants previously reported from the Xitun Formation (i.e. Xitunia spinitheca , Zosterophyllum shengfengense and Z . minorstachyum ), the Xitun flora is dominated by zosterophylls and exhibits varied vegetative and fertile morphologies. Unlike the coeval plant assemblages in many localities of Laurussia and western Gondwana, which are mainly composed of plants with isotomous branching and terminal sporangia, the Lochkovian flora of South China is dominated by zosterophylls, documenting the existence of a distinct Northwest Gondwanan phytogeographic unit in the Lochkovian and a strong effect of phytogeographical isolation.
Valentina Karatajūtė-talimaa - One of the best experts on this subject based on the ideXlab platform.
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NEW CORVASPIDS FROM THE Lochkovian (LOWER DEVONIAN) OF SEVERNAYA ZEMLYA, RUSSIA (VERTEBRATA: PTERASPIDOMORPHI: HETEROSTRACI)
Journal of Vertebrate Paleontology, 2001Co-Authors: Alain Blieck, Valentina Karatajūtė-talimaaAbstract:Abstract The new genus and species Corveolepis elgae is described from the Lochkovian, Severnaya Zemlya formation of October Revolution Island, Severnaya Zemlya. It is ascribed to the family Corvaspididae whose diagnosis is corrected. Corvaspis arctica Loeffler and Dineley is designated as the type species of Corveolepis. Previously described taxa such as “Corvaspis kingi” auct. and Corvaspis graticulata Dineley from Spitsbergen are included with doubt in Corveolepis. Other new material includes Corveolepis? sp. cf. C.? graticulata from the Lochkovian, Pod'emnaya formation of October Revolution Island. This material is used as supporting evidence for a correlation of Lower Devonian vertebrate-bearing strata between Severnaya Zemlya and Spitsbergen.
Alain Blieck - One of the best experts on this subject based on the ideXlab platform.
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A new species of cyathaspid (Vertebrata: Pteraspidomorphi: Heterostraci) from the Lower Devonian Drake Bay Formation, Prince of Wales Island, Nunavut, Arctic Canada
Estonian Academy Publishers, 2018Co-Authors: David K. Elliott, Linda S. Lassiter, Alain BlieckAbstract:A new genus and species of cyathaspid heterostracan, Faberaspis elgae, is described from the Early Devonian (Lochkovian, Pedavis pesavis conodont Zone) Drake Bay Formation of Prince of Wales Island, Nunavut, Arctic Canada, where it is associated with a rich shallow marine invertebrate fauna. Faberaspis is most closely related to Poraspis, but differs in details of the ornament and in possessing a more complete network of lateral line canals
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Early Devonian fishes from coastal De Long Strait, central Chukotka, Arctic Russia
Geodiversitas, 2013Co-Authors: Elga Mark-kurik, Alain Blieck, Carole J. Burrow, Susan TurnerAbstract:ABSTRACT Calcareous and sandy deposits from the basal members of the Enmakaj and Pil'hikaj formations in coastal exposures along the De Long Strait in central Chukotka, Arctic far-eastern Russia, have yielded two assemblages of fossil fish comprising heterostracan plate fragments, turiniid and other thelodont scales, acanthodian scales and a partial tooth, typical of the Old Red Sandstone facies. Exceptional are acanthothoracid placoderm platelets characteristic of marine facies. In addition a sarcopterygian fragment have been found in Member 1 of the Enmakaj Formation. Some scale surfaces show an unusual, scoured preservation. A Lochkovian age, and most probably basal Lochkovian, is supported for the Enmakaj assemblage, and a somewhat later Lochkovian age is supposed for the Pil'hikaj assemblage. The palaeobiogeographic affinities of these assemblages based on the heterostracans and thelodonts are with other Lochkovian occurrences in Arctic regions such as Severnaya Zemlya, Spitsbergen and the northern a...
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Vertebrate macroremains as stratigraphic markers : the case of the Lower Devonian “Kujdanowiaspis assemblage” from Podolia (Ukraine) and Celtiberia (Spain)
2011Co-Authors: Vincent Dupret, Peter Carls, Carlos Martínez-pérez, Hector Botella, Alain BlieckAbstract:The vertebrate fauna, including chondrichthyan microremains and osteostracan and placoderm macroremains encountered in the Lower Devonian (i.e. Lochkovian and Pragian) deposits from Podolia (Ukraine; see list in Voichyshyn, 2001) was considered as unique. Unfortunately, because of the Old Red Sandstone facies, the stratigraphic boundaries were very difficult to determine. Until recently, most of the units were lithologic. The occurrence of the arthrodire placoderm Kujdanowiaspis buczacziensis has since been proposed to mark the beginning of the Pragian, owing to a number of correlations between fossil distributions (i.e. the pteraspidiform Althaspis) in Western Europe and Podolia (Dupret and Blieck, 2009).Recently, the long time “unique” placoderm and chondrichthyan faunal assemblage from Podolia has been found in Spain (Martinez-Perez et al., in press; Dupret et al., submitted). The absence of K. buczacziensis, nevertheless, leads us to consider an age older than Pragian, i.e. late Lochkovian. This dating confirms previous works mainly based on invertebrates and conodonts. These “double check” processes confirm the possibility of using macrovertebrate remains for stratigraphic purposes.The occurence of the same fauna during the Late Lochkovian in Podolia (southern margin of Laurussia) and in Spain (Armorican ”block”, part of northern margin of Gondwana or independant component), leads us to favour palaeogeographic reconstructions showing a proximity between both palaeo-provinces, allowing for the formation of, at least, punctual migratory paths. Moreover, the Old Red Sandstones have long been considered as non-marine deposits, especially in Podolia, despite the discovery of seldom brachiopod (lingulid) fragments. The similar faunal composition between Podolia and Celtiberia (the latter being clearly marine) challenges the non-marine status of the Podolian deposits.
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NEW CORVASPIDS FROM THE Lochkovian (LOWER DEVONIAN) OF SEVERNAYA ZEMLYA, RUSSIA (VERTEBRATA: PTERASPIDOMORPHI: HETEROSTRACI)
Journal of Vertebrate Paleontology, 2001Co-Authors: Alain Blieck, Valentina Karatajūtė-talimaaAbstract:Abstract The new genus and species Corveolepis elgae is described from the Lochkovian, Severnaya Zemlya formation of October Revolution Island, Severnaya Zemlya. It is ascribed to the family Corvaspididae whose diagnosis is corrected. Corvaspis arctica Loeffler and Dineley is designated as the type species of Corveolepis. Previously described taxa such as “Corvaspis kingi” auct. and Corvaspis graticulata Dineley from Spitsbergen are included with doubt in Corveolepis. Other new material includes Corveolepis? sp. cf. C.? graticulata from the Lochkovian, Pod'emnaya formation of October Revolution Island. This material is used as supporting evidence for a correlation of Lower Devonian vertebrate-bearing strata between Severnaya Zemlya and Spitsbergen.
