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Latest Ludlow chitinozoans from the Prague Basin: significanec for correlations and succession during Kozlowskii/Lau extinction events
Vodička, Jakub ; Fatka, Oldřich (advisor) ; Štorch, Petr (referee)
Two sections, Všeradice and Kosov, represent continuous sedimentary succession situated in the Prague Basin. No detailed research on stratigraphical level equal the N. kozlowskii graptolite zone focusing on chitinozoans, has not yet been conducted in the Prague Basin and is also very scarce globally. Limestone beds, examined for chitinozoans, were not very productive. Chitinozoan reaction on extinction is visible, if we compile data from both sections. The pre-extinct chitinozoan fauna is characterized by the Conochitinidae family. Samples from the post-extinct interval contained no chitinozoas. The interval of fauna recovery is characterized mainly by the Eisenackitina genera. In this interval, global zone for the uppermost Ludfordian, represented by E. barrandei, can be confirmed. In agreement with all the published literature, we have not found E. philipi, index taxa of the former global zone in the Prague Basin. E. lagenomorpha appears stratigraphically only slightly below E. barrandei and therefore it cannot substitute E. philipi, as it is used in Baltika region. chitinozoa, Prague Basin, Kozlowskii, Lau, extinction, Ludfordian, stratigraphy
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Late Silurian and Early Devonian Environmental and Biotic Changes
Manda, Štěpán ; Frýda, Jiří (advisor) ; Vašíček, Zdeněk (referee) ; Štorch, Petr (referee)
The mid-Ludfordian crisis (Kozlowskiii/Lau Event) was studied in detail. The extinction coincided with short-term shallowing, which reflected short glacial periode, as well as with incipient increase of organic carbon δ13 C in sediments. As suggested by many authors, this crisis affected especially graptolites and conodonts, but new data illustrate that all benthic groups were affected by the extinction. In addition, the structure of communities distinctly changed during the event. Recovery of ecosystems was accompanied by large-scale immigration of new fauna, contemporaneously with shallowing. The post-extinction interval took place during high stand and anoxic period. Extinction intervals coincide with sequence boundaries associated with gaps in sedimentation. So far poorly studied cephalopods were chosen as a model group for examination of trends in macroevolution and global change of ecosystems during the Silurian and Devonian. New established cephalopod groups that differ in embryonic strategy and mode of life of early hatched specimens and adults were used in study of biodiversity and selectivity of extinctions. The early ontogenetic strategies and size of eggs (incubation time) of the cephalopods significantly influenced survival and diversity during extinction intervals. It was documented...
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Latest Ludlow chitinozoans from the Prague Basin: significanec for correlations and succession during Kozlowskii/Lau extinction events
Vodička, Jakub ; Fatka, Oldřich (advisor) ; Štorch, Petr (referee)
Two sections, Všeradice and Kosov, represent continuous sedimentary succession situated in the Prague Basin. No detailed research on stratigraphical level equal the N. kozlowskii graptolite zone focusing on chitinozoans, has not yet been conducted in the Prague Basin and is also very scarce globally. Limestone beds, examined for chitinozoans, were not very productive. Chitinozoan reaction on extinction is visible, if we compile data from both sections. The pre-extinct chitinozoan fauna is characterized by the Conochitinidae family. Samples from the post-extinct interval contained no chitinozoas. The interval of fauna recovery is characterized mainly by the Eisenackitina genera. In this interval, global zone for the uppermost Ludfordian, represented by E. barrandei, can be confirmed. In agreement with all the published literature, we have not found E. philipi, index taxa of the former global zone in the Prague Basin. E. lagenomorpha appears stratigraphically only slightly below E. barrandei and therefore it cannot substitute E. philipi, as it is used in Baltika region. chitinozoa, Prague Basin, Kozlowskii, Lau, extinction, Ludfordian, stratigraphy
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Late Silurian and Early Devonian Environmental and Biotic Changes
Manda, Štěpán ; Frýda, Jiří (advisor) ; Vašíček, Zdeněk (referee) ; Štorch, Petr (referee)
The mid-Ludfordian crisis (Kozlowskiii/Lau Event) was studied in detail. The extinction coincided with short-term shallowing, which reflected short glacial periode, as well as with incipient increase of organic carbon δ13 C in sediments. As suggested by many authors, this crisis affected especially graptolites and conodonts, but new data illustrate that all benthic groups were affected by the extinction. In addition, the structure of communities distinctly changed during the event. Recovery of ecosystems was accompanied by large-scale immigration of new fauna, contemporaneously with shallowing. The post-extinction interval took place during high stand and anoxic period. Extinction intervals coincide with sequence boundaries associated with gaps in sedimentation. So far poorly studied cephalopods were chosen as a model group for examination of trends in macroevolution and global change of ecosystems during the Silurian and Devonian. New established cephalopod groups that differ in embryonic strategy and mode of life of early hatched specimens and adults were used in study of biodiversity and selectivity of extinctions. The early ontogenetic strategies and size of eggs (incubation time) of the cephalopods significantly influenced survival and diversity during extinction intervals. It was documented...
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