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Palaeoecological aspects and evolution of the Late Cretaceous oyster assemblages
Rantuch, Jakub ; Košťák, Martin (advisor) ; Mergl, Michal (referee) ; Reháková, Daniela (referee)
The presented thesis explores the palaeoecological aspects of the evolution of the well-known fossil oyster genus Rhynchostreon Bayle, 1874, a significant representative of Cretaceous fauna. The study integrates sedimentological (quartz grain size), geochemical (concentration of major oxides) and palaeobiological (taphonomy) proxies to categorise five oyster-bearing localities in the Bohemian Massif and the Pieniny Klippen Belt (Western Carpathians) into three environments with differing substrate characteristics, environmental energy levels and salinity regimes. Subsequently, the five specific palaeopopulations of Rhynchostreon suborbiculatum (Lamarck, 1801), occupying these habitats (including the dynamic Cenomanian nearshore, the quiet environment of the Turonian hemipelagic sea and the Cenomanian-Turonian marginal marine system influenced by variable fluvial activity), underwent a series of morphological and population studies. These studies involved the analyses of size-frequency distributions, morphotype structure, and shell thickness. Results from this multidisciplinary approach suggest that the salinity tolerance of R. suborbiculatum may be higher than commonly assumed, and its ecological response to climatic changes (i.e. the fluctuation of salinity, level of eutrophism, etc.) aligns with...
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Frequency of shell anomalies in Ordovician gastropods from Šárka Formation, Prague Basin
Šoobová, Adéla ; Frýda, Jiří (advisor) ; Mergl, Michal (referee)
The master thesis focuses on the frequency of anomalous structures on Ordovician gastropod shells coming from the Šárka Formation (Prague Basin) and deposited in the collections of the National Museum. The thesis summarized basic knowledge about teratological damage in different groups of gastropods, location and shape of damage and their possible causes. On the basis of extensive data collection on the occurrence of anomalous structures on gastropod shells (more than 4000 gastropod shells were analysed), differences in the frequency of teratological damage between different gastropod species (genera), their ontogenetic stages and different shell morphologies are quantitatively tested. Analyzes were performed by Fisher's exact test using the Holm-Bonferroni correction. The results of the thesis revealed an extremely low frequency of teratological damage in the Mid-Ordovician gastropods, a statistically significant difference in the frequency of damage between different gastropod species (genera), as well as between different shell morphologies and their ontogenetic stages. New results also confirm the increasing frequency of predation marks on gastropod shells during the Phanerozoic. Key words: gastropods, molluscs, shell, anomaly, damage, predation, frequency, Šárka Formation, Prague Basin
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Taxonomy, ecology and palaeogeographical significance of the genus Euorthisima (Brachiopoda) in the Prague Basin
Bartošová, Kateřina ; Mergl, Michal (advisor) ; Sklenář, Jan (referee)
Taxonomic position of the brachiopod genus Euorthisina HAVLÍ EK 1950 from the Ordovician of the Prague Basin (Czech republic) was subjected to wide discussions and disputes in the past. The genus was first classified within the superfamily Syntrophiiacea (order Pentamerida). Later, a separate family Euorthisinidae by Havlí ek (1977) was defined. At present, the family is assigned to the order Orthida and includes genera Euorthisina HAVLÍ EK, 1950, Lesserorthis BENEDETTO, 2007, Notorthisina HAVLÍ EK & BRANISA, 1980 and Protorthisina BENEDETTO, 2007. In this thesis, a revision of genus Euorthisina HAVLÍ EK 1950 with emphasis on taxonomic classification, palaeoecology and palaeogeographic occurrence of species E. moesta and E. minor described from the Ordovician of the Prague Basin has been made. Klí ová slova: Euorthisina, brachiopoda, Ordovician, Prague Basin, Czech republic.
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Semiquantitative study of the fossil association of the Dobrotivá Formation (Ordovician, Prague Basin) in Ejpovice
Luptáková, Monika ; Kraft, Petr (advisor) ; Mergl, Michal (referee)
The master thesis is focused on the semiquantitative study of the fossil association of the stratigraphically lowest layer No. 3 from the channel sample from the Ejpovice locality, where in the southern bank of the flooded quarry, the Dobrotivá Formation of the Ordovician of the Prague Basin is exposed in the thickness of several meters. The thesis briefly summarizes basic knowledge about the fossil associations of the Dobrotivá Formation, its lithology, stratigraphy and previous paleontological research at studied locality. Paleoecology of the fauna recorded in studied material is described. The main part of the thesis is focused on the taphonomy and associations of the fossils recorded in studied material. In the final part of the thesis, the overall fossil association is characterized depending on the paleoecology and taphonomy of preserved fossils, and the model of the paleoenvironment at the Ejpovice locality is discussed. Based on the lithology and studied fossil associations, it is assumed that a dysoxic environment with episodic currents prevailed in the Ejpovice locality. The fauna is species-depleted and taxa typical of the Dobrotivá Formation are rare. The fauna is mainly allochtonous and most of the organisms are considered as postmortal accumulations in this study. Key words:...
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In the footsteps of the "Šárka Balls" in Prague: a groundwork for a virtual educational trail
Hánová, Renata ; Kraft, Petr (advisor) ; Mergl, Michal (referee)
A meaningful popularisation should be based on scientific information. This dissertation establishes a groundwork for a future virtual educational trail in the territory of Prague, which would popularise geology and paleontology. The object of such popularisation are siliceous nodules from the Šárka Formation (Ordovician, Darriwilian), which are also known as "Šárka Balls". The issue is discussed using paleogeographical, geological and historical overviews. It describes the nodules, summarises the possibilities of their origin, and describes the fauna found within. A virtual educational trail has been chosen as the means to a successful popularisation due to the high building density in the area, which would make a standard educational trail unfeasible. This study also suggests possible stops on the trail.
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Pendent didymograptids of the Šárka Formation (lower Darriwilian) from the Ordovician of the Prague Basin
Strossová, Zuzana ; Kraft, Petr (advisor) ; Mergl, Michal (referee)
Historically, pendent didymograptids of the Šárka Formation belong to less researched group of Palaeozoic graptolites within the Prague Basin. The first occurrence of pendent didymograptids marks the basis of the Oretanian regional stratigraphical stage. Species diversity of pendent didymograptids significantly changed depending on the methodology used. When using the latest methodological approaches in their revision, new significant observations regarding these organisms can be determined. The quality of preservation of particular samples differs considerably; therefore, the application of biometric data in further analyses is limited. After almost 23 years, this thesis represents the first revision of the type material. The systematic part of this diploma thesis focuses on a thorough revision of pendent didymograptids found in shales and siliceous nodules. By applying modern scientific approaches, the lower species diversity of these organisms was determined in comparison to previous studies. The following species are regarded as valid by this thesis: Didymograptus vaccilanoides, Didymograptus artus, Didymograptus cf. bifidus, Didymograptus pseudogeminus and Didymograptus clavulus. Key words: Didymograptus, systematics, Ordovician, Šárka Formation, stratigraphy
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The Revision of selected Lower Carboniferous Arthropods from the Moravian Karst
Rak, Štěpán ; Burdíková, Zuzana (advisor) ; Mergl, Michal (referee) ; Hyžný, Matúš (referee)
In my dissertation thesis I made a revision of two selected groups of Lower Carboniferous arthropds from the Moravian Karst: trilobites and thylacocephalans. I studied their systematics, autecology as well as taxonomy. In the first part I mapped an occurrence of an atheloptic trilobite association in the Březina village vicinity. Based on a study the new trilobite association is erected. The second part is focused on the very first discovery of Lower Carboniferous thylacocephalan outside of US. Its specific carapace structure is studied. New species Paraconcavicaris viktoryni (Broda et al. 2020) is determined and compared to known species.
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Anomalous development of shells in the Paleozoic gastropods from the Prague Basin
Šoobová, Adéla ; Frýda, Jiří (advisor) ; Mergl, Michal (referee)
The thesis focused anomalous development of gastropod shells from the Prague Basin. Geology of the Prague Basin is briefly discissed in the first part of the thesis. and morpholigic structure of shell. Discussion of shell morphology in gastropods and different types of shell anomalies forms a main part of the thesis. Morphology of the gastropod shell seem to be very useful paleoecologycal indicator because the shells srecord their lives during whole ontogeny. Result of the thesis is a complete list of gastropod species in which the anomalous development of shells was found.
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Fossil associations of the Dobrotivá Formation
Luptáková, Monika ; Kraft, Petr (advisor) ; Mergl, Michal (referee)
The bachelor thesis is focused on the overview about a fundamental knowledge on the fossil associations of the Dobrotivá Formation. This unit represents a distinct level of the Prague Basin volcano-sedimentary infill formed during the boundary interval of the Middle and Upper Ordovician. Its main part is composed of the acquired and published data in the wider context of the neighboring paleocontinents and areas of peri-Gondwana. The thesis briefly describes the development of the Prague Basin and its paleogeography. It summarizes the lithology of the Dobrotivá Formation, its stratigraphic classification and the recently published knowledge on faunal associations in the Dobrotivá Formation, including their paleobiogeography and paleoecology. The bachelor thesis is considered to be a basis for further study of the Dobrotivá Formation. Key words: Ordovician, Prague Basin, assemblages, localities, stratigraphy, paleobiogeography
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Eocrinoid echinoderms from mid-Cambrian of the Barrandian area
Nohejlová, Martina ; Fatka, Oldřich (advisor) ; Mergl, Michal (referee) ; Valent, Martin (referee)
This thesis deals with the topic of eocrinoid echinoderms from the Barrandian area (Příbram- Jince Basin, mid-Cambrian, Drumian). The thesis is presented as a compilation of five published papers and an introduction. The introduction is an overview of current knowledge about eocrinoid echinoderms. It also includes links to new information from the five included papers, and serves as a unifying element for these professional publications. The topic of the thesis is focused on a revision of selected specimens of eocrinoid echinoderms, and the study of their ontogeny, phylogeny, palaeoecology and systematic position. This thesis has also improved our understanding of early evolution of basal blastozoans. This is the first study of Cambrian ontogenetic development on eocrinoid material from the Czech Republic. Complete ontogeny was described on the genus Akadocrinus, and it was possible to establish two basic phases in the development of this genus: pre-epispire-bearing phase and epispire-bearing phase. The new primitive blastozoan Felbabkacystis is described from the Jince Formation - its unique body plan highlights evolution of the body wall among blastozoans. Palaeoecology and phylogeny of the genus Vyscystis was studied, and phylogenetic analysis suggests a basal position of lepidocystoids among...
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