National Repository of Grey Literature 7 records found  Search took 0.00 seconds. 
Paleozoic glaciation as an analog for Quaternary glacial cycles?
Kubíček, Martin ; Laurin, Jiří (advisor) ; Laibl, Lukáš (referee)
This bachelor thesis is focused on the comparison of the two main glacial periods of the Phanerozoic, the Late Paleozoic Ice Age and the Cenozoic Ice Age including Pleistocene. The main goal of the thesis is to compare the factors of glaciation and their controlling mechanisms on short and long-term scales, and the basic features of the Earth's circulation. Last but not least, the evaluation of unresolved questions and consideration of the possibility of using data from the Cenozoic, which point to a very complex behaviour of the climate system components. In both periods compared, the main climate driver appears to be the atmospheric greenhouse gas content. Another common feature is the declining trend in temperature, manifested initially by a less significant and ephemeral glaciation during the Upper Devonian, Eocene and Oligocene. The transition to the coldest phases with the lowest average temperature and the largest ice volume is characteristic. Based on CO2 content, amplitude of glacioeustatic oscillations or Milankovitch cycles, a sequence of several glaciation events in the Serpukhovian to Sakmarian interval can be considered as an analogue of the Pleistocene. The difference from the Pleistocene glaciation is presence of a large number of glaciation centres in the Gondwana area. Some...
Ontogeny of trilobites
Laibl, Lukáš ; Fatka, Oldřich (advisor) ; Budil, Petr (referee)
The thesis summarizes the current state of knowledge about the ontogeny of trilobites. The introductory chapters describe the basic morphology and anatomy of trilobites, and also mention their ecology, occurrence and feeding habits. In the main part of my thesis, I first summarized the existing research in this area, and also dealt in detail with methods of preservation of trilobite larvae, their reproduction, growth, embryology, postembryonal development, segmentation and ecology. I also mentioned the possible usage of this knowledge in other fields (stratigraphy, biogeography, etc.). The last section is a contemporary view on the systematics of trilobites and their position within the Arthropoda.
Morphology of genal caeca in selected trilobites from the Barrandian area
Vyhnánková, Iva ; Fatka, Oldřich (advisor) ; Laibl, Lukáš (referee)
The term "genal caeca" refers to branching and anastomosing ridges developed with varying intensity on free and fixed cheeks and preglabellar field in many trilobites, including the trilobites from Barrandian area of the Czech Republic. This diploma thesis presents the first detailed study of the morphology of genal caeca preserved on cephalons of Cambrian trilobite genera Ptychoparia Hawle & Corda, 1847, Mikaparia Kordule, 2006 and Conocoryphe Hawle & Corda, 1847 from Příbram-Jince and Skryje-Týřovice basins of the Barrandian area. Based on a detailed morphological description and measurements, separate fields of genal caeca occurrence were defined and frequency of their preservation on the studied specimens was compared. The variability of the number of ridges in each field and the frequency of their preservation do not show any convincing connection with cranidial size of the specimens or the locality. Keywords: trilobites, Barrandian area, genal caeca
Ontogeny of selected taxa of middle Cambrian trilobites and agnostoids of the Barrandian area
Laibl, Lukáš ; Fatka, Oldřich (advisor) ; Mergl, Michal (referee) ; Edgecombe, Greg (referee)
This thesis deals with the ontogeny of trilobites and agnostids from the Cambrian of the Skryje-Týřovice and Příbram-Jince basins (Barrandian area, Bohemian Massif). Thesis is presented as a compilation of four papers that were published in scientific peer-reviewed journals. The introduction of the thesis serves as a general overview of the trilobite post- embryonic development and connects all published papers together. All four papers presented here are focussed on modern description of the post-embryonic development of Sao hirsuta, Ptychopariida sp. A, Ptychopariida sp. B, Ptychopariida sp. C, Ellipsocephalus hoffi, Ellipsocephalus polytomus, Hydrocephalus carens and Ecca- paradoxides pusillus. In addition, a discussion about the life-history strategies of early developmental trilobite stages is presented. It has been suggested that Sao hirsuta and Ptychopariida sp. A had benthic protaspides and that the early ontogenetic stages of Ptychopariida sp. B, Eccaparadoxides pusillus and Hydrocephalus carens were likely lecithortophic. Consequently, it has been documented that species with benthic protaspides show a strongly restricted geographic distribution and that lecithotrophic taxa seem to be associated with higher latitude areas. The developmental patterns of Ellipsocephalus hoffi and...
Ontogeny of Sao hirsuta (Barrande, 1846) in the Cambrian of Czech Republic: revision
Laibl, Lukáš ; Fatka, Oldřich (advisor) ; Kleisner, Karel (referee)
The Solenopleurid trilobite Sao hirsuta Barrande, 1846 is known from "Middle" Cambrian sedimentary rocks of the Czech Republic, Germany and Spain. It is one of the first trilobites on which ontogenetic development was described in detail (Barrande, 1852). This diploma thesis is the first modern revision of the ontogeny of this species for more than fifty years. Thesis is primarily based on quantitative methods and a detailed study of morphology of the exoskeleton. Changes in the dorsal exoskeleton during ontogenetic development of S. hirsuta, including the discovery of intrainstar morphological and size variability and the transition from isometric growth to the alometric growth, were described in detail by using quantitative methods (biometric measurements and geometric morphometrics). In the protaspid period different instars of S. hirsuta were recognized. Detailed morphological studies revealed several different morphotypes of protaspid stages. Some of which may represent different taxa. The morphology and the condition of the hypostome was described, including changes of hypostome during ontogeny. The study of segmentation in the species S. hirsuta shows hypoprotomeric development with the initial accumulation phase, middle equilibrium phase and terminal depletion phases. Key words: Sao...
Ontogeny of trilobites
Laibl, Lukáš ; Fatka, Oldřich (advisor) ; Budil, Petr (referee)
The thesis summarizes the current state of knowledge about the ontogeny of trilobites. The introductory chapters describe the basic morphology and anatomy of trilobites, and also mention their ecology, occurrence and feeding habits. In the main part of my thesis, I first summarized the existing research in this area, and also dealt in detail with methods of preservation of trilobite larvae, their reproduction, growth, embryology, postembryonal development, segmentation and ecology. I also mentioned the possible usage of this knowledge in other fields (stratigraphy, biogeography, etc.). The last section is a contemporary view on the systematics of trilobites and their position within the Arthropoda.

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4 Laibl, Lukáš
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