Search for dissertations about: "historical morphology"
Showing result 16 - 20 of 29 swedish dissertations containing the words historical morphology.
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16. The origin of the marine Lockne impact structure, Jämtland
Abstract : The Lockne impact structure in Jämtland (63o00'20"N, 14o49'30"E), formed in the Middle Ordovician at approximately 455 Ma. The structure is a concentric crater with a total diameter of 13.5 km. The impact took place in a marine environment. READ MORE
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17. Fossil birds: Contributions to the understanding of avian evolution
Abstract : The study of the evolution of birds began about 150 years ago with the finding of Archaeopteryx. Yet, many unsolved questions about avian evolution remain to be answered. This thesis aims at addressing some of these questions.The Early Cretaceous Confusiusornis is the most well-represented Mesozoic bird in the fossil record. READ MORE
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18. Evolution and taxonomy of Cambrian arthropods from Greenland and Sweden
Abstract : Arthropods have a rich fossil record spanning the Phanerozoic. Biomineralized forms such as the extinct trilobites are particularly common and are proven index fossils for biostratigraphy. Forms with an unmineralized cuticle are more rare, preserved only in so called konservat lagerstätten. READ MORE
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19. Evolution and ecology of Baltic late Ordovician univalved molluscs
Abstract : Univalved molluscs (Gastropoda and Tergomya) are common fossils in the Palaeozoic succession across Baltoscandia, but most of the more embracive descriptive works on this group appeared before or near the turn of the 19th century. The study presented here aims at revision and description of some Baltoscandian late Ordovician/early Silurian univalved molluscs with emphasis on their shell morphology. READ MORE
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20. Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
Abstract : One of the most important events in the history of life is the evolution of the complex, eukaryotic cell. The eukaryotes are complex organisms with membrane-bound intracellular structures, and they include a variety of both single-celled and multicellular organisms: plants, animals, fungi and various protists. READ MORE