Sökning: "Historisk geologi och paleontologi"
Visar resultat 1 - 5 av 26 avhandlingar innehållade orden Historisk geologi och paleontologi.
1. Late Eocene through Oligocene calcareous nannofossils from the paleo-equatorial Pacific Ocean – taxonomy, preservation history, biochronology and evolution
Sammanfattning : This study aims to unravel the ecological and evolutionary dynamics within the calcareous nannofossil communities at the Eocene/Oligocene (E/O) transition and during the Oligocene time when Cenozoic 'icehouse' conditions were established. The main question this study aims to answer is whether the changes in the nannofossil assemblages were controlled by intrinsic evolutionary trends or if the changes were controlled by environmental factors such as changes in temperature and nutrient availability in the surface water. LÄS MER
2. Exceptionally Preserved Cambrian Lophotrochozoa : Taxonomy, Systematics and Taphonomy of Chengjiang and Indian Springs Lophophorates
Sammanfattning : The origin and evolution of Lophotrochozoa can be traced to the plethora of lower Cambrian scleritome taxa. We aim to determine the character suites linking these stem-Lophotrochozoa to their extant crown relatives, in particular the small shelly tommotiids and the stem-group brachiopods. LÄS MER
3. Early Cambrian Problematic Lophotrochozoans and Dilemmas of Scleritome Reconstructions
Sammanfattning : The emergence and radiation of metazoan body plans around the Precambrian/Cambrian boundary, some 500-600 million years ago, seems to be concordant with the appearance and diversification of preservable hard parts. Several Precambrian soft-bodied, multicellular organisms most likely represent stem-group bilaterians, but their fossil record is rather sparse. LÄS MER
4. Origin and Lifestyles of early Brachiopods and other Lophotrochozoans : Insights from the Chengjiang and Guanshan Fossil-Lagerstätten
Sammanfattning : One of the great unsolved evolutionary questions concerns the origin and phylogeny of the major animal phyla that appeared in the fossil record more than 540 million years ago, during the Cambrian explosion. Although new molecular information has been very useful, we still have little understanding about the origin of most of the phyla of bilaterians living today. LÄS MER
5. Shipborne geophysical study of an Ordovician-Silurian carbonate platform, Fårö - Hiiumaa area, northeastern Baltic Sea
Sammanfattning : The lithological-stratigraphical subdivision, the internal structure and the present relief of the Lower Paleozoic bedrock sequence was investigated by means of high resolution shallow marine seismic reflection profiling in the northeastern Baltic Sea.The Cambrian, as well as the lowermost Silurian layers, show rapidly changing lithologies and thicknesses and provide no trans-Baltic seismic reflectors. LÄS MER
