Sökning: "Natural Sciences Earth and Related Environmental Sciences Geology"

Visar resultat 6 - 10 av 586 avhandlingar innehållade orden Natural Sciences Earth and Related Environmental Sciences Geology.

  1. 6. Origin and Lifestyles of early Brachiopods and other Lophotrochozoans : Insights from the Chengjiang and Guanshan Fossil-Lagerstätten

    Författare :Haizhou Wang; Lars E. Holmer; Zhifei Zhang; Michael Streng; David A.T. Harper; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cambrian Explosion; Chengjiang; Guanshan; Lagerstätten; Lophotrochozoa; Brachiopoda; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    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

  3. 7. Exceptionally Preserved Cambrian Lophotrochozoa : Taxonomy, Systematics and Taphonomy of Chengjiang and Indian Springs Lophophorates

    Författare :Aodhán D. Butler; Michael Streng; Lars E. Holmer; Christian Skovsted; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Brachiopoda; Chengjiang; Lagerstätte; Cambrian Explosion; palaeobiology; stem-group; entoproct; phoronid; tommotiid; exceptional preservation.; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    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

  4. 8. Early Cambrian Problematic Lophotrochozoans and Dilemmas of Scleritome Reconstructions

    Författare :Cecilia M Larsson; Lars E Holmer; Christian B Skovsted; Anette E S Högström; John S Peel; Glenn A Brock; Michael J Vendrasco; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Problematica; scleritome; Trachyplax; tommotiid; Cambrian; South Australia; North Greenland; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    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

  5. 9. In the wake of deglaciation - sedimentary signatures of ice-sheet decay and sea-level change : Studies from south-central Sweden and the western Arctic Ocean

    Författare :Henrik Swärd; Matt O'Regan; Martin Jakobsson; Juha Pekka Lunkka; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; paleoenvironmental changes; last deglaciation; sedimentology; Lake Vättern; western Arctic Ocean; Mackenzie Trough; Herald Canyon; Marine Geology; maringeologi;

    Sammanfattning : Lacustrine and marine sedimentary archives help unravel details concerning the withdrawal of large ice sheets and resulting sea-level changes during the last deglaciation (22 -11 kyr). In a series of four manuscripts, this PhD thesis investigates the sedimentological signatures from deglacial processes at three key locations in the northern hemisphere: (i) Lake Vättern (LV) in south-central Sweden, (ii) Herald Canyon (HC) in the western Chukchi Sea, and (iii) Mackenzie Trough (MT) on the westernmost edge of the Canadian Beaufort Shelf. LÄS MER

  7. 10. Quaternary paleoceanography of the Arctic Ocean : A study of sediment stratigraphy and physical properties

    Författare :Emma Sellén; Martin Jakobsson; Jan Backman; Dorthe Klitgaard-Kristensen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Arctic Ocean; sedimentology; Quaternary; stratigraphy; physical properties; Earth sciences; Geovetenskap; Quaternary geology; Kvartärgeologi; Sedimentology; Sedimentologi; Marine Geoscience; marin geovetenskap;

    Sammanfattning : A Quaternary perspective on the paleoceanographic evolution of the central Arctic Ocean has been obtained in this PhD thesis by studying sediment cores from all of the Arctic’s major submarine ridges and plateaus. The included cores were mainly recovered during the Healy-Oden Trans-Arctic expedition in 2005 and the Lomonosov Ridge off Greenland expedition in 2007. LÄS MER