Search for dissertations about: "paleontology"

Showing result 1 - 5 of 20 swedish dissertations containing the word paleontology.

  1. 1. Ocean chemistry and the evolution of multicellularity

    Author : Emma U. Hammarlund; Stefan Bengtson; Donald Canfield; Nils Holm; Graham Budd; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; biology; paleontology; evolution; multicellularity; geokemi; Geochemistry;

    Abstract : Oxygen has been assumed to be a vital trigger for the evolution of multicellular life forms on Earth, partly based on its power to promote substantial energy flux in cell respiration and partly as biosynthesis of compounds like collagen require oxygen. However, the co-evolution of large life and the Earth’s chemical environment is not well understood at present, and there is particular disagreement in the field about whether the Cambrian explosion of animal life forms was a chemical or biological event. READ MORE

  2. 2. Development and three-dimensional histology of vertebrate dermal fin spines

    Author : Anna Jerve; Per Erik Ahlberg; Martin Brazeau; Tatjana Haitina; Philippe Janvier; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; fin spine; paleontology; early vertebrate; histology; development; Biology with specialization in Evolutionary Organismal Biology; Biologi med inriktning mot evolutionär organismbiologi;

    Abstract : Jawed vertebrates (gnathostomes) consist of two clades with living representatives, the chondricthyans (cartilaginous fish including sharks, rays, and chimaeras) and the osteichthyans (bony fish and tetrapods), and two fossil groups, the "placoderms" and "acanthodians". These extinct forms were thought to be monophyletic, but are now considered to be paraphyletic partly due to the discovery of early chondrichthyans and osteichthyans with characters that had been previously used to define them. READ MORE

  3. 3. Early–Middle Ordovician biotic and sedimentary dynamics in the Baltoscandian paleobasin

    Author : Anders Lindskog; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ordovician; ‘orthoceratite limestone’; carbonate sedimentology; microfacies; paleoecology; paleoenvironment; paleontology; Baltoscandia;

    Abstract : The Baltoscandian region forms part of the paleocontinent Baltica, which was largely covered by a shallow epeiric sea throughout much of the Ordovician (c. 485.5–444 Ma). This ancient sea is today recorded by a thin succession of sedimentary rocks. READ MORE

  4. 4. Preservation of Marine Reptile Soft Parts: Reconstructing the Life and Death of Ancient Leviathans

    Author : Randolph De La Garza; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Molecular paleontology; Taphonomy; Soft-tissues; Lagerstätten; Skin; Sea Turtle; Ichthyosaur; Fur Formation; Posidonia Shale; Paleobiology; Marine Reptiles;

    Abstract : Marine reptiles constitute a diverse group of secondarily aquatic tetrapods that have inhabited the world’s oceans for the greater part of the last 250 million years. While certain large-scale anatomical changes have been observed through progressive alterations of their skeletal morphology (e.g. READ MORE

  5. 5. Origin and the evolution of diatoms through the integration of paleontology and phylogenetics

    Author : Karolina Brylka; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; diatoms; evolution; fossil record; Cretaceous; molecular evolution; Mesozoic; silicon transporter proteins; gene duplication;

    Abstract : Diatoms, the prominent photosynthetic eucaryotes, have inhabited the world’s oceans for at least the past 120 Ma since their first appearance in the Lower Cretaceous. There are also records of older diatoms, from the Jurassic dating to ca. 172 Ma and ca. 165 Ma, however these are poorly documented. READ MORE