Search for dissertations about: "record"

Showing result 6 - 10 of 11431 swedish dissertations containing the word record.

  2. 6. Untangling ambiguities in the microbial fossil record : experimental abiotic and biological approaches

    Author : Sigrid Huld; Anna Neubeck; Sebastian Willman; Sean McMahon; Barbara Cavalazzi; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; chemical gardens; pseudofossils; experimental mineralisation; microbial fossils; methanogens;

    Abstract : Life on early earth has long been the topic of discussion for many researchers: how did it come to be? Which cells came first? Where can we find them? The most ancient rocks on our planet may hold some of the answers to these questions, but many may only be answered in laboratories. Chemical and morphological traces can be found from Archaean deposits, tantalisingly similar to modern day prokaryotes. READ MORE

  4. 7. Decoding the fossil record of early lophophorates : Systematics and phylogeny of problematic Cambrian Lophotrochozoa

    Author : Aodhán D. Butler; Michael Streng; Lars E. Holmer; Russell Garwood; Maggie Cusack; Uppsala universitet; []
    Keywords : 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;

    Abstract : The evolutionary origins of animal phyla are intimately linked with the Cambrian explosion, a period of radical ecological and evolutionary innovation that begins approximately 540 Mya and continues for some 20 million years, during which most major animal groups appear. Lophotrochozoa, a major group of protostome animals that includes molluscs, annelids and brachiopods, represent a significant component of the oldest known fossil records of biomineralised animals, as disclosed by the enigmatic ‘small shelly fossil’ faunas of the early Cambrian. READ MORE

  5. 8. A lake sedimant record from southern Thailand : monsoon variability and ecosystem change since 18 ka

    Author : Camilla Bredberg; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : .... READ MORE

  6. 9. 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

  7. 10. The palaeolimnological record of regime shifts in lakes in response to climate change

    Author : Linda Randsalu Wendrup; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; palaeolimnology; regime shifts; thresholds; alternative stable states; climate change; ecosystem dynamics; diatoms; hydrocarbons; monitoring; lake sediments; shallow lakes; 8.2 ka event;

    Abstract : Regime shifts in lake ecosystems can occur in response to both abrupt and continuous climate change, and the imprints they leave in palaeolimnological records allow us to investigate and better understand patterns and processes governing ecological changes on geological time scales. This thesis aims at investigating palaeolimnological records of regime shifts in lakes during the Holocene to explore how lake ecosystems responded to climate changes and anthropogenic activities and to identify thresholds or tipping points that produced regime shifts. READ MORE