Sökning: "Per Ahlberg"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden Per Ahlberg.

  1. 1. New structures, reactions, mechanisms and methods in carbonium ion and carbanion chemistry

    Författare :Per Ahlberg; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : .... LÄS MER

  3. 2. 100 million years of shark macroevolution : A morphometric dive into tooth shape diversity

    Författare :Mohamad Bazzi; Per Ahlberg; Matt Friedman; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sharks; Macroevolution; Extinction recovery dynamics; Geometric Morphometrics; Morphospace-Disparity Framework; Teeth; Biology with specialization in Evolutionary Organismal Biology; Biologi med inriktning mot evolutionär organismbiologi;

    Sammanfattning : Few vertebrate clades exhibit the evolutionary longevity and versatility of sharks, which constitute nearly half of all current chondrichthyan biodiversity and represent an ecological diversity of mid-to-apex trophic-level predators in both marine and freshwater environments. The rich fossil record of shark teeth from Mesozoic and Cenozoic rocks also makes the group amenable to large-scale quantitative analyses. LÄS MER

  4. 3. The Origin of Tetrapod Limbs and Girdles: Fossil and Developmental Evidence

    Författare :Catherine Anne Boisvert; Per Erik Ahlberg; Rolf Ohlsson; Johan Ledin; Lennart Olsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organism biology; Organismbiologi;

    Sammanfattning : Around 375 million years ago, the first tetrapods appeared, marking one of the most important events in vertebrate evolutionary history. The fin to limb transition saw the appearance of fingers and a weight bearing pelvic girdle. LÄS MER

  5. 4. Endocranial Morphology and Phylogeny of Palaeozoic Gnathostomes (Jawed Vertebrates)

    Författare :Martin D. Brazeau; Per Ahlberg; Graham Budd; Henning Blom; Michael Coates; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; systematics; palaeontology; anatomy; evolution; Organism biology; Organismbiologi;

    Sammanfattning : Gnathostomes, or jawed vertebrates, make up the overwhelming majority of modern vertebrate diversity. Among living vertebrates, they comprise the chondrichthyans (“cartilaginous fishes” such as sharks, skates, rays, chimaeras) and the osteichthyans (“bony fishes” or bony vertebrates, inclusive of tetrapods). LÄS MER

  7. 5. Geology, stratigraphy, and fossil vertebrates of Gotland, Sweden : a review

    Författare :Oskar Bremer; Henning Blom; Per Ahlberg; Märss Tiiu; Jan Ove Ebbestad; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Silurian; Gotland geology; Baltic Basin; extinction events; isotope excursions; atmospheric and oceanic cycles; early vertebrates; scale taxonomy; environmental preferences; vertebrate biozonation.; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    Sammanfattning : The Silurian limestones of Gotland, Sweden, and their exceptionally well-preserved fossils have attracted the interest of scientists for more than 200 years. The sedimentary rocks represent approximately 10 million years of time, and were deposited in a shallow, equatorial inland sea named the Baltic Basin. LÄS MER