
Alexander BjarnasonUniversity of Oxford | OX · Department of Earth Sciences
Alexander Bjarnason
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16
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Publications
Publications (16)
Characterizing how variation in the tempo and mode of evolution has structured the phenotypic diversity of extant species is a central goal of macroevolution1–3. However, studies are typically limited to a handful of traits4–6, providing incomplete information. We analyse morphological diversification in living birds, an ecologically diverse group⁷...
The Early Cretaceous diversification of birds was a major event in the history of terrestrial ecosystems, occurring during the earliest phase of the Cretaceous Terrestrial Revolution, long before the origin of the bird crown-group. Frugivorous birds play an important role in seed dispersal today. However, evidence of fruit consumption in early bird...
The Early Cretaceous diversification of birds was a major event in the history of terrestrial ecosystems, occurring during the earliest phase of the Cretaceous Terrestrial Revolution. Frugivorous birds play an important role in seed dispersal today, and may have done so since their origins. However, evidence of this has been lacking. Jeholornis is...
Birds show tremendous ecological disparity in spite of strong biomechanical constraints imposed by flight. Modular skeletal evolution is generally accepted to have facilitated this, with distinct body regions showing semi-independent evolutionary trajectories. However, this hypothesis has received little scrutiny. We analyse evolutionary modularity...
Invasive alien species cause major changes to ecosystem functioning and patterns of biodiversity, and the main factors involved in invasion success remain contested. Using the Mediterranean island of Crete, Greece as a case study, we suggest a framework for analyzing spatial data of alien species distributions, based on environmental predictors, ai...
Pitheciids, one of the major radiations of New World monkeys endemic to South and Central America, are distributed in the Amazon and Orinoco basins, and include Callicebus, Cacajao, Chiropotes, and Pithecia. Molecular phylogenetics strongly support pitheciid monophyly, whereas morphological analyses infer a range of phylogenies including a sister r...
Reconstructing evolutionary relationships of living and extinct primate groups requires reliable phylogenetic inference based on morphology, as DNA is rarely preserved in fossil specimens. Atelids (family Atelidae) are a monophyletic clade and one of the three major adaptive radiations of south and central American primates (platyrrhines), includin...
Many phylogenetic relationships based on morphology were rejected following the molecular revolution, yet there is a need for phylogenetic analysis of morphology that reliably infers phylogenetic relationships so that we can understand the evolutionary relationships of extant and fossil taxa. I use geometric morphometric and distance-based phylogen...
The evolutionary relationships of extant great apes and humans have been largely resolved by molecular studies, yet morphology-based phylogenetic analyses continue to provide conflicting results. In order to further investigate this discrepancy we present bootstrap clade support of morphological data based on two quantitative datasets, one dataset...
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