An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates.
The biogeographical history of pterosaurs has received very little treatment. Here, we present the first quantitative analysis of pterosaurian biogeography based on an event-based parsimony method (Treefitter). This approach was applied to a phylogenetic tree comprising the relationships of 108 in-group pterosaurian taxa, spanning the full range of this clade's stratigraphical and geographical extent. The results indicate that there is no support for the impact of vicariance or coherent dispersal on pterosaurian distributions. However, this group does display greatly elevated levels of sympatry. Although sampling biases and taxonomic problems might have artificially elevated the occurrence of sympatry, we argue that our results probably reflect a genuine biogeographical signal. We propose a novel model to explain pterosaurian distributions: pterosaurs underwent a series of 'sweep-stakes' dispersal events (across oceanic barriers in most cases), resulting in the founding of sympatric clusters of taxa. Examination of the spatiotemporal distributions of pterosaurian occurrences indicates that their fossil record is extremely patchy. Thus, while there is likely to be genuine information on pterosaurian diversity and biogeographical patterns in the current data-set, caution is required in its interpretation.
Department of Earth Sciences, University College London , Gower Street, London WC1E 6BT , UK.
Paul
P
Upchurch
Department of Geology, University of South Florida , 4202 East Fowler Avenue, SCA528, Tampa , FL 33630 , USA.
Brian
B
Andres
School of Geography, Earth and Environmental Sciences, University of Birmingham , Edgbaston, Birmingham B15 2TT , UK.
Richard J
RJ
Butler
Department of Earth Sciences, The Natural History Museum , Cromwell Road, London SW7 5BD , UK.
Paul M
PM
Barrett
Treefitter; dispersal; diversity; pterosaur; sympatry; vicariance