Late Palaeozoic Tetrapod Biogeography

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The late Palaeozoic represents a crucial period in the development and organisation of terrestrial vertebrate ecosystems. It was at this time that more complex community structures with intricate trophic hierarchies were established in the terrestrial realm. Moreover, the earliest evolution and diversification of amniotes (fully terrestrial tetrapods) occurred with the bifurcation into the two lineages: Synapsida (including mammals) and Sauropsida (including reptiles and birds). Late Carboniferous and Early Permian ecosystems were mostly centred on waterside habitats in a humid equatorial tropical belt. However, towards the end of the Early Permian, substantial changes in terrestrial environments began with the deglaciation of the ice cap at the South Pole leading to climate changes such as the reduction and eventual loss of the tropical everwet belt. Along with this, terrestrial ecosystems for the first time expanded away from the palaeoequatorial regions and into the higher latitude seasonal temperate regions. Although these biogeographic patterns are known, they have never been investigated in a rigorous quantitative framework. The proposed study will test certain hypotheses regarding the early patterns of tetrapod biogeography with cladistic biogeographic methods. For this purpose, selected critical tetrapod taxa from Russia and North America will be taxonomically re-evaluated and included into global phylogenetic analyses to examine the relationships of basal amniotes. In addition, an existing database of tetrapod specimens from the Karoo Basin of South Africa will be updated. Further quantitative analyses will be carried out on both local and global databases to investigate provinciality within and between basins, and the changes in faunal homogeneity through geological time. The results of this research will have important implications for understanding the early biogeographic history of tetrapods and specifically the fully terrestrial amniotes.