The palaeoclimate of the Karoo: evidence from plant fossils

The common and conspicuous Karoo fossil floras flourished in what appears to be climatically disadvantageous conditions, as southern Gondwana lay within the Antarctic Circle throughout much of the Permian. Most previous climatic reconstructions suggest a cold-temperate climate. Plant structures are sensitive to environmental conditions, particularly climate, and may be used to predict these conditions. Large Glossopteris leaves dominate fossil plant assemblages, and considerable deposits of coal were laid down at this time. Quantitative analyses of fossil leaves from three coeval localities indicate that the climate prevailing at the time of the burial of these Glossopteris floras was seasonal, with summer conditions extremely favourable for plant growth, comparable to tropical regions today, and winters that were also correspondingly warmer than has previously been suggested.