Article: Mid Mesozoic floras and climates

Multivariate statistical analyses of pollen and spore assemblages from Late Triassic to Early Cretaceous sedimentary strata in north-west Europe and earlier Jurassic deposits in Western Australia have allowed the identification of three major climatic-ecological groupings in each area. In each hemisphere the sporomorph groupings are interpreted as reflecting semi-tropical, cool-temperate, and intermediate climatic conditions. Only about 8 per cent, of the pollen and spore taxa occur in both hemispheres; among these, there is a high degree of consistency in climatic-ecological behaviour between north and south. When the constituents of the groups are plotted as summary pollen diagrams in the conventional Quaternary palynological manner, climatic 'fingerprints' emerge which allow correlations of hitherto unprecedented accuracy, whether within a region or between hemispheres. The changing proportions of the different groupings allow the first pollen-based quantitative reconstructions of Jurassic climates to be made.