NEW APPROACHES FOR QUANTIFYING THE CRETACEOUS TERRESTRIAL CLIMATE RECORD

Abstract

Climatic variability is reviewed, as recorded in the terrestrial record of the Cretaceous and with particular emphasis of newer techniques and advances. Physiognomic analysis of flora from the high latitude sites of the Northern and Southern Hemispheres has provided extensive evidence for warm polar climates and for a gradual decline in terrestrial mean annual temperatures as the Cretaceous drew to a close. These data are largely consistent with the marine record although the limited data available for the Arctic Ocean may require a fuller evaluation of its val- idity and significance. Climate-related geochemical variations in sediments and phosphate oxygen isotope analysis of continental vertebrates are also consistent with Mid-Cretaceous polar warmth followed by Late Cretaceous cooling. Considerably less quantitative data have been derived from tropical palaeolatitudes. Nevertheless, available data indicate a warm to hot, semi-arid low latitude Cretaceous climate. An apparent lack of a tropical everwet zone results in limited tropical rainforest biomes, which are restricted to a narrow palaeoequatorial belt.