Quantitative estimates of terrestrial paleotemperatures near the North Pole were derived from the physiognomy of the vegetation, including leaf-margin analysis, from rocks of latest Albian and Late Cretaceous age of the North Slope of Alaska. During the latest Albian and Cenomanian, mean annual temperature was approximately 10 ±3 °C. During the Coniacian, mean annual temperature may have been 2-3 °C warmer than during the Albian-Cenomanian but no higher than 13 °C. During the Campanian and Maastrichtian, mean annual temperature would have been about 2-8 °C. Although the ranges for the individual estimates overlap, differences among the floras indicate that the relative changes in mean annual temperature did occur.