THE THYRA-0 FLORA - TOWARD AN UNDERSTANDING OF THE CLIMATE AND VEGETATION DURING THE EARLY TERTIARY IN THE HIGH ARCTIC

The Late Paleocene-Early Eocene Thyra Ø flora from eastern North Greenland is represented by a collection of 30-31 fossil plant types of which 22-23 are angiosperm leaf types. The flora records warm temperate climatic conditions with the absence of frost and is based mostly on comparison of the nearest living relatives to genera in the Thyra Ø flora. Climatic conditions implied by this method is in contrast to the cool temperate conditions indicated by this method is in contrast to the cool temperate conditions indicated by leaf physiognomy. Unpublished Early Tertiary leaf collections from Spitsbergen also record cool temperate conditions based on leaf margin data even though many taxa representing warmer climatic conditions are present. It is suggested here that the response to the low Arctic light levels was a main factor in shaping the character of the Early Tertiary Arctic vegetation, including leaf physiognomy and species composition. This has implications toward the use of leaf physiognomy for determining past climates in the Arctic. © 1990.