The Fossil Flora of the Paleogene Climatic Optimum in North Eastern Asia

Abstract

The wide distribution of a thermophilic flora in north-eastern Asia during the Eocene is a striking and somewhat unexpected feature in the history of the palaeoflora of this region. Since the end of the Late Cretaceous and the beginning of the Paleogene there was a temperate mesophilic deciduous flora of the ancient Arctic type. But in the Middle Eocene sharp changes occurred in the systematic composition of floristic assemblages. This was the result of extensive invasions of warm-adapted plants (including of the palm Sabal) that had been caused by the global warming of climate. The thermophilic element of apparently North American origin migrated via Beringia to north-eastern Asia. But at the end of the Middle Eocene the thermophilic flora died out almost entirely and was replaced by a temperate mesophilic flora of a coniferous — broad-leaved type. Cooperative international exploration of these palaeofloras of the climatic optimum would help clarify our understanding of the history of the plant kingdom, improve palaeoclimatic and palaeogeographic reconstructions and assist in solving practical aspects of eco- and phytostratigraphy of the continental deposits involved.