Comparison of Korean and Japanese Tertiary fossil wood floras with special references to the genusWataria

Abstract

Among 64 fossil woods collected from the Upper Coal-bearing Formation of Janggi Group, Pohang, Korea, four specimens have been characterized by their distinct ring porosity and the presence of tile cells in rays. After detailed anatomical studies, we could identify them as two species ofWataria-W. miocenica andW. parvipora. GenusWataria, known as an extinct taxon of Sterculiaceae, has been found only in the Tertiary formations in Japan. Most of these sterculiaceous plants are thermophilic and reportedly never inhabited in the Korean Peninsula. The existence of fossil woods ofWataria in Korea supports the idea of a common flora established in both countries during the Tertiary. In Japan, fossil woods ofWataria have been found only during the early Miocene formations. Therefore, the age of the Upper Coal-bearing Formation can be said of as the early Miocene.