1999 Volume 6 Issue 2 Pages 49-62
Late Pliocene plant macrofossil assemblages on Awaji Island, central Japan, were studied to reconstruct the habitat of plants and to complement the upper Pliocene biostratigraphy of the Osaka Group. The lower part of the Atago Formation yields many plants extinct from Japan and includes Choerospondias axillaris and Reevesia sp. that characterize the basal part of the Osaka Group in the Sennan area. Stratigraphic occurrence of plant fossils in the upper Pliocene on Awaji Island is very similar to that in the Sennan area. Sedimentary facies of fossil bearing beds were classified into three types, i.e., peat, massive silt, and stratified sand, and occurrence of plant taxa was compared between these types to reconstruct their habitat. Glyptostrobus pensilis, Trapa and Nymphaeaceae included in peat were growing in backmarshes in an alluvial plain. Plants common in massive silt, such as Metasequoia glyptostroboides, Stewartia monadelpha, Sequoia sp., and Pseudolarix amabilis, composed forests in wetlands and on sandbanks in an alluvial plain. Plants common in stratified sand, such as Picea sect. Picea, Buxus microphylla, and Fagus microcarpa, grew on fans and mountain slopes around a sedimentary basin.
