Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum Vol. 50, No. 3 Research reports of the “Paleoparadoxiid Mizunami-Kamado specimen”

The pollen assemblage from the sediment sample containing the whole skeleton of a paleopara-doxiid (“Mizunami-Kamado specimen”), is mainly composed of Pinus, Dacrydium, Quercus (evergreen type) and others. This assemblage includes warm elements such as Keteleeria, Pseu-dolarix, Quercus (evergreen type), Dacrydium, Liquidambar, and Reevesia, many of them are now extinct in Japan. The assemblage is comparable with the pollen assemblages previously documented from the Shukunohora Formation, Mizunami Group, Gifu Prefecture, Japan. These assemblages correspond to the NP-2B pollen zone, indicative of the Middle Miocene climatic optimum. The paleovegetation is inferred to be evergreen conifer forests characterized by Pinus and Dacrydium with evergreen broad-leaved trees such as evergreen Quercus and deciduous broad-leaved trees. The paleoclimatic conditions are estimated to be about 21°C for the annual mean temperature with an annual precipitation of 1,500–1,800 mm. Similar pollen assemblages found in sediments containing Paleoparadoxia in Niigata and Okayama prefectures also repre-sent the NP-2B pollen zone and include mangrove plant pollen fossils.