Late Cretaceous platanoids from the Mifune Group of Kyushu, Southwest Japan—Revisiting the early paleobotanical collection in the National Museum of Nature and Science

Abstract

One of the earliest plant fossil specimens in the National Museum of Nature and Science collection was systematically studied, and its history was reviewed. The specimen is a sandstone block from Mifune in Kumamoto Prefecture, Southwest Japan, yielding five “platanoid” leaves scattered on the mudstone cap. Variably oriented leaves from the same species suggest that they were deposited parautochthonously. The leaves were identified as Ettingshausenia cuneifolia (Bronn) Stiehler, which were common on the Eurasian continent during the Cenomanian–Turonian age of the Late Cretaceous. To our knowledge, this is the southernmost record of this species in Far East Asia. The lithological features of the specimen and age range of the fossil species are concordant with those of the Upper Formation of the Mifune Group (Turonian–Coniacian). We confirmed the occurrence of this species in several localities. Although the timing of collection and collector (s) remains unclear, we assumed that the specimen was collected after the initial paleobotanical work by a Swedish paleobotanist A. G. Nathorst in 1888, who first reported the fragmentary specimens of the Mifune Group sent by E. Naumann and M. Yokoyama of the Geological Survey of Japan in 1884.