Eocene Mammals from the Akasaki and Nakakoshiki Formations, Western Kyushu, Japan: Preliminary Work and Correlation with Asian Land Mammal Ages
摘要
The earliest known Paleogene mammals from Japan are reported from the Eocene Akasaki Formation, Amakusa area, Kumamoto Prefecture and from the stratigraphically equivalent Nakakoshiki Formation, Koshiki Islands, Kagoshima Prefecture, western Kyushu. Given the occurrences of trogosine tillodonts and brontotheriid perissodactyls, the Akasaki and Nakakoshiki faunas are younger than Bumbanian faunas and are most likely correlated with Arshantan faunas on the Asian mainland. The Japanese faunas contain several new taxa unknown from the Asian mainland, and there are unique faunal combinations in the mammal assemblages.