717. CEPHALOPOD FAUNULE FROM THE CRETACEOUS YATSUSHIRO FORMATION (KYUSHU) AND ITS IMPLICATIONS

Abstract

This is a report on the cephalopod faunule from the Cretaceous Yatsushiro Formation in southwestern Kyushu. It consists of 5 species from three localities, which are assigned to the middle part of the Yatsushiro Formation. One is a new species of Heminautilus, a peculiar nautiloid which deviates much in shell-form from H. saxbii (MORRIS), being apparently similar to certain species of Paracenoceras. Others are ammonites, Brewericeras n. sp., allied to B. hulenense (ANDERSON) from the Pacific Coast of North America, Prolyelliceras (?) sp., Epileymeriella aff. hitzeli (JACOB) and Platiknemiceras n. sp., allied to P. gracile (DOUVILLE). Palaeontological descriptions are given by the senior author. The faunule is interesting in that both the North Pacific and the Tethys Sea elements intermingled. The ammonites indicate the Lower Albian. As the Yatsushiro Formation contains land flora and some non-marine to brackish water molluscs in its lower and upper parts, the cephalopod faunule gives a key to correlate the fossils of different facies.