Abstract
Middle Permian ammonoid faunas are recognized from the Hosoo and Kamiyasse Formations in the Kamiyasse-Imo district, north of Kesennuma, Southern Kitakami Massif, Northeast Japan. The faunas comprise the following genera: Parastacheoceras, Demarezites, Demarezites?, Waagenoceras, Timorites, Tauroceras?, Cardiella, Adrianites, Agathiceras, Agathiceras?, Paracettites and Cibotites. Parastacheoceras bidentatus gen. and sp. nov. is newly proposed. The genera Demarezites, Tauroceras, Cardiella and Adrianites are described for first time from Japan. Based on these ammonoids, the middle part of the Hosoo Formation, upper part of the Hosoo Formation to the lower middle part of the Kamiyasse Formation, and upper middle part of the Kamiyasse Formation are correlatable with the Middle Permian Roadian, Wordian and Capitanian, respectively. The discovery of genera Demarezites and Cardiella strongly supports the previous hypothesis that the South Kitakami Paleoland was located in the equatorial province during the Middle Permian.
