Early Tithonian (Late Jurassic) Ammonite Parapallasiceras newly discovered from the Itoshiro Subgroup (Tetori Group) in the Hida Belt, northern Central Japan

Abstract

Early Tithonian (Late Jurassic) ammonite Parapallasiceras cf. pseudocontiguum (Donze and Enay) was discovered in situ from the Kamihambara Formation of the Itoshiro Subgroup (Tetori Group) distributed in the Hida Belt, in Fukui Prefecture, northern Central Japan. It is a Perisphinctid characterized by polygyrate ribbing and can be compared to the said species originally described in Southeast France. The species occurs in the Lower Tithonian of the Submediterranean region. Therefore at least a part of the Itoshiro Subgroup can be dated Early Tithonian, judged by this ammonite. (Communicated by Tatsuro MATSUMOTO, M.J.A.)