Middle Devonian brachiopods from the Nakazato Formation, South Kitakami Belt, northeast Japan and their palaeobiogeographical affinity with those of western Inner Mongolia

Abstract

A Middle Devonian (Eifelian) brachiopod fauna, the Nakazato fauna, from the upper part (N 3 Member) of the Nakazato Formation in the Hikoroichi area, South Kitakami Belt, northeast Japan, consists of 22 species belonging to 22 genera. Among the species of the Nakazato fauna, 8 species have been found also from the top of the Yikewusu Formation (Upper Eifelian) in the Zhusilenghaierhan area, western Inner Mongolia. There was probably a close biogeographical connection between the South Kitakami and western Inner Mongolian regions in the early Middle Devonian (Eifelian) time.