The Lower Triassic Kurotaki Fauna in Shikoku and its allied Faunas in Japan

Abstract

This article treats with the description mainly of the Lower Triassic fossils from the Kurotaki limestone in Shikoku, southwest Japan, which have long been left undescribed. Of the Kurotaki fauna, ten species of bivalves, two species of gastropods, and one sepcies each of ammonite and brachiopod are discriminated. The Kurotaki limestone is considered, from these fossils, to be Mid-Skythian, probably early Owenitan in age. The presence of "Streblochondria" matsushitai n. sp. and Plicatifera? sp. indicates a survival of the Paleozoic elements in the eraly Triassic. Reexamining other lower Triassic faunas, taxonomic emendation has also been made. Lastly the middle Skythian transgression in Japan has been suggested by reviewing the lower Triassic System in Japan.