2013 年 119 巻 9 号 p. 647-652
This paper reports on latest Late Jurassic to early Late Cretaceous radiolarians extracted from a gravel of calcareous nodule that originated from the basal conglomerate of the Pliocene Naarai Formation. The calcareous nodule (ca. 12 cm in length) contains vertebrate bones, and lithologically similar gravels have been known to contain Albian and Tithonian ammonoids. The age of the radiolarians from the calcareous nodule ranges from latest Tithonian to late Cenomanian, based on the occurrence of Holocryptocanium barbui. This age range is concordant with ammonoid ages reported previously from gravels of calcareous nodules derived from the Naarai Formation.