Early Cretaceous terrestrial palynomorph assemblages from the Miyako and Tetori Groups, Japan, and their implication to paleophytogeographic provinces

Abstract

Terrestrial palynomorph assemblages were found from the Lower Cretaceous Miyako Group in the Tanohata area, northeast Japan, and the Tetori Group in the Kuzuryu area, central Japan. There is no obvious difference between the assemblages from these two localities, although these localities have been regarded as belonging to different paleophytogeographic provinces in East Asia on the basis of the plant megafossils. This result is consistent with the suggestion by the recent reconsideration on the megafossil flora from the Tetori Group that the paleophytogeographic provincialism might have weakened during middle to late Early Cretaceous time. The terrestrial palynomorph assemblage from the Miyako Group has characters of both of Cerebropollenites and Schizaeoisporites palynofloras, which were proposed by previous studies, in the Northern Hemisphere during the Early Cretaceous time. This suggests an overlooked transitional palynofloral province between the Cerebropollenites and Schizaeoisporites palynofloral provinces in continental margin of Eurasia during that time.