Report of an allodesmine humerus from Shimane, Japan: summary of Japanese allodesmines

A new specimen of a pinniped humerus was found from the middle Miocene Fujina Formation, Shimane, Japan. It was identified as Allodesminae gen. et sp. indet. based on morphological description and comparisons with allodesmine humeri. The results of the comparisons suggest that there is variation in morphological features within this group. This discovery that revealed allodesmines had already expanded along the north-to-south coastal regions from the early stage of the back-arc spreading of the Sea of Japan. According to the summary of Japanese allodesmines, these pinnipeds thrived in the Japanese coastal regions during the middle to late Miocene as well as in North America.