The Koderayama Formation (Miocene, Ishikawa Prefecture) yields a large number of small fossils. Many of them are poorly preserved and difficult to identify, but some are identifiable.We summarize the fossils of sharks of the genus Triakis, which occur most frequently among these small fossils. There are not many data available for the identification of extant sharks of the genus Triakis, however, an attempt was made to identify the sharks of this locality based on the available data.
As a result, we were able to confirm the presence of three species of sharks of the genus Triakis. One species identified in this study is thought to be T. semifasciata and is now found in the waters near land on the western coast of North America, on the opposite side of the Pacific Ocean from Japan.