Yoshihiro Tanaka. Numata Fossil Museum, 2-7-49, Minami 1, Numata Town, Hokkaido, 078-2225 Japan, and Hokkaido University Museum, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 Japan
Yoshi Tanaka received his Ph.D. from the University of Otago, New Zealand. He is a curator at Numata Fossil Museum, Hokkaido, Japan and also a researcher at Hokkaido University Museum. He works on the morphology and phylogeny of marine mammals (dolphins, porpoises, whales and walruses) from Japan and New Zealand. This paper is a part of his research project at Numata Town.
Hiroto Ichishima. Fukui Prefectural Dinosaur Museum, Terao 51-11, Muroko, Katsuyama, Fukui 911-8601, Japan,
Hiroto Ichishima received his Ph.D. from the University of Otago, New Zealand. He is currently a senior curator at Fukui Dinosaur Museum in Japan. He has worked on fossil cetaceans from Hokkaido, the northernmost island of Japan. His research interest includes vertebrate paleontology, whale anatomy, and evolution.