The first record of an ornithomimosaurian dinosaur from the Upper Cretaceous of Japan

Abstract

Ornithomimosaurs have unusual characters among theropod dinosaurs, and many records of these animals have been reported previously from Asia and North America. However, the fossil record of ornithomimosaurs is limited and was not known from the Upper Cretaceous in Japan despite its many dinosaur discoveries. Here, the first fossil of an ornithomimosaurian dinosaur from the Upper Cretaceous in Japan is described from the Upper Formation of the Mifune Group in Kumamoto Prefecture, Southwest Japan. This new discovery indicates the existence of ornithomimosaurs in the Late Cretaceous coastal areas of East Asia under a semi-arid climate. The occurrences of ornithomimosaur fossils described here are consistent with the presence of many fossil records from a dry climate rather than the humid conditions in the Cretaceous deposits of Asian mainland today.

Keywords::

• Dinosauria
• Ornithomimosauria
• Cretaceous
• palaeobiogeography
• Mifune Group
• Japan

Acknowledgements

This article is part of the doctoral dissertation of the author. I would like to express my gratitude to the members of the committee for the doctoral degree – Yukimitsu Tomida (National Museum of Nature and Science), Harutaka Sakai (Kyoto University), Hiroshi Nishi (Tohoku University), Yoshihiro Kuwahara (Kyushu University) and Masao Ohno (Kyushu University) – for their guidance and encouragement during the Ph.D. project. I am also grateful to Yuji Tomita who donated a specimen for this study. Yoshitsugu Kobayashi (Hokkaido University) and Minoru Tamura (Professor emeritus at Kumamoto University) contributed to this study through instructive discussions and comments. Patrick Leiggi, Carrie Ancell (Museum of the Rockies Montana State University), and two anonymous reviewers also greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author.