2020 Volume 107 Pages 21-26
In the children’s story “Naranoki daigakushi no nojuku” of Mr. Kenji Miyazawa (a well-known Japanese poet and author of children’s stories; 1896–1933), Naraonki daigakushi or Bachelor Naranoki, the main character of the story, met a herd of Brontosaurus at the sea coast of Cretaceous age. Since Brontosaurus was generally considered as a Late Jurassic dinosaur, and Mr. Miyazawa learned the geology and soil science in the Morioka Imperial College of Agriculture and Forestry, the age assignment of Brontosaurus to the Cretaceous in Mr. Miyazawa’s work is curious. Survey of contents of Japanese books on historical geology and paleontology reveals that the Morrison Formation and Morrison dinosaurs including Brontosaurus were generally considered to be of Cretaceous age in almost all references published in the Taisho and the early Showa eras (corresponding to years 1918 to around 1950) of Japan. In USA, Cretaceous age of the Morrison Formation was frequently discussed from 1911 to 1916. It is supposed that this information was received by Japanese paleontologists promptly, and widely known probably through the textbooks on historical geology “Zensekaishi (1918)” and/or on paleontology “Koseibutsugaku kouyou (1920)”, both of which were written by Professor Matajiro Yokoyama. Although the age of the Morrison Formation was reassigned to the Late Jurassic in 1918 in USA, the acceptance of the revision of the geological age was delayed in Japan, and it was not until early 1950’s that the revision was broadly accepted in Japan, when the textbook on historical geology “Chishigaku (1952–1953)” by Professor Tatsuro Matsumoto and his colleagues was published. Mr. Miyazawa was probably one of those who are keen to acquire state-of-the-art information on geology and paleontology at that time, and it seems reasonable to consider that “Naranoki daigakushi no nojuku” was written while the period of Brontosaurus was believed as the Cretaceous in Japan.
