Matsukawa M., Koarai K., Fukui M., Suzuki K., Ogava Y., Kikukawa S., Kometani M., Hamuro T. A gigantic ammonite from the Upper Jurassic Arimine Formation of the Tetori Group, Japan // Bulletin of the Tateyama Caldera Sabo Museum. 2008. Vol.9. P.1-10. http://www.tatecal.or.jp/proceedings/09-01-10.pdf
This paper devoted to record of the Oxfordian ammonite Kranaosphinctes of the moderate size: it attains slightly more than 25 cm in diameter, which is very common in oxfordian perisphinctids. But this ammonite is biggest one among those recorded from the Tetory Group.
