Abstract
Newly found fossil shark teeth of a sleeper shark are described. This is probably an undescribed species of the genus Centroselachus belonging to the Family Somniosidae. These fossil teeth were discovered from the Middle Miocene Iseyama Formation (Northern Fossa Magna Region), Ueda City, Nagano Prefecture, central Japan. These teeth indicate the shape of a part of a symphysial tooth row, which belong to a left side of parasymphysial teeth and a left first anterior tooth. Judging from the main characters of a parasymphysial tooth, such as distal and mesial blades presented both joining in a notch, it is considered that the tooth differs from teeth of the genus Centroscymnus. This fossil is identified as the genus Centroselachus sp.. This paper constitutes the first fossil record of the genus Centroselachus from the Miocene of Japan.
