Fossilized cusps of Chlamydoselachus anguineus Garman, 1884 were found from the Miocene Haratashino Formation. Those cusps were classified into three types based on the surface conditions. For identification of those fossil cusps, they were compared with those of the teeth of Chlamydoselachus anguineus,a male of 136 cm total length.

Frilled Shark, Chlamydoselachus anguineus, a male of 129 cm total length.

Cutting edges and folds on the teeth from Recent Frilled Shark

Upper and lower teeth at the same position number from Chlamydoselachus anguineus, a male of 136 cm TL showed almost the same surface pattern of cutting edges and folds. Every three cusps of one tooth also possess almost the same surface pattern.
Cutting edges: UR1 showed incomplete cutting edges. All other teeth possess complete or near complete cutting edges.
Folds: In labial view, UR1-UR7 showed smooth faces, UR8-UR10 showed folds which become progressively stronger and longer with distance from the jaw symphysis. In lingual view, UR1-UR4 showed smooth faces, UR5-UR10 showed folds which become progressively stronger and longer with distance from the jaw symphysis.

Dentition of Chlamydoselachus anguineus, a male of 136 cm total length.

Cutting edges and folds on the fossil cusps from the Haratashino Formation

Three types of cusps of Chlamydoselachus anguineus were found from the Haratashino Formation. Type A; complete cutting edges and smooth faces, Type B; complete cutting edge and folds on the labial face,. Type C; complete cutting edge and folds on both faces. Judging from the surface patterns of each type, type A, B, and C were assigned to be anterior, lateral and posterior tooth of Chlamydoselachus anguineus, respectively.

Tree types of cusps from the Miocene Haratashino Formation. Type A; smooth cusp with complete cutting edges, Type B; cusp with folds on the labial face. Type C; cusp with folds on both faces

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