Several teeth of the Japanese bullhead shark (Heterodontus japonicus) were collected from the "naarai" Formation in Chiba Prefecture, Japan. These teeth were not well preserved, but many of them were large. It was very interesting to find out how long the shark with the largest tooth was. In this study, the body length of the fossil catshark was estimated by comparing the teeth of present-day bullhead sharks with those of fossil sharks.
Based on the measurements, the largest tooth of a japanese bullhead shark from the "Naarai" Formation was estimated to be that of a 124.5 cm long shark. This size is the same as the largest of the present-day H. japonicus.

Fig. 1. The total length & the tooth size

Ref. 1. "Naarai" specimens

Ref. 2. Extant Heterodontus joponicus

Ref. 3.Tooth size measurements

For this measurement, five teeth were taken from the largest file of teeth on the right side of the upper jaw, their length and width were determined and averages were produced. Note that in H. japonicus females, total length 38 cm, only one tooth, R1, was used for this measurement.

Jul. 27, 2024