| Sharks of the genus Squalus from the Oligocene to Holocene in various localities in Japan are summarized. The original total lengths of the sharks were calculated from the fossil teeth of these sharks. Estimates of total length from fossil sharks were based on data obtained from the extant Squalus mitsukurii. There are three inaccuracies in this estimation: 1. there are many species of dogfish sharks, and it is not known if they show the same relationship between body length and tooth size as that of Squalus mitsukurii ;2. the data obtained for Squalus mitsukurii are from a small number of individuals; and 3. The relationship between body length and tooth size is based on data from the fifth lower tooth of the shark (s. mitsukurii), and the estimated body length from these data is minimal. Despite some problems, it is meaningful to estimate the total length of a shark from its fossil teeth. |
| Pleistocene |
| 20240130F |
| Pliocene |
| 20231221 |
| Miocene |
Sharks of the genus Squalus with serrations
as known as Squalus occidentalis (AGASSIZ, 1856)/ Squalus serriculus JORDAN & HANNIBAL, 1923
| a, b; Kamimitsugano Facies, c; Kitanagano Facies |
| Oligocene |
| 20240212, 20231128, 20150101, 20081113 |
| Cretaceous |
| 20240210 |
Squalus with weak serrations
| Cretaceous |
| 20130128 |
| The relationship between the tooth size and total body length in the dogfish shark Squalus mitsukurii (Jordan & Snider, 1903) |
| Otokawa Formation: 8.4 - 6.2 Ma Nakajima, T., Iwano, H., Danhara, T., Yamashita, T., Yanagisawa, Y., Tanimura, Y., Watanabe, M., Sawaki, T., Nakanishi, S., Mitsuishi, H., Yamashina, O. and Imahori, S. (2019) Revised Cenozoic chronostratigraphy and tectonics in the Yatsuo Area, Toyama Prefecture, central Japan. Jour. Geol. Soc. Japan, 125(7), p.483?516. Nagamori, H. and Watanabe, M. (2023) Stratigraphic correlation of the Higashibessho, Tenguyama and Otokawa formations in the central to eastern area of Toyama Prefecture, central Japan. Bull. Geol. Surv. Japan, vol. 74 (3), p.119?131. |
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