Journal of the
Ocean Science Foundation

An open-access free online peer-reviewed Marine Biology Journal, since 2008.

published by the Ocean Science Foundation
 
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click on covers for COVER PAGE images
 

 

RESEARCH ARTICLE

Dental variations in the crocodile shark, Pseudocarcharias kamoharai (Lamniformes: Pseudocarchariidae): implications for fossil Pseudocarcharias

Kaelin A.R. Reichmann, Maya G. Mahoney, Douglas J. Long & Kenshu Shimada

The crocodile shark, Pseudocarcharias kamoharai (Matsubara), is an extant lamniform shark. Whereas the genus is represented in the fossil record by isolated teeth found primarily in Miocene deposits nearly worldwide, many biological aspects, even for the extant Pseudocarcharias, are still poorly understood, including the ontogenetic development of teeth. In this study, we used linear regression analyses to examine the relationship between the total body length (TL) and tooth crown height (CH) or enameloid height of each tooth in 14 individuals of extant P. kamoharai collected from the Pacific and Indian Oceans. The resulting regression equations suggest that the increase in CH of teeth through replacement is generally proportional to an increase in TL, with high predictability of TL from CH (p less than 0.0001) found in teeth located mesially (the so-called 'anterior teeth'). In addition, we used two-sample t-tests to investigate sexual and geographic dimorphism in standardized crown height and crown acuteness of each tooth. Whereas no significant dimorphism was found between the two primary collection localities, the lower first anterior tooth was found to be significantly taller in males than females. This study allows TL estimations for Pseudocarcharias in the fossil record. If our regression equations for the anterior teeth are applied to previously described anterior teeth of Pseudocarcharias from the Miocene with preserved crowns, their TL estimates range up to 231 cm. This uppermost estimate is intriguing because it is about twice the size of the largest known extant Pseudocarcharias, providing new insights into the Neogene marine ecosystem.

 
 
 

CITATION:

Reichmann, K.A.R., Mahoney, M.G., Long, D.J. & Shimada, K. (2025) Dental variations in the crocodile shark, Pseudocarcharias kamoharai (Lamniformes: Pseudocarchariidae): implications for fossil Pseudocarcharias. Journal of the Ocean Science Foundation, 45, 36-47.

https://doi.org/10.5281/zenodo.18049121

publication date: 29 December 2025