Identification
Teeth of C. hubbelli are morphological intermediates between C. hastalis and the extant species C. carcharias. They all possess erect triangular cusps, no nutrient groove, and a thin to no lingual dental band ("bourlette"). C. hubbelli exhibits transitional serrations which are finer/weaker than those of the extant species, and diminish in size apically.1 This feature may be confounded with the same pattern in nascent C. carcharias.2
C. hubbelli may be confused with C. subserratus (escheri), however they can be easily distinguished by their geographic distributions. C. hubbelli is exclusively found in the Pacific, while C. subserratus (escheri) is only found in the Northern Atlantic and Mediterranean.1
References
1. Ehret, D.J., Macfadden, B.J., Jones, D.S., DeVries, T.J., Foster, D.A. and Salas-Gismondi, R. (2012), Origin of the white shark Carcharodon (Lamniformes: Lamnidae) based on recalibration of the Upper Neogene Pisco Formation of Peru. Palaeontology, 55: 1139-1153. https://doi.org/10.1111/j.1475-4983.2012.01201.x
2. Hubbell G. (1996), Using tooth structure to determine the evolutionary history of the white shark. In: Klimley AP, Ainley DG, editors. Great White Sharks: The Biology of Carcharodon carcharias. San Diego: Academic Press. pp 9–18.