A PATHOLOGIC AND DEFORMED SQUALICORAX PRISTODONTUS TOOTH FROM THE LATEST MAASTRICHTIAN BASAL HORNERSTOWN FORMATION, GLOUCESTER COUNTY, NEW JERSEY, USA

A Squalicorax pristodontus tooth (NJSM 22369) from the latest Maastrichtian basal Hornerstown Formation in Gloucester County, New Jersey exhibits atypical, pathologic features. Located centrally on the crown’s lingual surface, a patch of thickened enamel features a series of sub-vertically oriented (in the final occlusal position), sub-parallel, enamel ridges. Additionally, the distal carina is deformed, exhibiting a small protrusion which does not affect the serrations. Considering the rarity of pathologic features on modern shark teeth, it can be assumed that both the enameloid protuberance and the deformed carina resulted from the same mechanism.

Abnormal dentition among modern chondrichthyans is generally attributed to feeding-related injury to the jaw cartilage and/or gum tissues. Batoid tail spines and teleost fin spines, as well as fishing hooks, are known to puncture tooth-forming tissues in sharks, resulting in pathologic teeth. Typically, these pathologies take the form of twisted or bent crowns and roots, abnormal tooth growths, or deformed tooth files. Although it is nearly impossible to determine the cause of dental abnormalities in fossil shark dentition, ancient pathologic teeth typically exhibit very similar features, suggesting that the causative mechanisms are similar.

Pathologic shark teeth are unusual, generally accounting for far less than 1% of both modern and fossil specimens. However, this proportion is highly variable among species, which is likely the result of variations in prey preference, predation strategies, and jaw anatomy.