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The goal of this study is to explore the evolution of selachian (shark) teeth in the context of functional morphology. While asking how shark teeth work seems like a simple question with a simple answer (they cut, slice, tear, etc.), the issue is complicated by morphology. Sharks display a variety of tooth morphologies; presumably, different forms should have different functions. To quantitatively approach this issue, I subjecting shark teeth to performance testing on a variety of prey items to determine how teeth perform in puncture and tearing. This will be done using a MTS MiniBionixII universal testing system.

Teeth will also be modeled using finite element analysis (FEA) to look at the role morphology plays on the mechanical stability of the tooth. To the left is a 3D finite element model of a tiger shark tooth. I've placed a distributed load along the left side of the tooth, as would be expected during head shaking behaviour. The shading on the tooth represents different amounts of stress. Blue is low stress, green medium, and red is high stress.

When you apply the question of tooth function to fossil sharks, the problem becomes even more complex, as teeth are often the only part that fossilizes. Very little is known about diet or the rest of the feeding appartus in extinct species, unlike thier extant cousins. Paleontologists must reconstruct the entire life history and anatomy of a species based on little information. I am using a model based approach (FEA & RKEM) where I can look at the stress distributions within the tooth when different loads are applied, simulating different prey items. Data from all of the performance testing and morphological analyses will be combined into a final evolutionary analysis to look for patterns and correlated changes through evolution.

Species tested to date include: bull shark, lemon shark, Atlantic blacktip shark, great white, sandtiger, blue shark, caribbean reef shark, tiger shark, shortfin mako, porbeagle, great hammerhead, smooth hammerhead, bignose shark, sandbar shark, Ganges shark, and six-gilled shark.