Meeting Abstract
The advent of complex teeth in Mesozoic mammals permitted an increase in taxonomic and dietary diversity, enabling occupation of many different ecological niches. One complex tooth that arose during the Mesozoic, the tribosphenic molar, could simultaneously cut and crush food. The cutting portion of this tooth evolved first, and involved the movement of three cusps from a line into a triangle. This transition is exemplified by two insectivorous mammals, Morganucodon (linear) and Kuehneotherium (triangular). Here we test whether the difference in dental morphology between Morganucodon and Kuehneotherium are associated with differences in their ability to fracture insect prey. We gathered measurements from both species and made physical models of the molar tooth rows based on these measurements. We used the models to puncture a gel that mimicked insect cuticle and measured the energy and force required to fracture, maximum force and damage to the gel. Both models required a similar amount of energy to fracture the gel at roughly the same time, but the force at fracture imposed by the Kuehneotherium model was higher. The maximum forces produced by the models were similar, but it was reached later and required more energy for Morganucodon. Finally, the Kuehneotherium model produced more and longer fractures in the gel by distributing forces over a larger area. Taken together, the Kuehneotherium model was able to cause more damage to the gel more quickly than the Morganucodon model while expending less energy. These results demonstrate that changes in the molar morphology of early mammals had a profound effect on the biomechanics of food processing, and suggest that the evolution of increasingly efficient teeth was fundamental to their taxonomic and trophic diversification.
