Meeting Abstract
The convergent evolution of the talon, the distolingual extension of the tribosphenic upper molar, and additional features forming on the talon, such as the hypocone cusp, have been well documented across therian mammals. Exactly how the addition of this novel structure influences molar function is not completely understood. The present case study examines the crushing and shearing function of the talon within the dietarily diverse suborder Microchiroptera, in order to explore the adaptive implications of talon expansion in therian mammals. Crushing and shearing function was estimated using Relief Index (RFI), a measure of the degree of relief in the crown surface, attained from three-dimensional computer models of microcomputed tomography (microCT) scanned upper first molars. RFI of the entire molar was found to be sufficient in distinguishing dietary groups, including frugivores with low molar relief and a crushing-dominated molar function, and insectivores with high molar relief and a shearing-dominated molar function. However across dietary groups, the relief of the talon itself was consistently low, suggesting that it primarily performs a crushing function. The increased occlusal area dedicated to crushing provided by the expansion of the talon would be an adaptive benefit to a frugivorous microbat that relies on crushing for food breakdown. However, the adaptive benefit of a talon to other dietary groups, including insectivores that rely more heavily upon shearing for food breakdown, is not fully understood. Possible explanations are discussed.
