A Simple Morphological Predictor of Bite Force in Rodents

Bite force was quantified for 13 species of North American rodents using a piezo-resistive sensor. Most of the species measured (11) formed a tight relationship between body mass and bite force (log 10(bite force) = 0.43(log 10(body mass)) + 0.416; R2 \u3e 0.98). This high correlation exists despite the ecological (omnivores, grazers and more carnivorous) and taxonomic (Cricetidae, Heteromyidae, Sciuridae and Zapodidae) diversity of species. Two additional species, Geomys bursarius (Geomyidae) and a Sciurus niger (Sciuridae), bit much harder for their size. We found a simple index of strength based on two measurements of the incisor at the level of the alveolus (Zi = ((anterior-posterior length)2 × (medial-lateral width))/6) that is highly predictive of bite force in these rodents (R2 \u3e 0.96). Zi may be useful for prediction of bite force (log10 (Bite Force) = 0.566 log10 (Zi) + 1.432) when direct measurements are not available