Size and positioning of the teeth and infratemporal fossa relative to taxonomic and dietary variation in primates

Abstract

The infratemporal fossa grows allomorphically in primates at a faster rate than general cranial and inferred body size. The coefficient of allometry approximates 1.5 across most primate groups, suggesting direct scaling of the musculus temporalis cross-sectional area to body mass. This coefficient is larger than 1.5 in Lorisoidea and Ceboidea. Medio-lateral relative growth of the infratemporal passage that accommodates m. temporalis rather than antero-posterior growth absorbs a disproportionate amount of this expansion. Likewise, infratemporal fossa breatdh is positively allometric to tooth size, especially in insectivorous, frugivorous and folivorous primate samples that are homogeneous with respect to diet. The seemingly growth-related positive relation between tooth size and distal placement of the zygomatic root that is consistent over the cumulative sample is erased by controlling for diet. Increased relative amounts of m. temporalis per unit of dental occlusal area is indicated in larger-bodied forms; increasing crown height may be a mechanism to adjust for this.