The shape of the mandibular corpus in large fissiped carnivores: allometry, function and phylogeny

Abstract

Mandibular corpus shape variability was investigated in seven families of both extant and extinct mammalian carnivores using two-dimensional landmarks and geometric morphometric methods.The landmark configuration represents the position of the fourth premolar relative to the canine and the lower carnassial, plus related features of the corpus profile.Between families, the corpus manifests differences in shape and allometry.Additionally, families differ in the relationship between the angle a (a carnassial trait proxy for hypo-hypercarnivory) and mandibular corpus shape.When phylogenetic relatedness is taken into account using five different phylogenies as covariates, interspecific scaling is still present but the relationship between a and corpus shape is no longer significant.This suggests that the allometric relationship reflects the physical constraints of mastication, resulting in relatively increased corpus depth with higher loads.In contrast, the angle a is related to corpus curvature and this relationship is phylogenetically constrained by the reduction of the molar battery in large feliforms early during the carnivore radiation.In summary, large fissiped carnivores show extensive functional convergence in mandibular corpus shape although the evolutionary routes leading to such functional convergence are different.