Skeletal indicators of locomotor behavior in living and extinct carnivores

Abstract

In this paper, I assess the correspondence between locomotor function (climbing, digging, and running) and skeletal morphology in living carnivores. Published behavioral observations are used to assign fifty-three extant carnivore species to four broad locomotor categories: arboreal, scansorial, terrestrial, and semi-fossorial. Body weight and measurements of claw shape, relative size of fore and hind claws, olecranon size and orientation, astragalar shape, and manus and hindlimb proportions are presented for each species. The correspondence between locomotor type and morphologic indices is examined with bivariate and multivariate (discriminant function) analyses. Results demonstrate that osteological indices are good predictors of locomotor behavior among extant carnivores. Arboreal and scansorial carnivores exhibit relatively more curved claws, longer proximal phalanges, and shorter metatarsals than do terrestrial taxa; semi-fossorial carnivores differ from other locomotor types in having relatively long olecranon processes, and longer fore claws than hind claws. Bivariate plots suggest that some characters, such as astragalar shape, reflect ancestry more than function. Applicability of the indices to other species is shown with a sample of eight non-carnivores and six Oligocene predators, including three sabertooth cats, a bear-dog, and two creodonts.