Meeting Abstract
Tetrapod limbs, especially joints, are necessarily linked to locomotion and a large amount of work has been done studying the connection between locomotor mode and bony morphology. Mammals occupy a wide variety of locomotor modes and mammalian tarsal morphology in particular has been shown to be highly correlated with locomotion. Here we examine astragalar morphology in caniforms to see which specific structures of the astragalus are linked to changes in locomotor mode and whether the astragalus changes in consistent ways from one locomotor mode to the next. We examine astragalar morphology using 3D geometric morphometrics (3DGM) of 140 specimens across 53 species including 42% of the diversity of the non-pinniped Caniformia. Previous studies on locomotor morphology in Carnivora have focused only on ecologically-diverse clades within the order (e.g., mustelids); this is the first study to incorporate 3DGM at a finer taxonomic scale, seeking to elucidate morphological disparity and macroevolutionary trends within the order rather than across it. Preliminary results using principal components analysis show that there is significant morphological diversity between locomotor groups with arboreal caniforms and terrestrial/cursorial caniforms, creating a spectrum of astragalar shape – arboreal taxa tended to have shallower trochleae and more articular surface on the astragalar head when compared to terrestrial or cursorial taxa. Future work will incorporate phylogenetic comparative methods to evaluate whether ecology, phylogeny, or a combination of the two are responsible for discriminating groups. These results also contribute to a larger body of work demonstrating correlations between ecology and morphology and have the potential to help distinguish locomotor modes in fossil caniforms.
