Femoral Shape in Procyonids (Carnivora, Procyonidae): Morphofunctional Implications, Size and Phylogenetic Signal

Abstract

Procyonids occur throughout the Americas and include ecologically diverse forms. They occupy diverse habitats and display a variety of locomotor modes and substrate preferences. Because of this ecological diversity, procyonids represent an interesting model for morphofunctional analysis of their postcranial skeleton. This work is an analysis of shape variation of the femur, a highly informative element of the appendicular skeleton of mammals, whose morphology reflects diverse locomotor abilities and is also related to body weight support and phylogeny. In this work, two femoral aspects were analyzed in all living procyonid genera within a wide comparative sample of carnivorans using 2D geometric morphometric techniques. Morphofunctional implications of the shape variations detected and relationships with locomotor modes and substrate preferences are discussed, as well as influence of body size and phylogeny. Analysis of the caudo-proximal shape indicated that procyonids present an intermediate morphology among carnivorans, but with some correlation with body size. In the analysis of distal femoral shape, procyonids were more separated among each other along Principal Component 1 and located on one extreme of the morphospace, while shape variation did not show association with body size. Even though the femoral shapes analyzed in the carnivoran sample showed significant phylogenetic signal, the latter was relatively low. In procyonids, the pattern of morphological variation of both femoral aspects does not agree with the phylogenetic structure. Therefore, most morphological variation found among procyonids can be related to known ecological characteristics of their locomotion or substrate preference and also partly explained by body size.