Morpho-functional analysis of the pelvis and hindlimb of Cyonasua (Carnivora, Procyonidae)

Abstract

The South American procyonid Cyonasua is a key taxon within the context of the Great American Biotic Interchange (GABI), offering valuable insights into the early dispersal of carnivorans into South America. This study presents a detailed morpho-functional analysis of the pelvis and hindlimb of Cyonasua. Bone elements of fossil specimens weredescribed and compared to those of extant South American procyonids, while functional indices were evaluated in the context of a broad ecological sample of carnivorans. Among extant South American procyonids, Cyonasua shares most morphological features with Procyon and Nasua. It appears well-adapted to a terrestrial lifestyle, with potential scansorial abilities and likely swimming capabilities, similar to Procyon. Additionally, the robustness and shorter hindlimbs of Cyonasua suggest an ability to resist bending and shearing stresses, likely supporting greater body weight and digging abilities, comparable to Nasua. Results further support similarities with scansorial and terrestrial generalist carnivorans, several of which possess digging abilities, such as Galictis, Meles, and Arctictis. The overall morphology of the pelvic limb of Cyonasua indicates remarkable locomotor versatility. This versatility, combined with its generalized forelimb morphology and its hypocarnivorous diet, likely enabled Cyonasua to exploit a variety of habitats and resources, potentially contributing to its success during the late Neogene in South America.