Postcranial Skeleton of Glironia venusta (Didelphimorphia, Didelphidae, Caluromyinae): Description and Functional Morphology

Abstract

The postcranial skeleton of the neotropical living marsupial Glironia venusta is described and compared in a functional framework. Osteological and myological characters of 19 species of living didelphids and some additional placentals were consulted as models to explain functional implications from the morphology. The skeleton of G. venusta provides evidence about locomotory behavior and specific capacities of movements, and reveals patterns comparable to arboreal didelphids and placentals with high capacity to climb. In general terms, G. venusta has few diagnostic characters in the context of the didelphid sample analyzed, which includes representatives of all recognized clades in the family (second sacral not fused to the ilium, humeral greater trochanter well developed, tibia shorter than femur). Most of the postcranial pattern in G. venusta is consistent with arboreal locomotion, but unlike Caluromys and Caluromysiops, it seems to have faster locomotion. The morphology of the vertebral column, at the thoracic and lumbar portions, shows features that allow powerful lateral and sagittal movements during different phases of locomotion. The patterns evidenced in the forelimbs, pelvic girdle, and hindlimbs point to arboreal habits as well, except for some features on the humerus, illium and fibula. Even if most didelphids have been cataloged as generalized with respect to their mode of gait, the skeletal morphology of G. venusta and the high variation existent in further neotropical marsupials with a variety of body sizes, reveal a diverse combination of features associated to specialized capacities of movements. This indicates a diversity of locomotory modes and postures in didelphids.