Poster presentation 12th International Mammalogical Congress

Morphological variation of epipubic bones in didelphid marsupials: Sexual dimorphism and locomotion. (#671)

Gabby Guilhon 1 , Caryne Braga 2 , Rui Cerqueira 2
  1. Vertebrates Department, National Museum of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
  2. Ecology Department, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil

The study of skeleton morphology using linear morphometry allows us to assess the influence of size and shape in bone functions. Marsupials are one of the main vertebrate groups that possess epipubic bones. There are two hypotheses for its function; reproduction and locomotion. The aim of this work was to study the morphological variation of these bones to understand its function in Neotropical marsupials. We measured 371 skeletons (epipubic bones, pelvis, humerus, femur and tibia) of males and females of six genera and nine species with different locomotion habits to test the sexual dimorphism and its locomotion influence. We named structures of the epipubic bone that were undefined until now. We demonstrated the sexual dimorphism in size through t-tests and morphological dimorphism through qualitative osteological analysis. Females had longer and more curved epipubic bones than males in all studied species. Furthermore, a principal pomponent analysis (PCA) of epipubic bone and pelvis measurements generated groups consistent with the locomotion habits (semi-aquatic, arboreal, scansorial and cursorial), and the most important measures were the longest length and the base width of the epipubic and the pubis length, where the epipubic articulates. This differentiation in locomotion habits also occurred when we applied a PCA on the appendicular skeleton measurements, in which the more important variable was the humerus. These results support both previous hypothesis: 1) reproduction function - with a longer bone, females can have more muscle attached to support the abdomen; 2) locomotion function – specialised morphological features for each locomotor habit.