Quantitative muscle architecture in large carnivorous marsupials (Marsupialia: Dasyuridae) and links to substrate use and prey processing

The Dasyurid species Sarcophilus harrisii, Dasyurus maculatus, and Dasyurus viverrinus, occupying diverse ecological niches and forming a guild structure in Tasmania, provide a basis for examining the roles of various forelimb muscle groups in prey capture and locomotion. Muscle fiber architecture is a key contributor to muscle force and can indicate specialized, repeated forelimb engagement. We performed wet dissections and virtual dissections via computed tomography to provide the first modern descriptions for the three species. We also quantified intrinsic forelimb muscles and compared normalized physiological cross-sectional area (PCSA) across species for individual and grouped muscles. The topology and muscle PCSAs are similar across species with select functional groups showing slight deviations. Overall proportions and ratios between antagonistic muscle groups reveal that D. viverrinus shows an overall reduction in muscle PCSA, whereas S. harrisii and D. maculatus appear to show an emphasis on muscle groups engaging in specialized behaviors for prey processing and arboreal locomotion, respectively. The results support the known trend of conserved forelimb musculature in marsupials. Nevertheless, muscle PCSA remains an important biomechanical indicator for specialized forelimb use in dasyurids.