Meeting Abstract
The scaling of morphology has been investigated for over a century. However, only a few studies have considered that the scaling effect might depend on the loading regime determined by the locomotor behavior of an animal. The sciuromorph rodents constitute an insightful object to investigate how the interplay of body mass and locomotion affects the postcranial morphology. Thy can be categorized into arboreal, fossorial, and aerial locomotor groups, each including a body mass range spanning two or three orders of magnitude. We analyzed univariate and multivariate (shape) femoral parameters for 139 out of approx. 300 species. PGLS regressions were used to test whether intercepts and slopes differ relative to body mass for the derived fossorial and aerial groups when compared to the ancestral arboreal one and whether all slopes differ from isometry. Most of the univariate parameters scaled with isometry, suggesting that scaling adjustments have not played a significant role for most of the femoral features. The sizes of the femoral head and condyles, the width of the patellar groove and the in-levers of the muscles attaching to the major and lesser trochanters displayed a lower scaling exponent in fossorial when compared to arboreal species. The shape of the lesser trochanter exhibited differences in scaling among locomotor groups, manifested in the orientation and protrusion from the shaft. We suggest that these femoral features had a functional significance during the ecological diversification of sciuromorph rodents.
