Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation

Area of Science:

• Comparative anatomy
• Functional morphology
• Bone biology

Background:

• Sciuromorpha exhibit diverse body sizes and locomotor behaviors, including climbing, gliding, and digging.
• Different lifestyles impose distinct loading patterns on sciuromorph bones.
• Trabecular bone structure adapts to habitual loading throughout an organism's lifetime.

Purpose of the Study:

• To investigate the effects of body size and lifestyle on trabecular bone structure in Sciuromorpha.
• To analyze how locomotor behaviors influence the femoral head's inner microstructure.

Main Methods:

• High-resolution computed tomography scans of the femoral head from 69 sciuromorph species.
• Classification of species into arboreal, aerial, fossorial, and semifossorial lifestyle categories.
• Analysis of trabecular architecture parameters within a standardized volume of interest in the femoral head.

Main Results:

• Positive allometry observed for bone surface density, bone volume fraction, and connectivity density.
• Negative allometry observed for degree of anisotropy, trabecular thickness, and trabecular separation.
• Specific trabecular parameters (connectivity density, bone surface density, trabecular thickness, trabecular separation) showed functional signals related to locomotor behavior, differentiating aerial from fossorial and arboreal from semifossorial species.

Conclusions:

• Femoral head trabecular architecture in Sciuromorpha is correlated with body mass and locomotor habits.
• Findings provide a foundation for further research into the functional significance of bone's inner microstructure.
• This study contributes to understanding non-primate lifestyle-related adaptations in trabecular bone.