Influence of body size and locomotor behaviour on trabecular bone structure in the humeral and femoral heads of Muroidea

Abstract Trabecular bone is known to adapt to mechanical stimuli, but its adaptive signal is understudied in small mammals. Such studies could, for example, inform previous hypotheses about size-specific scaling patterns. Here we looked at muroid rodents to analyse the effect of body size and locomotor behaviour on the trabecular network of the proximal stylopodia. We used µCT scans of humeri and femora to quantify various trabecular parameters. We found that the trabecular network changes with size, characterised by positive allometric scaling of bone volume fraction, connectivity density, and specific bone surface and negative allometric scaling of trabecular thickness and spacing. When compared with the available literature on scaling within various mammalian taxa, our results add to growing evidence that scaling patterns differ between smaller and larger mammals. We detected no significant differences among locomotor groups, which may reflect the limited sample size. However, some descriptive patterns were apparent. Trends in the femur were more in line with the mammalian literature than those observed in the humerus, but more data is needed to confirm these patterns.