Meeting Abstract
Natural animal propulsors show high levels of energetic efficiency in their movements which man-made propulsors have not yet been able to adequately replicate. The analysis of bending patterns of terrestrial animals could provide insight into the construction of man-made propulsors. This study was modeled after a previous paper by Lucas et al. (2014), which showed that during swimming and flight, regardless of medium and phylogeny, all examined animals moved their propulsors in a similar manner using predictable, characteristic motions. Whether similar sets of rules apply during terrestrial locomotion remains unknown. Using 88 videos representing 50 vertebrate species obtained from open source platforms and contributed research videos, we quantified bending during propulsion by calculating a maximum flexion angle (FA) and flexion ratio (FR) in terrestrial vertebrates. Maximum flexion angle is defined as the minimum acute angle made by the vertex around which bending centered. Flexion ratio was calculated as the ratio of the distal segment relative to the total propulsor length, as centered about the vertex. Phylogenetic generalized least squares analyses illustrated significant but low K values for both flexion metrics (FA: K=0.161, p=0.001, FR: K=0.289, p=0.001), implying a weak evolutionary basis to the observed patterns, and that they instead are driven by other factors, such as foot posture, environment, and gait. Phylogenetic ANOVAs showed that locomotor foot posture (i.e., plantigrade, digitigrade, and unguligrade) had no statistical effect on maximum flexion angle (F=2.14, p=0.13) or flexion ratio (F=3.19, p=0.05). These results suggest that as for flight and swimming, terrestrial locomotion is also constrained by a set of constrained bending rules.
