Meeting Abstract
Feet mediate animal-substrate interactions across an animal’s entire range of limb poses used in life. Despite its importance, the foot is typically either ignored or treated as a “black box”—an anatomically complex set of visually obscured components that are difficult to simulate. The most dominant skeletal elements are the metatarsals, the ‘bones of the sole.’ In plantigrade animals, intermetatarsal mobility offers the potential for active reconfiguration within the foot itself. Using marker-based XROMM, we measured metatarsal kinematics in three juvenile American alligators (Alligator mississippiensis) across their locomotor and maneuvering repertoire on flat surfaces. Alligators are capable of postural extremes—from a belly sprawl to a high walk—and the foot is flexible enough to accommodate these diverse poses. Initial results reveal: 1) Regardless of limb placement, the metatarsals conform to the ground to maintain fully plantigrade contact throughout most of stance. Coordinated intermetatarsal motion adapts foot shape based on phase, spreading in stance up to 200% of the most compressed configuration during swing. 2) Intermetatarsal mobility contributes significantly to everted and inverted foot poses. Alligators predominantly inverted the pes; up to 40 degrees of inversion-eversion was measured, whereas only 10 degrees of ab-adduction was found. Continuing work will put intermetatarsal mobility in context of crural, pelvic, and digital kinematics, with the aim to understand the inner workings of the pedal “black box” and how it contributes to animal locomotion.
