Forelimb and hindlimb loading patterns during quadrupedal locomotion in the large flying fox (Pteropus vampyrus) and common vampire bat (Desmodus rotundus)

摘要

Adaptations for flight have greatly modified the forelimbs and hindlimbs of bats compared to other mammals so that terrestrial and/or above branch quadrupedal locomotion is awkward and unusual for most species. However, suspensory quadrupedal gaits are quite common for bats, but little is known about this type of movement and no data are available on how these animals load their limbs and support the body. Values for vertical, fore-aft and mediolateral peak forces were collected for the forelimb and hindlimb during suspensory quadrupedal locomotion in the large flying fox (Pteropus vampyrus) and common vampire bat (Desmodus rotundus), and during terrestrial locomotion in the common vampire bats. During suspensory quadrupedal locomotion in both species, the hindlimbs serves as the primary weight-bearing and braking organ, whereas the forelimb has a reduced weight-bearing role and acts as the primary propulsive limb. Mediolateral forces are dominated by medially directed forces by the animal that likely serve to help maintain grip' while moving below supports. Kinetic patterns of terrestrial locomotion in the common vampire bat are completely opposite, and resemble data that has been reported for most mammals with the exception of relatively high lateral forces. The data presented here add to the growing body of knowledge that suspensory quadrupedal locomotion does not represent a neuromuscular mirror to non-suspensory quadrupedal gaits. Furthermore, this study demonstrates that suspensory quadrupedal gaits are not the same across mammals, and species have adopted multiple mechanical strategies for moving quadrupedally below a support.