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Keywords:

  • Vervets;
  • Gait transitions;
  • Interlimb coordination;
  • Back motion;
  • Stride length

Abstract

Cine film documenting unrestrained locomotion of vervet monkeys (Cercopithecus aethiops) ranging in age from 6 to greater than 48 months was analyzed to provide information on gait transitions from walking to loping. Changes in the duration of time between reciprocal footfalls were measured to determine how alternate limb movements, which occurred during walking, were converted to synchronous limb coordination characteristic of loping. Footfall pattern changes were also determined, and walk-lope transition speeds were plotted on logarithmic coordinates, as a function of body mass.

Conversion from alternate to synchronous limb movement during vervet walk-lope transitions was effected by systematic decreases in the duration of time between successive footfalls. These decreases primarily affected contralateral limb pairs, RH-LH and RF-LF. Synchronous contralateral limb movement was considered to be mechanically advantageous because, when coupled with increased ranges of back motion, it provided a mechanism for increasing hindlimb step length.

Intraspecific scaling of walk-lope transition speed in vervets provided support for McMahon's (1975) elastic similarity principle.