When moving in a variety of environments, quadrupedal mammals typically exhibit a form of lateral gait sequence, where the movement of a hind-limb is coupled with the movement of the fore-limb on the same side of the body (Lemelin, et. al: 2003). In contrast, all quadrupedal primates, with varying degrees of success, are able to move throughout their environment using a diagonal sequence gait (Lemelin, et. al: 2003; Schmidt: 2005; Schmidt, et. al: 2006). Here, locomotion is marked by the simultaneous motion of adverse fore-limb reaching and hind-limb pushing (Schmidt: 2005; Schmidt, et. al: 2006) (see Appendix V). In order for this particular gait sequence to be effective in a number of environments, both terrestrial and arboreal quadrupedal primates require the ability to generate sufficient power in the hind-limbs that pushes the body forward, while maintaining over-all stability. Moreover, to create the fore-limb motion associated with a …show more content…
It should be noted that this generalization of primate posture applies to arboreal species, excluding squirrel monkeys. Rather, like rhesus macaques, squirrel monkeys exhibit signs of an increasingly vertical stance compared to other arboreal primates (Schmidt: 2005; Whitehead and Larson: 1994). Subsequently, the movement of squirrel monkeys resembles that of rhesus macaques, insofar as humeral retraction and hind-limb pushing characterizes both species (Cheng and Scott: 2000; Lemelin, et. al: 2003; Schmidt: 2005). In turn, while both species primarily move in distinct environments (Cawthorn: 2006; Cawthorn: 2011; Nakatsukasa: 1994), the morphological response to that difference will be tempered by the relative similarity in limb posture that has been observed in previous investigations (Schmidt: 2005;