Modes of Primate Locomotion
• Locomotion refers to how a primate gets around.
• A mode of locomotion, as used here, refers to how a primate most frequently moves around.
• Many primates employ multiple modes of locomotion.
• A mode of locomotion generates selective forces which change the body.
Quadrupedalism
• Quadrupedalism does not simply mean that a primate moves with hands and feet touching the ground.
• It assumes two distinctive forms: arboreal quadrupedalism and terrestrial quadrupedalism.
Arboreal Quadrupedalism
Examples: Langurs, Howler Monkeys,
Guenons.
Occipital condyle/formen magnum is located in the rear of the skull
Cranial vault is low but cranium is long
Bones of the pelvis are long and narrow
Shoulder harness is located below the spine
vertebrae are not markedly different in size
Chest is narrow
Hindlimbs and forelimbs are equivalent in size and length
Terrestrial Quadrupedalism
Vertical Leaping
Lengthened and fused tarsal bones
Hind limbs are much longer than forelimbs
Feet much larger and longer than hands
Knuckle WalkingGorilla
BrachiationRib cage is broader than that of quadrupeds.
Spine of some brachiators has one fewer vertebra than quadrupeds
Neck has one more cervical vertebra over quadrupeds
Quadrumanous/Quadrumanual
Essentially, the anatomy is analogous to that of a brachiator, but the adult Organutan is too large to brachiate.
Male Orangutans in particular get so large that they have to clamber to the ground and move to the next tree by fist walking.