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.