EVERYDAY SCIENCE

Detailed explanation-1: -The limbs had evolved from fins; during the transition, our back-boned ancestors lost rows of rigid fibers, called actinotrichia, that provide structural support and guide fin development. The number of digits was also later winnowed to a maximum of five on each limb.

Detailed explanation-2: -Mammals may have limbs that are specialized for a particular way of moving. They may be specialized for running, jumping, climbing, flying, or swimming. Mammals with these different modes of locomotion are pictured in Figure below. Mammalian Locomotion.

Detailed explanation-3: -Most mammals have four limbs, but these “arms” and “legs” come in many shapes and sizes, and the appendages (their “hands” and “feet”) can be paws, claws or hooves. The exact form these limbs and appendages have depends on the specific needs and habits of the individual species.

Detailed explanation-4: -Mammalian limbs are positioned parasagitally under the body, with the elbow rotated posteriorly and the knee rotated anteriorly. The number of elements in the pectoral girdle is reduced, and the scapula is often highly mobile. The ilium of the pelvis is reoriented anteriorly.