Final answer:
The evolutionary change that occurred in the animal skeletal system as animals moved from water to land was the restructuring of the limb placement underneath the body for more efficient movement and reduced energy expenditure.
Step-by-step explanation:
The transition of animals from water to land involved significant changes in body design for locomotion. One major evolutionary adaptation was the placement of limbs under the body, reducing the need for large adductor muscles and leading to a more efficient stride. This adaptation involved the rotation of the femur and humerus to point the ends of the limbs and digits forward.
This reconfiguration allowed for forward motion rather than an upward and forward motion, creating a stride similar to that of a pendulum. The appendicular skeleton of land animals, such as the shoulders attaching to the pectoral girdle through muscles and connective tissue, also facilitated locomotion on land by reducing the jarring of the skull during movement.