In all living chordates, the physical structure of skeletal and musculature anatomy is testament to the evolutionary rule that form follows function. In a match of predator and prey, the Red-tailed Hawk and Eastern Cottontail Rabbit demonstrate their highly specialized function-determined forms. The hawk has developed highly acute eyesight, specialized talons and beak, and specializations for dexterous flight such as hollow bones. The cottontail has developed highly specialized hind-limbs with long muscles and tendons for quick ballistic jumping and the evasion of predators. Adaptations such as these are not planned innovations, but responses to evolutionary pressures.