In mammals, nails, claws, and hair are composed of keratin. The lightweight bill is far more conducive to flight than a heavy jaw full of teeth. The sharp cutting edges and strength of a beak are highly effective for killing, tearing flesh, and crushing bone. The design is magnificent evolutionary engineering. Cranial kinesis and the mandibular notch are two fine morphological modifications.
Cranial kinesis describes the mobility of the maxilla or upper jaw.
The maxilla is not locked in place. The mechanics of the maxilla allow it to slide forward and backward thus enabling the beak to open even wider. The mandibular notch, especially pronounced falcons, is a feature in raptor beaks that aids in killing prey. It is a sharp notch in the beak that can be slid between a victim's vertebrae to sever the spinal cord. Talons are impressive claw-like features used to capture, hold, and kill prey.