الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The beak varies in shape, size, length and function according to the type of diet consumed. The diversity in beak morphology led to confirmed the Darwin?s theory of evolution through natural selection (Trainor, 2003). The keratinized structure coating the beak plays a role in the protection the bones of the upper and lower jaws from injuries during searching and catching the preys. There are considerable variations in position and size of orbits due to the differences in the behavior and mode of locomotion of each species. Generally, the large sized avian orbits are equivalent to the characteristic large eyes of birds. Avian cranial kinesis is controlled by several bony elements and ligaments, which may constrain movement. At hatching, the skull is well formed miniature of that in the adult.