     the skull is a bony structure in the head of most vertebrates (in particular, craniates) that supports the structures of the face and forms a protective cavity for the brain. the skull is composed of two parts: the cranium and the mandible. the skull forms the anterior most portion of the skeleton and is a product of encephalization, housing the brain, many sensory structures (eyes, ears, nasal cavity), and the feeding system. functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to help the brain use auditory cues to judge direction and distance of sounds. in some animals, the skull also has a defensive function (e.g. horned ungulates); the frontal bone is where horns are mounted. the english word "skull" is probably derived from old norse "skalli" meaning bald, while the latin word cranium comes from the greek root ÎºÏÎ±Î½Î¯Î¿Î½ (kranion). the skull is made of a number of fused flat bones. == fish skull == thumb|right|fish head parts, 1889, fauna of british india, sir francis day the skull of fishes is formed from a series of only loosely connected bones. lampreys and sharks only possess a cartilaginous endocranium, with both the upper and lower jaws being separate elements. bony fishes have additional dermal bone, forming a more or less coherent skull roof in lungfish and holost fish. the lower jaw defines a chin. the simpler structure is found in jawless fish, in which the cranium is normally represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. distinctively, these fish have no jaws. cartilaginous fish, such as sharks and rays, have also simple, and presumably primitive, skull structures. the cranium is a single structure forming a case around the brain, enclosing the lower surface and the sides, but always at least partially open at the top as a large fontanelle. the most anterior part of the cranium includes a forward plate of cartilage, the rostrum, and capsules to enclose the olfactory organs. behind these are the orbits, and then an additional pair of capsules enclosing the structure of the inner ear. finally, the skull tapers towards the rear, where the foramen magnum lies immediately above a single condyle, articulating 
Flat_bones Skull Vertebrate_anatomy