Rostrum is a term used in anatomy for a number of phylogenetically unrelated structures in different groups of animals.
The rostrum (beak) of a grey heron
Crustacean: the rostrum of the shrimp Macrobrachium rosenbergii is serrated along both edges.
Insect: assassin bug piercing its prey with its rostrum
Cephalopod: the two-part beak of a giant squid
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone, however two parts are more prominent: the cranium and the mandible. In humans, these two parts are the neurocranium (braincase) and the viscerocranium that includes the mandible as its largest bone. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. In humans, these sensory structures are part of the facial skeleton.
Skull in situ
Anatomy of a flat bone – the periosteum of the neurocranium is known as the pericranium
Chimpanzee skull
Fish head parts, 1889, Fauna of British India, Sir Francis Day