Human Anatomy - Kotsan I. Y. 2009

Skeleton of the Head
Some data on the phylogeny of the skull

The Skull of lower Chordates and their ancestral forms evolved in connection with The Emergence of the Mouth opening as the initial section of the Digestive System, The Development of the branchial respiratory apparatus, and the early Formation of the Brain.

During the further evolution of chordates, the skull gradually became a receptacle for the increasingly complex brain and the separating Sense Organs.

The formation of The Skull and its regions in mammals is characterized by: progressive ossification of cartilaginous elements; strengthening of The connection between the neurocranium and splanchnocranium, with a downward shift of the visceral skull relative to the braincase driven by the significant Development of the brain, which is most pronounced in primates; a reduction in the number of bones As a result of reduction or fusion; the formation of the zygomatic arch; closure of the outer wall of the Orbit in primates and some other mammals; the emergence of auditory ossicles from the proximal sections of the First and Second branchial arches; differentiation and reduction of the number of Teeth; and, finally, complete fusion of the incisive bone with the maxillae (in primates only).