Final answer:
Skulls can be classified according to their biological features into anapsid, synapsid, and diapsid, based on the presence and number of temporal fenestrae. Human skulls, specifically, are part of the axial skeleton and develop via intramembranous ossification, with fontanelles accommodating brain growth in infants.
Step-by-step explanation:
Classification of Skulls Based on Biological Background
Skulls can be classified biologically in various ways. An important method is by examining the fenestration pattern, which relates to the number and arrangement of temporal fenestrae, openings in the skulls of reptiles and other vertebrates. This classification identifies three types of skulls: anapsid, synapsid, and diapsid. Anapsid skulls have no temporal fenestrae and are seen in early fossil reptiles. Synapsid skulls have one opening behind each eye socket and are found in mammals, including humans. Diapsid skulls possess two openings behind each eye socket, commonly found in birds and reptiles. Another way to classify skulls, particularly in humans, involves analysis of cranial features such as shape and size, which have historically been misused to establish biased racial hierarchies. Current understanding rejects these discriminatory practices as all human races have skulls with identical biological capabilities. The study of skulls also encompasses examination of the axial and facial bones. The axial skeleton is part of the broader human skeletal structure, which includes the cranial cavity that houses and protects the brain. The cranial bones develop through intramembranous ossification from mesenchyme. During embryonic development, large areas of connective tissue known as fontanelles - the soft spots on an infant's head - allow the skull to change shape during childbirth and accommodate brain growth post-birth. The architecture of the internal cranial cavity is further described by the subdivision into three cranial fossae.