Human baby, anatomical artwork. This artwork shows the baby's skeleton. The skeleton of a baby is not fully developed at birth. The clearest example of this is the bony plates of the cranium (the upper part of the skull). These encase the brain, and are not fully fused at birth. As the baby grows and develops, the plates fuse along lines known as sutures. Ossification of the bones continues in childhood and adolescence, and a supply of calcium is needed in the diet to ensure healthy bone development. Bones shown here include the spinal bones, the ribcage, the arm and finger bones, the pelvis, the jaw bones, the facial bones and the cranium.