In addition to overall size and shape, there are other variances in skulls. The nasal spine, a bony projection at the base of the aperture, might indicate whether a nose hooked down or turned up. The next stage is one of my specialties, craniometric analysis, which is the study of skull measurements. You put about 80 measurements into a computer to get an analytical model that best fits one of the main population groups. Subtle deformations of bone can even hint at an adult's occupation, as constant use of a certain muscle will literally pull the bone it is attached to, misshaping it slightly and creating, for example, a heel spur.
Children grow at different rates, with spurts at various times.
At 4 to 6 years they have big heads because the brain case is larger than the face. Then around the third grade, the face starts growing and pretty soon a kid has a bigger face. Teeth are also a major clue to age, he said. In the first grade kids lose their front baby teeth, and their permanent ones begin coming in. The teeth of Hispanics tend to grow in four to six months sooner than those of whites.