Answer:
C. Bone fusion
B. Skull sutures
Step-by-step explanation:
When lacking information about the age of a specimen, you can apply different techniques using the skeleton to find out the approximate age of the individual.
Usually, teeth are useful in determining the age of the specimens. But in some species, age determination through these structures is not easy. It requires laboratory elements and a high degree of precision.
Another way to determine the age of an individual is by analyzing the fusion degree of different bones.
Let us think about the skull of an animal or a person. It is composed of many bones that fit all together in a perfect way. Each bone is closely related to the adjacent ones and is usually involved in the same functions -feeding, breathing, hearing, among others-. The limits between these bones are the suture lines.
In the early post-natal stages, these bones are free. They fit all together, but they are not fused. But with time, they begin a fusion process that completes in adulthood. This fusion process occurs in the sutures.
As a general pattern, groups of bones with the same function get fused at the same time. Each group develops and fuses in a particular chronological sequence and is related to the adaptation to the environment and the biological habits.
The degree of fusion of the suture is a reliable indicator to differentiate age stages.