What is the importance of knowing cranium size, dentition, number of toes/fingers, flexibility of joints, locomotion styles, body size, the skeleton, etc. Of primates?

Important for identification.

Explanation:

Knowing the cranium size, dentition, number of toes/fingers, flexibility of joints, locomotion styles, body size, the skeleton, etc. of primates is very important to identify the specie of primates group. Different primates have different cranium size, dentition, fingers or toe's number, flexibility of joints, locomotion styles, body size, the skeleton etc so these information helps in identification and grouping of primates during classification.

not sure if this what   you'r looking for would be percent composition