A 15-year-old female skeleton is recovered from a disaster site in Mumbai. Forensic examination shows the first and second molars are fully erupted with moderate occlusal wear, but the third molars are unerupted. The medial epiphysis of the clavicle is unfused, and the distal femoral epiphysis shows partial fusion. What is the most appropriate next step to confirm skeletal maturity and refine the age estimate?