["International Journal of Osteoarchaeology, EarlyView. ", "\nABSTRACT\nDistinguishing physiological from pathological bone formation in immature skeletal remains is one of the most persistent challenges in nonadult bioarchaeology, yet empirical criteria for this distinction are lacking in the literature. This study fills this gap by applying a descriptive, macroscopic baseline in a documented sample of 172 identified nonadult skeletons aged from five gestational months to 6 years, curated at the Granada osteological collection. After excluding taphonomically altered elements, 168 single scapulae and 166 ilia were analyzed under stereomicroscopy (7–40×) using standardized qualitative criteria to characterize surface morphology, anatomical distribution, and age‐related variation of extracortical bone deposits. The rate of ossification declines with aging, particularly after 0.5 years, although porosity may persist at vascular and muscular attachment sites. Physiological bone formation is characterized by flat spicules parallel to the cortex, moderately distributed extracortical pores with smooth, regular contours, centrifugal growth radiating from ossification centers, gradual cortical integration, and regions of reduced cortical thickness are spared. Conversely, the four individuals presenting systemic pathological skeletal involvement, despite the small sample, exhibited steeper spicule projection, dentate pore margins, disrupted centrifugal orientation, and premature ossification in regions that tendentially developed later. Some interindividual variability occurred within the physiological range, including retention of early‐stage traits beyond 1 year. These findings offer a morphological framework for interpreting periosteal modeling in early ontogeny, with implications for paleopathological assessment of nonadult remains. Future research incorporating larger samples—including more pathological cases, further validation, and geographically diverse collections is essential to initiate rigorous testing and refinement of these criteria.\n"]