Increasing evidence suggests that conditions in early life have important consequences for ultimate body size and fitness. Skeletal parts are often used as retrospective indices of body size and growth constraints because of their resistance to seasonal variation in resource availability. Yet, slow-maturing bones are poor predictors of resource limitations during early development, as later benign conditions may lead to compensatory growth. We analysed the temporal growth dynamics of different sections of the lower jaw of roe deer Capreolus capreolus and found that the medioanterior section of the lower jaw reaches 95% of asymptotic size already at 2–4 months post partum, whereas the posterior section reaches 95% of asymptotic size at 14–16 months post partum. Hence, the size of the medioanterior section of the lower jaw is only dependent on resource availability in utero and the first few months post partum and, as such, potentially leaves a fingerprint of prenatal growth conditions that is evident even in adult individuals. This supports earlier findings in ungulates of a shift in skeletal growth spurts after weaning, and suggests that the choice of skeletal index for population and cohort studies is not trivial.