Fig. 3
From: Identifying the homology of the short human pisiform and its lost ossification center
Comparison of pisiform and calcaneus ossification patterns in humans, chimpanzees, and macaques. All calcanei and non-human pisiforms progress through the same ossification stages: primary, unfused, partially fused, and fully fused. Human pisiforms develop from a single ossification center. Fully cartilaginous pisiforms were identified in some species, including humans and chimpanzees (arrowheads), but not macaques. Palmar is up, dorsal is down. Scale bars = 1 cm