(a) SEM–BSE image acquired at the periosteal area of the perissodactyl bone cross section. The inset denotes part of the area where the SEM–EDX maps were recorded. (b) SEM–BSE image and corresponding SEM–EDX elemental maps (bottom) recorded at approximately 1.2 mm from the periosteum. Fe (hydroxy)oxide precipitates fill Haversian canals (Fe,O maps). A small Mn contribution was detected in a Fe-rich precipitate (Mn map) while Si and Na form small precipitates near holes (Si,Na maps). Notation: FeOx, Fe (hydroxy)oxides; Si,Na, (Si,Na) mineral; CaP, apatite; CaCO3, calcite.