English: (A) Zhoukoudian Humerus III; (B) Zhoukoudian Humerus II; (C) Tianyuan (right); (D) Tianyuan (left); (E) Datong-1; (F) Datong-2; (G) Datong-3; (H) Datong-4; (I) Datong-5; (J) Datong-6; (K) Datong-7; (L) Datong-8; (M) Datong-9; (N) Datong-10; (O) Zhoukoudian Humerus III; (P) Zhoukoudian Humerus II. In the upper three rows, midshaft cross sections are illustrated for Zhoukoudian Humerus II and Humerus III, Tianyuan 1 right and left humeri, and Datong humeri (n = 10). The reconstructed cross section from the left humerus of Tianyuan 1 has missing cortical bone estimated in green. In the bottom row, cross sections are illustrated for a second, more distal location of Zhoukoudian Humerus II and Humerus III. Both estimated cross sections from the Weidenreich composite cast of Humerus II have been mirrored for illustration purposes