Extended Data Fig. 6: Weaning transition recorded in the postcranial bones of NMMNH P-27844.

(a) Transverse section of right humerus diaphysis under cross-polarized light, showing arrangement of tissues and large medullary cavity and location of close-up image. (b) Close-up of cortex of right humerus under cross-polarized light, showing increase in proportion of parallel-fibered bone (brighter tissues) later in growth (arrow), indicative of a decrease in growth rate. (c) Transverse section of right tibia diaphysis under plane polarized light, showing location of close-up image. (d) Close-up of cortex of right tibia under cross-polarized light with a lambda filter, showing transition (arrow) from highly-vascularized fibrolamellar bone with a high proportion of woven-fibered matrix (upper right) to more slowly-growing parallel-fibered bone with reduced vascularity (lower left). (e) Transverse section of right radius diaphysis under cross-polarized light, showing location of close-up image. (f) Close-up image of cortex of right radius under cross-polarized light with a lambda filter, showing annulus of parallel-fibered bone (arrow) separating region of highly-vascularized fibrolamellar bone (lower right) from region of less-vascularized fibrolamellar bone with a higher proportion of parallel-fibered bone (upper left). Scale bars: 1 mm (a, c, e), 500 µm (b, d, f).