Extended Data Fig. 4: Changes in zinc associated with birth in the deciduous upper premolars of NMMNH P-27844.

Postnatal dentine is enriched in Zn in the deciduous upper ultimate premolar (a, b) and the deciduous upper second premolar (c, d). (a) Overview of thin section showing location of close-up image. (b) Mosaic image showing protocone in cross-polarized light, with trace element map overlain, showing change at histologically-inferred neonatal line (dashed line; NNL). (c) Overview image of embedded block showing location of trace element map. (d) Trace element map showing increased postnatal Zn. Scale bars: 1 mm (a, c), 500 µm (b, d). Abbreviations: NNL, neonatal line.