Scanning electron microscopy BSE (A, B, G) and SRXTM (C–F) histological sections of Pteraspis sp. NRM‐PAL C.5943, structure of the cephalothoracic shield of Pteraspis (A); detail of the superficial layer and L1 of the same specimen (B); NRM‐PAL C.5944, section through the pineal plate (C); volume rendered virtual thin section of the tubercles, showing the canaliculi radiating from central pulp canals and ramifying at the enameloid/dentine junction, specimen lost during sampling (D); NRM‐PAL C.5945, volume rendered virtual thin section showing histological structure of the body scales (E); transverse volume rendered virtual thin section through L2, showing thread‐like spaces pervading the entire thickness of the radial walls, specimen lost during sampling (F); NRM‐PAL C.5943, section through L3 and the base of L2 (G). Pin., pineal window. Scale bar equals 373 μm in (A), 177 μm in (B), 339 μm in (C), 61 μm in (D), 149 μm in (E), 86 μm in (F) and 123 μm in (G).