Right oblique view of the spine reconstructed from low-resolution data (7.46 μm).

(A) Shows the approximate location of the area of interest examined at high-resolution (0.678 μm). Scale bar is 1500 μm. (B) Virtual thin section of the spine, showing its overall histological organization, with generations of odontodes highlighted in different shades of pink. Yellow arrows indicate the presence of poorly mineralized bone. Blue is bone with many vascular canals, green is bone with few vascular canals, and red is the outer layer of dentine ornamentation. Scale bar is 300 μm. (C) Closer view of an odontode. Scale bar is 70 μm. (D1-D3) 3D reconstruction of odontode morphology, showing relative distribution of odontodes in three generations (go1, pink; g0 2. dark purple; go3, light purple). Scale bar is 300 μm. Abbreviations are: cc, central canal; go1, 2, 3, first, second, third generation odontodes; n, node; o, osteocyte spaces; s, sediment; sd, semidentine; vc, vascular canal; vco, vascular canal opening.