Fig. 14

Harriotta raleighana (Rhinochimeridae; Holocephali; Chondrichthyes). Magnesium (Mg), Calcium (Ca) and Phosphorus (P) sEDX line plots comparing different regions of upper rostral plate. a, b reflected light and BSE of labial ovoids, line plots (ov1, 1; ov2, 2) and lingual rod (rod, 3) separated by sclerotic dentine. EDX analyses from aboral to oral, red lines, 1–3 also for tissue types (see Fig. 1a, Fig. 5a, Fig. 7a), × 6.5, × 7. c plots 1–3, 1 crosses the empty non-mineralized, two labial ovoids; plot 2 has one ovoid with irregular mineralization (white in A, ov1–1) and incomplete mineralization of second; plot 3 crosses a lingual rod that is fully mineralized orally, with transitional mineralization aborally. Comparing these regions of forming hypermineralized dentine for Ca, P, and Mg values, shows that in plot 1 the trabecular dentine (TD) has higher values than the ovoid space, but itself has two spaces between mineralization peaks, an increase in Mg for each peaks; ov1–2 has begun to mineralize, with Mg up too. Plot 2, Mg increases with increase of Ca and P, higher than trabecular dentine. Ovoids have more mineral than the trabecular dentine with an unmineralized gap between. Plot 3 along the rod, after a slightly lower level aborally, has a continuous high level of mineral, about the same value as in the ovoids, including elevation of Mg. Key to plots, green- Mg; blue- Ca; red- P