FIGURE 6 in Holocephalan (Chondrichthyes) dental plates with hypermineralized dentine as a substitute for missing teeth through developmental plasticity

FIGURE 6 Harriotta raleaghana μCT-scans. (a)–(e) Upper dentition in oral view. (a) Anterior and posterior dental plate showing close fit between them and tritoral pad on posterior plate. (b) Anterior dental plate with posterior dental plate cut away to show posterior and lingual faces of the anterior plate, lacking prominent ridges on the lingual surface of the dental plate, but with some bulbous expansion that was associated with ridges in Chimaera (Figure 2), indicated by the arrow. (c) Four upper dental plates rendered (Avizo) showing ovoids and rods (whitlockin) as extensive below the worn surface, and developing tritoral pads on the posterior plate. Ovoids in symphyseal row with antero-labial set of rods in anterior plate. (d) Anterior dental plate, virtual section through developing rod (whitlockin), surrounding trabecular dentine, sclerotic dentine near the wear surface, and trabecular dentine only at forming aboral surface. (e) Symphyseal surface with opposing left plates cut away, showing the anterior dental plate (arrow 2 marks the antero-symphyseal portion) and posterior in close alignment at the oral surface (arrow 1). Abbreviations as in previous figures