Xiphodolamia ensis (Leidy, 1877)

Artüz, M. Levent & Sakinç, Mehmet, 2025, Description of a new species, Xiphodolamia maliki sp. nov. and the shark teeth of Middle Eocene (Lutetian) aged Soğucak Formation in Küçükçekmece, Istanbul, Turkey, Zootaxa 5646 (4), pp. 527-544 : 538

Xiphodolamia ensis

The fossil teeth of Xiphodolamia ensis are characterised by the absence of lateral cusplets and a well-defined transverse groove. The tooth cervix appears as a fine line on both the labial and lingual views. Similar to X. eoceana , the basal ledge in X. ensis is positioned lower, with short transverse ridges visible on the labial side.

The tooth exhibits an orthodont structure, with a thin enameloid layer featuring folds on the labial surface of the dentin constituting approximately 1/1236 of the total tooth length. The enameloid layer is approximately 1/12 the thickness of the pallial dentin. A large pulp cavity runs axially through the tooth, with the enameloid making up about 1/1236 of the total tooth length, the pallial dentin accounting for 1/99, and the orthodentin roughly 1/9 of the overall length. The pallial dentin layer is rigid and lacks porosity, while the orthodentin contains numerous large dentinal tubules, which are not organised in a specific pattern. The pulp cavity is distinctly thicker than the dentinal tubules. The osteodentin in the root is rigid and displays a homogeneous structure ( Fig. 8C, 8D ).

Figures

FIGURE 8. Internal tooth structure of Xiphodolamia barbadica (right anterolateral tooth) A (Axial) and B (Transversal) in back-scattered mode, Xiphodolamia ensis (right anterolateral tooth) C and D, Xiphodolamia eoceana (left anterolateral tooth) E and F, and Xiphodolamia maliki sp. nov. (right anterolateral tooth) G and H in axial views and labiolingual axial cross-sections at the neck of the tooth. a) Enameloid; b) Pallial dentin; c) Orthodentin with dentinal tubules; d) Pulp cavity; e) Single row of dentinal tubules at the interface between pallial dentin and orthodentin (pallial dentin–orthodentin junction). Scale bar 500 µm.