Xiphodolamia eoceana, Woodward, 1889

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 : 540

Xiphodolamia eoceana

In Xiphodolamia eoceana fossil teeth, lateral cusplets are absent, and the transverse groove is clearly pronounced. The tooth cervix forms a thin line visible on both the labial and lingual views. The basal ledge is situated lower, with short transverse ridges present on the labial view.

The tooth exhibits an orthodont structure, with folds present on the labial surface of the dentin. The thin enameloid layer is approximately 1/12 the thickness of the pallial dentin. A wide pulp cavity runs along the length of the tooth. The pallial dentin layer is rigid and lacks porosity, while the orthodentin layer contains numerous large dentinal tubules, which are arranged without a specific pattern. The thickness of the enameloid layer constitutes approximately 1/1200 of the total tooth length, while the pallial dentin accounts for about 1/97, and the orthodentin represents roughly 1/8 of the overall tooth length. The osteodentin in the root is rigid and exhibits a homogeneous structure ( Fig. 8E, 8F ).

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.