Glyphis sp.

Jirapatrasilp, Parin, Cuny, Gilles, Kocsis, László, Sutcharit, Chirasak, Ngamnisai, Nom, Charoentitirat, Thasinee, Kumpitak, Satapat & Suraprasit, Kantapon, 2024, Mid-Holocene marine faunas from the Bangkok Clay deposits in Nakhon Nayok, the Central Plain of Thailand, ZooKeys 1202, pp. 1-110 : 1-110

Glyphis sp.

Figs 23 , 24 , 25 , 26 , 27 , 28

Referred material.

CUF - NKNY - 8.2 (Fig. 23 A – H ), CUF - NKNY - Q 03 (Fig. 24 A – H ), CUF - NKNY - S 5 - 2, CUF - NKNY - S 5 - 4, CUF - NKNY - S 5 - 6, CUF - NKNY - S 5 - 7, CUF - NKNY - SA- 2 to 5, CUF - NKNY - SA- 7, CUF - NKNY - SA- 8, CUF - NKNY - SB- 1, CUF - NKNY - SB- 4 to 9, CUF - NKNY - SC- 1, CUF - NKNY - SC- 3 (Fig. 25 A – E ), CUF - NKNY - SC- 4, CUF - NKNY - SC- 6, CUF - NKNY - SC- 8, CUF - NKNY - SC- 9, CUF - NKNY - SD 1 to 3 (Fig. 25 F – J ), CUF - NKNY - SD 6, CUF - NKNY - SD - 8 to 10, CUF - NKNY - SE 1 to 2, CUF - NKNY - SE- 4 to 7, CUF - NKNY - SE- 10 to 15, CUF - NKNY - SE- 17 to 18 (46 upper teeth), CUF - NKNY - 14 (Fig. 26 A – H ), CUF - NKNY - S 1 - 1 to 4 (Fig. 26 I – M ), CUF - NKNY - S 3 - 1 (Fig. 27 A – E ), CUF - NKNY - S 3 - 5 to 6 (Fig. 27 F – J ), CUF - NKNY - S 4 - 1 to 2 (Fig. 28 A – E ), CUF - NKNY - S 4 - 4 to 6 (Fig. 28 F – J ) (13 lower teeth).

Description.

Many teeth are poorly preserved. The crown of the upper teeth is triangular in outline, with a concavity at the base on both the mesial and distal sides in labial and lingual view, although the distal one is better marked, especially in anterior teeth (CUF - NKNY - S 5 - 7). The serrations are quite fine and homogeneous in size along the cutting edges. The crown is strongly compressed labio-lingually and may be slightly curved lingually. When being broken, the crown displays a pulp cavity compressed labio-lingually, indicating an orthodont tooth histology (CUF - NKNY - SE- 11). The base of the root is slightly concave in labial or lingual view. A well-developed nutritive groove and / or a nutritive foramen may be present on the lower half of the lingual side of the root.

The lower teeth may reach 40 mm in height. They are narrower and less compressed labio-lingually than the upper ones. The enameloid is smooth and the labial face of the crown is flatter than the lingual one. The main cusp is inclined lingually, sometimes with a sigmoid outline (CUF - NKNY - S 4 - 2, CUF - NKNY - S 4 - 5). Three different crown morphologies are noted. (1) On the specimens CUF - NKNY - S 1 - 1, CUF - NKNY - S 1 - 2, and CUF - NKNY - S 1 - 4, the crown is devoid of heels and the tip of the main cusp is spearhead-shaped, the latter being regularly serrated, whereas the rest of the crown is smooth. (2) The specimens CUF - NKNY - S 4 - 1 and CUF - NKNY - S 4 - 4 have a narrow and upright triangular main cusp devoid of serration, showing a tiny accessory cusplet on each side of the main cusp in CUF - NKNY - S 4 - 4 or only lingually in CUF - NKNY - S 4 - 1. (3) On the specimen CUF - NKNY - S 3 - 6, the main cusp is also upright, narrow, triangular in shape, and serrated on their mesial and distal edges. Well-developed heels are present on each side of the main cusp, separated from the latter by a notch. The heel is sometimes less marked on the mesial side (CUF - NKNY - S 3 - 1). The heels display less developed serration than on the main cusp. Many teeth belonging to this morphotype display a broken apex of the main cusp (CUF - NKNY - 14).

The root displays a bulged lingual face. It is more massive and more arched in spearhead-shaped teeth than in heeled ones. There is a nutritive groove in the lingual side of the root with a nutritive foramen in its middle part that can be observed in most of the teeth. The specimen CUF - NKNY - S 1 - 1 displays a double groove.

Taxonomic remarks and comparisons.

Upper anterior teeth (CUF - NKNY - Q 03) are more erect and narrower than the lateral ones (CUF - NKNY - 8.2). Lower teeth with a spearhead-shaped apex correspond to the larger teeth in our sample, in agreement with the fact that this morphology is known only in anterior teeth of adult specimens of Glyphis glyphis and G. garricki . However, lateral teeth of these species display serrated heels and teeth of juveniles can display a pair of tiny lateral cusplets ( Compagno et al. 2008; White et al. 2015). As a result, the three lower tooth morphotypes described above could be encountered into a single species during its ontogeny. Otherwise, it could indicate the presence of more than one species, possibly three: G. glyphis , G. garricki , and G. gangeticus , as the latter species often possesses anterior lower teeth with tiny lateral cusplets but lacks the spearhead-shaped apex ( Roberts 2006; Cappetta 2012). Consequently, the teeth described above are left in open nomenclature as Glyphis sp. This taxon appears to be most common in the studied fauna, although the discrepancies between the number of upper and lower teeth recovered suggest some degree of collecting bias.

The genus is specific to the Indo-West Pacific tropical region and often referred as “ river shark ” due to its habitat in or nearby rivers and estuaries. They are quite rare, hence difficult to study. Five living species are known ( Froese and Pauly 2024), but DNA analyses suggest that some of these are conspecific ( Li et al. 2015). On the other hand, teeth of Glyphis are often recorded from Southeast Asia ( Shimada et al. 2016; Kocsis et al. 2019 and references therein).

Scoliodon Müller & Henle, 1837

Figures

Figure 23. Carcharhinid shark teeth - Glyphis sp. specimen CUF - NKNY - 8.2, upper lateral tooth in A lingual B labial C mesial D distal and E apical views F – H close-ups of the serration F at the base of the cusp mesial cutting-edge, G at the tip of the cusp and H on the distal heel.

Figure 24. Carcharhinid shark teeth - Glyphis sp. specimen CUF - NKNY - Q 03, upper anterior tooth in A lingual B labial C mesial D distal and E apical views F – H close-ups of the serration F at the base, G in the middle and H in the upper part of the cusp mesial cutting-edge.

Figure 25. Carcharhinid shark teeth - Glyphis sp. A – E specimen CUF - NKNY - SC- 3, upper anterolateral tooth in A lingual B labial C mesial D distal and E apical views F – J specimen CUF - NKNY - SD - 3, upper lateral tooth in F lingual G labial H mesial I distal and J apical views.

Figure 26. Carcharhinid shark teeth - Glyphis sp. A – H specimen CUF - NKNY - 14, lower tooth in A lingual B labial C mesial D distal and E apical views F – H close-ups on the serration F on the distal heel, G at the base of the cusp distal cutting-edge and H in the middle part of the cusp mesial cutting-edge I – M specimen CUF - NKNY - S 1 - 2, lower anterior tooth in I lingual J labial K mesial L distal and M apical views.

Figure 27. Carcharhinid shark teeth - Glyphis sp. A – E specimen CUF - NKNY - S 3 - 1, lower tooth in A lingual B labial C mesial D distal and E apical views F – J specimen CUF - NKNY - S 3 - 6, lower tooth in F lingual G labial H mesial I distal and J apical views.

Figure 28. Carcharhinid shark teeth - Glyphis sp. A – E specimen CUF - NKNY - S 4 - 1, lower tooth in A lingual B labial C mesial D distal and E apical views F – J specimen CUF - NKNY - S 4 - 4, lower anterior tooth in F lingual G labial H mesial I distal and J apical views.