Torpedo sp.

Adnet, Sylvain, Marivaux, Laurent, Cappetta, Henri, Charruault, Anne-Lise, Essid, El Mabrouk, Jiquel, Suzanne, Ammar, Hayet Khayati, Marandat, Bernard, Marzougui, Wissem, Merzeraud, Gilles, Temani, Rim, Vianey-Liaud, Monique & Tabuce, Rodolphe, 2020, Diversity and renewal of tropical elasmobranchs around the Middle Eocene Climatic Optimum (MECO) in North Africa: New data from the lagoonal deposits of Djebel el Kébar, Central Tunisia, Palaeontologia Electronica (a 38) 23 (2), pp. 1-62 : 28-29

? Torpedo sp. Figure 10 H-I

2016 Torpedo sp. ; Merzeraud et al., p. 14-15, tab. 1.

Material. Two rare and fragmentary teeth from the KEB- 1 locality, Souar-Fortuna formations, Djebel el Kébar, Tunisia ( KEB 1-178 and 1-179; Figure 10 HI).

Description

These two teeth of? Torpedo sp. have broken cusps, reducing the reliability of systematics determination among the Torpediniformes . The teeth measure less than 2 mm in width. The crown is laterally elongated and seems well cuspidate. Labial and lingual ornamentations are missing on the whole enameloid surface of the crown. The labial face of the crown is slightly convex from the base of cusp to the labial visor that largely overlaps the root-crown boundary in profile. The labial visor marks a transversal rounded bulge. The transversal crest between the lingual and labial faces is lacking, except near the broken cusp where it appears sharped toward the cusp apex ( Figure 10I ). The lingual face is sub-rectangular, its marginal edges being quite vertical and its basal edge being slightly concave in lingual view ( Figure 10 HI). A narrow collar is visible on both views. The root is high with flattened lobes separated by a broad groove. The nutritive foramen is oriented lingually in the median groove, opening just below the crown/root boundary.

Remarks

Cappetta (1988) has figured teeth of most of the extant genera of Torpediniformes. The tooth morphology observed in the scarce sample from the KEB-1 locality (with the presence of a sub-rectangular lingual face, lack of salient transversal crest along the entire crown length, singular orientation of nutritive foramen) reminds the morphology usually observe in torpedinins like Torpedo or Tetronarce rather than that characterizing narcinins/ narkinins like Narcine, Narke, Temera, and Tetronarcine for instance. Torpedo is known in the Priabonian of the Fayum area (BQ and upper QS; Underwood et al., 2011) and was signalled since the Palaeocene elsewhere (Cappetta, 2012). Benoit et al. (2013) reported the presence of a unique torpediniform tooth (? Narcine sp.) in the Ypresian – early Lutetian fossil mammal-bearing locality of Djebel Chambi in Tunisia, a fossiliferous locality close to those of Djebel el Kébar. The specimen from Chambi resembles in some aspect to the material reported by Cappetta (1988) as Narcine sp. from the late Ypresian of Ouled Abdoun, Morocco, and besides it is different from those recovered in youngest deposits of Djebel el Kébar.

Figures

FIGURE 10. A-D: Propristis cf. schweinfurti. A. Rostral denticle KEB 1-172, A1. Profile, A2. dorsal view; B. Rostral denticle KEB 1-173, Profile; C. Rostral denticle KEB 1-174, C1. Profile, C2. Dorsal view, C3. basal view; D. Rostral denticle KEB 1-175, D1. profile. D2. dorsal view; E: Pristis sp. Rostral denticle, KEB 1-165, dorsal view; F-G. Rhynchobatus cf. vincenti. F. anterior tooth KEB 1-176, F1. Occlusal view, F2. Basal view; G. anterior tooth KEB 1-177, occlusal view; H-I.?Torpedo sp. H. lateral tooth KEB 1-178, occlusal view, I. lateral tooth KEB 1-179, occlusal view.