Rhynchobatus cf. vincenti Jaekel, 1894

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

Rhynchobatus cf. vincenti Jaekel, 1894

Figure 10 F-G

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

Material. More than 100 oral teeth from the KEB- 1

locality, Souar-Fortuna formations, Djebel el Kébar,

Tunisia, and includes the figured specimens KEB

1-176, 1-177 ( Figure 10 F-G).

Description

Teeth are medium to large sized, reaching more than 3 mm long. The ornamentation of the lingual face, when the latter is not totally abraded by functional wear, is extremely variable, being usually smooth ( Figure 10G ) or having fine enameloid pitting under the transverse keel ( Figure 10F 1 ).

Remarks

Relatively common in most of the Eocene elasmobranch associations, Rhynchobatus displays a tooth morphology particularly conservative, explaining why only three worldwide species are recognised in the fossil record, the Neogene Rhynchobatus pristinus (Probst 1877) and Rhynchobatus rudolffischeri Laurito Mora, 1999 , and the Paleogene Rhynchobatus vincenti Jaekel 1894 . The latter probably corresponds to the frequent species with pitted enameloid occurring along the Fayum series from MI to BQ (Underwood et al., 2011) and often attributed or affiliated to R. vincenti in the Eocene of Tethysian realm (e.g., Cappetta, 2012; Ward and Wiest, 1990; Averianov and Udovinchenko, 1993; Mustafa and Zalmout, 2002; Tabuce et al., 2005; Strougo et al., 2007).

Figures

FIGURE 1. Paleotemperatures (ice-free deep-ocean T°/ tropical sea surface T°) and Thermic events during the “doubthouse” conditions of Eocene period (from Cramwinckel et al., 2018 modified with events dating from Hollis et al., 2019). Stratigraphically and geographical locations of the main deposits with Elasmobranch associations along the southwestern Tethys. Abbreviations: DAK: Dakhla (Adnet et al., 2010), GEN: Genam (Zouhri et al., 2017, in press); AZ: Aznag (Tabuce et al., 2005) PM: Phosphate ores (see Noubhani and Cappetta, 1997), Morocco; GAF: Gafsa basin (see Arambourg, 1952); KEBAR: Kébar (this work and Adnet et al., 2019); MBK: Mabrouk (see Sweydan et al., 2019), Tunisia; EG: ElGedida (see Strougo et al., 2007); KM: KM11 (see Adnet et al., 2011) MT: Minqar Tabaghbagh (see Zalmout et al., 2012); BQ: Birquet Qarun QS: Quar et Sa; GE: Genahamm Fm.; MI: Midawara FM. from Wadi al Hitan, see Underwood et al., 2011), Egypt; QD: Qa Faydat al Dahikya, Jordania, see Mustafat and Zalmout, 2002).

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.