Odontorhytis pappenheimi Böhm, 1926

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 : 24

Odontorhytis pappenheimi Böhm, 1926

Figure 8 I-N

Material. More than 300 teeth from the KEB- 1 locality, Souar-Fortuna formations, Djebel el Kébar, Tunisia, and including the figured specimens ( KEB 1-152 to KEB 1-157; Figure 8 I-N).

Description

Teeth are very numerous from the KEB-1 locality, exceeding a hundred specimens. The tooth-size ranges between 5 and 14 mm in crown elevation. The teeth are nearly symmetrical, mesiodistally compressed, and have a high, sharp, and slanted lingually cusp with an apico-lingual barb observable in lateral view ( Figure 8I 1, K, M, N1 ). The tooth crowns do not seem to change in general morph according size, except the cusp that tends to be shorter and more massive in lateral teeth ( Figure 8 L-N) compared to the most slender ones, considered here as most anterior ( Figure 8 I- K). The enameloid of crown is primarily smooth, except on the basal part of the lingual face, under the barb, where fine folds are often visible. The labio-median cutting edge, when observable, does not reach the base of the crown face ( Figure 8I 2, N2 ). The root is always high, relatively thick and always concave in profile view ( Figure 8K, L, M, N 1 ). It bears a well-marked protuberance incised by a median groove ( Figure 8J, N 3 ).

Remarks

The generic attribution to this uncertain shark, only known from the Paleogene (see Cappetta, 2012; Sambou et al., 2020), is noticeable considering its peculiar tooth morphology. Attribution to the Namibian species Odontorhytis pappenheimi is also sustainable, the latter being characterised by the lack of lateral cusplets, a labio-median cutting edge, and by an apico-lingual barb (Case and Cappetta, 1990; Adnet et al., 2011; Cappetta, 2012) even if Case and Cappetta (1990) and Cappetta (2012) noticed that there were probably several species remaining so far undescribed. Recently, Salame and Asan (2019) described a new species, Odontorhytis bahariensis , from EG, Baharyia Oasis, Egypt. It differs from O. pappenheimi in being smaller (less than 7 mm height), less massive, with a crown relatively higher and in having a labial cutting edge that does not extend to the basal edge of the cusp, as is the case in O. pappenheimi . The smallest teeth documenting this taxon from the KEB-1 locality are quite comparable to those of O. bahariensis (e.g., Figure 7K, N ) but the largest ones are also comparable to that of O. pappenheimi (e.g., Figure 7I ). In fact, the distinction of both species is somewhat tenuous, thereby suggesting that both species are present in KEB-1. Alternatively, we suspect that both species illustrate in fact different ontogenetic stages (see also Sambou et al., 2020) of a unique species. We currently retain the attribution to the formal species O. pappenheimi , pending further studies focused on the heterodonty of this peculiar genus.

Until now, Middle-Late Eocene Odontorhytis pappenheimi and its relatives (e.g., Odontorhytis bahariensis ) were known to be widely distributed in African coastal deposits of late Middle/Late Eocene, particularly well-represented in Egypt (Case and Cappetta, 1990; Murray et al., 2010; Underwood et al., 2011; Adnet et al., 2011). However, it also frequented the Tunisian coast (Sweydan et al., 2018) until to Pakistan area (Case and West, 1991). Underwood et al. (2011) reported the occurrence of O. pappenheimei in MI (Lutetian/ Bartonian boundary) but not in GE (A-C) (Bartonian/Priabonian boundary). As this taxa seems to have preferentially frequented the near shore deposits with fresh water influence (as observed in BQ2 or in interdune lag of QS; Underwood et al., 2011), it is not surprising to have an uncontinuous fossil record for this taxa.

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 2. Locality of KEB-1, Djebel el Kébar, Kasserine region, Tunisia. A, Simplified topographic map of Tunisia locating the Djebel el Kébar in central Tunisia; B, simplified stratigraphical position of fossiliferous level having yielded the fossil-bearing KEB-1 locality; C, photograph showing the typical badlands of variegated clays from the early Tertiary sequence of Djebel el Kébar. See Merzeraud et al. (2016) for precise details about geological settings.

FIGURE 3. A-N: Carcharhinus kasserinensis nov. sp. A. Parasymphyseal upper tooth KEB 1-086, A1. labial view, A2. Lingual view; B. HOLOTYPE Anterior upper tooth KEB 1-087, B1. Labial view, B2. Lingual view, B3. Magnificence of mesial cutting edge; C. Antero-lateral upper tooth KEB 1-088, C1. Labial view, C2. Lingual view; D. Antero-lateral upper tooth KEB 1-089, D1. Labial view, D2. Lingual view; E. Antero-lateral upper tooth KEB 1-226, E1 Lingual view, E2. Labial view; F. Antero-lateral upper tooth KEB 1-227; G. Antero-lateral upper tooth KEB 1-090, G1. Labial view, G2. Lingual view; H. Lateral upper tooth KEB 1-091, labial view; I Posterior upper tooth KEB 1-092, lingual view; J. Symphyseal abnormal lower tooth KEB 1-093, J1. Labial view, J2. Lingual view; K. Anterior lower tooth KEB 1-094, labial view; L. Anterior lower tooth KEB 1-095, L1. Labial view, L2. Lingual view; M. Antero-lateral lower tooth KEB 1- 096, M1. Labial view, M2. Lingual view; N. Antero-lateral lower tooth KEB 1-097, N1. Lingual view, N2. Labial view, N3. Profile.

FIGURE 7. A-C: Hemipristis curvatus. A. Antero-lateral upper tooth KEB 1-133, A1. Lingual view, A2. Labial view; B. Lateral upper tooth of young specimen KEB 1-134, labial view; C. Anterior lower tooth of young specimen KEB 1-135, labial view; D-E: Moerigaleus sp. D. Lateral upper tooth KEB 1-136, D1. Lingual view, D2. Labial view; E. Lateral upper tooth KEB 1-137, E1. Lingual view, E2. Labial view; F-K: Leptocharias tunisiensis nov. sp. F. (HOLOTYPE) Antero-lateral lower tooth KEB 1-138, F1. Profile, F2. Lingual view, F3. Labial view; G. Antero-lateral upper tooth KEB 1-139, G1. Labial view, G2. Profile, G3. Lingual view; H. Anterro-lateral lower tooth KEB 1-140, labial view; I. Lateral lower tooth KEB 1-141, labial view; J. More lateral tooth KEB 1-142, J1. Labial view, J2. Lingual view, J3 occlusal view; K. Posterior tooth KEB 1-143, K1. Labial view, K2. Lingual view.

FIGURE 8. A-C: Nebrius sp. A. Anterior tooth KEB 1-144, A1. Labial view, A2. Lingual view, A3. profile; B. Antero-lateral tooth KEB 1-145, B1. Labial view, B2. Basal view; C. Lateral tooth KEB 1-146, C1. Labial view, C2. Lingual view; D-G: Stegostoma tethysiensis nov. sp. D. (HOLOTYPE) Anterior tooth KEB 1-147, D1. Labial view, D2. Lingual view, D3. Basal view; E. Antero-lateral tooth KEB 1-148, E1. Labial view, E2. Occlusal viex, E3. profile; F. Lateral tooth KEB 1-149, labial view; G. Posterior tooth KEB 1-150, labial view; H: Hemiscyllium sp. 8. Antero-lateral tooth KEB 1-151, labial view; I-N: Odontorythys pappenheimi I.?Anterior tooth KEB 1-152, I1. Profile, I2. Labial view; J.?Latero-posterior tooth KEB 1-153, lingual view; K.?Latero-posterior tooth KEB 1-154, profile; L.?Latero-posterior tooth KEB 1-155, profile; M.?Latero-posterior tooth KEB 1-156, profile; N.? lateral or posterior tooth KEB 1-157, N1. Profile, N2. Labial view, N3. Lingual view.