Archaeomanta 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 : 44

Archaeomanta sp.

Figure 14H

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

Material. Material consists of 11 fragmentary teeth, none with complete crown, from the KEB- 1 locality, Souar-Fortuna formations, Djebel el Kébar, Tunisia, and includes the unique figured specimen KEB 1-225 ( Figure 14H ).

Description

Teeth of this genus are clearly distinctive in having a rather high crown, compressed mesio-distally with apex that bends strongly lingually. The cusp curves suddenly lingually at a certain distance from the ovoid base of the crown. Cusps do not bear the usual mediolabial cutting edge nor the mediolingual cutting edge on the apical region. The root is robust ( Figure 14H 1 ), globular with a basal face longer than broad, convex, with a heart-shaped contour, and a narrow and shallow axial groove (sometimes with secondary labiolingually orientated grooves).

Remarks

This taxa is usually attributed to mobulids based on its peculiar tooth morphology reminding that of some Mobula with peg-like teeth, but the presence of a large pulp cavity extending to the tip of the cusp (Underwood et al., 2011) makes their supposed position within the mobulids very doubtful (see also Adnet et al., 2012). However, the enameloid of Archaeomanta (Enault et al., 2013) is very thin and closely resembles that of extant Mobulidae or fossil and extant Gymnuridae (e.g., Jacquhermania , Gymnura ). Three species of Archaemanta are currently known in the fossil record. It concerns the Thanetian Archaeomanta priemi Herman and Crochard, 1979 , the Ypresian Archaeomanta melenhorsti Herman and Crochard, 1979 , and the Lutetian Archaeomanta hermani Kozlov, 2001 . A morphological distinction between these chronospecies is evident, notably between the two firsts, known by numerous specimens. Indeed, teeth of A. melenhorsti have more mesiodistally compressed crowns with more elongated and distally oriented cusps and a deep, straight groove on roots compared with A. priemi that possesses a peculiar large collar at base of crowns (Herman and Crochard, 1979). In contrast, A. hermani shows an extreme long cusp strongly compressed mesiodistally compared with those observable in both older species. The morphology of the Bartonian KEB- 1 specimens is clearly different from that of these three species in having more globular and robust roots (compared to A. melenhorsti and A. hermani ), a tooth cusp without any median cutting edge (compared to A. melenhorsti , A. priemi , and? A. hermani ), and no marked collar (compared to A. priemi ). However, the bad state of preservation of specimens does not allow to provide a detailed description of this unnamed species. Often rare in Paleogene deposits, this genus is nevertheless widely distributed in the Middle-Late Eocene of the peri-Tethysian realm (Cappetta, 2012), including in EG (Strougo et al., 2007), in the Priabonian of Egypt (upper GE to QS in Underwood et al., 2011), and in Southwestern Morocco (Adnet et al., 2010), even if the species status is always left in open nomenclature.

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 14. A-G. Amamriabatis heni nov gen. nov. sp. A. anterior tooth KEB 1-218, A1. Occlusal view, A2. Basal view, A3. Lingual view, B. antero-lateral tooth KEB 1-219 (Holotype), B1. Occlusal view, B2. Lingual view, B3. Basal view, C. juvenile tooth KEB 1-220, occlusal view, D. antero-lateral tooth KEB 1-221, D1. Occlusal view, D2. Basal view, D3. Labial view, E. lateral tooth KEB 1-222, E1. Occlusal view, E2. Lingual view, E3. Basal view, F. antero-lateral tooth KEB 1-223, F1. Occlusal view, F2. Basal view, F3. Labial view, G. lateral tooth KEB 1-224, G1. Occlusal view, G2. Basal view, G3. Lingual view; H. Archaeomanta sp. KEB 1-225, H1. Lateral view, H2. Labial view.