Moerigaleus 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 : 18

Moerigaleus sp. Figure 7 D-E

2007 “ Galeorhinus ” sp.; Strougo et al., p. 88-94.

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

Material. Two teeth KEB 1-136 and 1-137 (Figure

7D-E) and rare broken upper and lower teeth from the KEB- 1 locality, Souar-Fortuna formations,

Djebel el Kébar, Tunisia.

Description

The crown is either unornamented on the two specimens. Teeth are strongly compressed labiolingually and the cusp is relatively high compared with the root. The upper anterolateral tooth ( Figure 7D ) bears a pair of short but sharp and divergent lateral denticles on its distal cutting edge, and a pair of minute hook-shaped denticles on its mesial cutting edge. The second tooth ( Figure 7E ), possibly from the lateral lower file, is quite similar except the lack of marked cusplets in both sides of the main cusp. The rare material available here reminds those of the unique species M. vitreodon from the Late Eocene, but as it is also present in other faunas close to the Lutetian-Bartonian boundary and still under study (Underwood and Ward, 2011, p. 708), we preferred to leave it in open nomenclature waiting for supplementary figurations.

Remarks

Representing one of the earliest records of the Hemigaleidae with Hemipristis , the dentition of Moerigaleus differs from that of other members of the family in the dignathic heterodonty, which is far less well developed but monognathic heterodonty is at least as extreme. This genus was described from BQ (Underwood and Ward, 2011), but occurred from the Fayum region ranging in age from the Lutetian-Bartonian to late Priabonian (Underwood and Ward, 2011). Some teeth recovered in EG (pers. observ. SA, HC) and probably attributed to “ Galeorhinus ” sp. in Strougo et al. (2007) belong in fact to this genus. This new report, even unnamed, therefore adds to the known geographical range of this taxon.

Figures

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.