Sphyrna 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 : 16

? Sphyrna sp.

Figure 6 D-F

Material. KEB 1-123 to 1-125 ( Figure 6 D-F) consists of 10 upper and lower teeth from the KEB- 1 locality, Souar-Fortuna formations, Djebel el Kebar, Tunisia.

Description

Upper teeth are relatively small (3.5 mm in length). The cusp is relatively fine and high in the mesio-distal axis; the mesial cutting edge is straight ( Figure 6D ) to slightly concave ( Figure 6 EF), and bears fine serrations on its more mesial part, marking sometimes a small notch. The distal heel is well developed, rounded and also finely serrated. The root is broader than the crown, both in antero-lateral ( Figure 6 D-E) and lateral teeth ( Figure 6F ); root lobes are well aligned, horizontal and separated by a straight nutritive groove.

Remarks

Compared with the former described species, a few teeth of small size were provisionally attributed to another species of Sphyrna . The latter, illustrated by upper teeth, presents a dental pattern that reminds those of small individuals of Sphyrna guinoti nov. sp. ( Figure 5A ), except that the crown sometimes shows mesial and distal heels with a short and fine serration. Teeth are moreover more labiolingually compressed and lesser expended mesiodistally compared with those usually reported for S. guinoti nov. sp. Alternatively, they could document to a tooth morphology of juvenile of S. guinoti nov. sp. due to the scarcity of the material, this species was left in open nomenclature.

Figures

FIGURE 5. A-K: Sphyrna guinoti nov. sp. A. Anterior upper tooth KEB 1-109, A1. Labial view, A2. Lingual view; B. Lateral upper tooth KEB 1-110, B1. Labial view, B2. Lingual view; C. Anterior upper tooth KEB 1-111, C1. Lingual view, C2. Labial view; D. Lateral lower tooth KEB 1-112, D1. Labial view, D2. Lingual view; E. lateral upper tooth KEB 1-113, E1. Lingual view, E2. Labial view; F. Lateral upper tooth KEB 1-114, F1. Labial view, F2. Lingual view; G. Posterior upper tooth KEB 1-115, lingual view; H. Anterior lower tooth KEB 1-116, H1. Labial view, H2. Lingual view; I. Antero-lateral lower tooth KEB 1-117, I1. Labial view, I2. Lingual view; J. (HOLOTYPE) Antero-lateral lower tooth KEB 1-118, J1. Labial view, J2. Lingual view; K. Lateral lower tooth KEB 1-119, K1. Labial view, K2. Lingual view.

FIGURE 6. A-C: Sphyrna guinoti nov. sp. A. Anterior upper tooth of Young specimen KEB 1-120, A1. Lingual view, A2. Labial view; B. Lateral lower tooth of Young specimen KEB 1-121, B1. Labial view, B2. Lingual view; C. Lateral upper tooth KEB 1-122, C1. Labial view, C2. Lingual view; D-F:?Sphyrna sp. 4. D.?Antero-lateral upper tooth KEB 1-123, D1. Lingual view, D2. Labial view; E.?Antero-lateral upper tooth KEB 1-124, E1. Labial view, E2. Lingual view; F. Lateral upper tooth KEB 1-125, lingual view.