Nebrius sp.
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publication ID |
https://doi.org/ 10.26879/1085 |
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publication LSID |
lsid:zoobank.org:pub:B6B8E985-F1CF-4C10-BB00-602E5BF36C1C |
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persistent identifier |
https://treatment.plazi.org/id/03BA87C1-FFDF-FFCE-C517-E3A3CC4BB6F9 |
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treatment provided by |
Felipe |
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scientific name |
Nebrius sp. |
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Figure 8 View FIGURE 8 A-C
2016 Nebrius cf. obliquus ; Merzeraud et al., p. 14-15, tab. 1.
Material. About 30 teeth from the KEB- 1 locality,
Souar-Fortuna formations, Djebel el Kébar, Tunisia are identified, including the figured specimens KEB
1-144 to KEB 1-146 ( Figure 8 View FIGURE 8 A-C).
Description
Anterior teeth are almost symmetrical and broader than high ( Figure 8A View FIGURE 8 ). In labial view ( Figure 8A View FIGURE 8 1 View FIGURE 1 ), the mesial and distal cutting edges are virtually straight to slightly convex and indented by seven to eight well-separated serrations. The main cusp is clearly more developed than the marginal serrations but not as protruding. In profile ( Figure 8A View FIGURE 8 3 View FIGURE 3 ), the labial face is almost straight and the lingual one clearly concave. The base of the labial face of the crown bears a salient and symmetrical apron. The root is thick, with a cloverleaf-shaped outline in basal view ( Figure 8B View FIGURE 8 2 View FIGURE 2 ). A broad and deep elliptical foramen opens in the centre of the face. In more lateral teeth ( Figure 8B View FIGURE 8 ), the morphology of the crown is quite similar to the previous, except the distal cutting edge that bears serrations, which are more erected than those of the mesial edge. The apron is more developed, asymmetrical, and longer in labial view. In posterior teeth ( Figure 8C View FIGURE 8 ), the crown is much more inclined distally, the mesial cutting-edge bears nine to ten serrations whereas the distal one, much shorter and straight, bears only four serrations.
Remarks
Nebrius obliquus (Leidy, 1877) and Nebrius thielensis (Winkler, 1874) are common carpet sharks recovered in the Middle-Late Eocene tropical nearshores deposits from the paleo-Caribbean (Leidy, 1877; Kruckow and Thies, 1990; Cappetta and Case, 2016, Ebersole et al., 2019) to Pakistan (Case and West, 1991; Adnet et al., 2007) including Aznag in Morocco (Tabuce et al., 2005) and KM, Egypt (Adnet et al., 2011) for instance. Among the other Eocene species assigned to the genus Nebrius , two come from the Middle/Late Eocene of Egypt, Nebrius blanckenhorni (Stromer, 1903) and Nebrius fourtaui (Priem, 1905) . If Noubhani and Cappetta (1997) already synonymized N. fourtaui with N. obliquus , the teeth of N. blanckenhorni have a morphology reminiscent to that of N. obliquus , and as such both species are probably synonymous (e.g., Cappetta and Case, 2016), even if this first is always signalled in Late Paleogene deposits (Samonds et al., 2019). Ebersole et al. (2019) recently discussed about the tooth differences between N. obliquus and N. thielensis and suggested that they seem rather a reflection of heterodonty than separate species, at least concerning the post Ypresian representatives. Considering these recent observations and the doubt about systematics validity, this Nebius representative from Bartonian is left in open nomenclature. Underwood et al. (2011) also reported the presence of Nebrius from MI to QS. Strougo et al. (2007) do not reported the presence of Nebius at EG, but a re-examination of the material from this locality (pers. observ.) allows us to confirm the presence of Nebrius in EG.
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