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

publication ID

https://doi.org/ 10.26879/1085

publication LSID

lsid:zoobank.org:pub:B6B8E985-F1CF-4C10-BB00-602E5BF36C1C

persistent identifier

https://treatment.plazi.org/id/03BA87C1-FFDB-FFCC-C023-E2D3C951B56A

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scientific name

Odontorhytis pappenheimi Böhm, 1926
status

 

Odontorhytis pappenheimi Böhm, 1926

Figure 8 View 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 View 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 View FIGURE 8 1, K, M, N1 View FIGURE 1 ). 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 View FIGURE 8 L-N) compared to the most slender ones, considered here as most anterior ( Figure 8 View 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 View FIGURE 8 2, N2 View FIGURE 2 ). The root is always high, relatively thick and always concave in profile view ( Figure 8K, L, M, N View FIGURE 8 1 View FIGURE 1 ). It bears a well-marked protuberance incised by a median groove ( Figure 8J, N View FIGURE 8 3 View FIGURE 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 View FIGURE 7 ) but the largest ones are also comparable to that of O. pappenheimi (e.g., Figure 7I View FIGURE 7 ). 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.

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