Carcharhinus sp.

Vliet, Hendrik Jan Van, Schulp, Anne S., Abu El-Kheir, Gebely A. M. M., Paijmans, Theo M., Bosselaers, Mark & Underwood, Charles J., 2017, A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the Western Desert of Egypt, Acta Palaeontologica Polonica 62 (3), pp. 509-525 : 518

Carcharhinus sp.

Fig. 12A, F .

Material.—15 teeth (CGM67191: five, CGM67195: ten) from the BOTM and BOS, early Oligocene, Minqar Tibaghbagh, Qattara Depression, Egypt. Dimensions: height 9–13 mm, width 8–16 mm.

Description.—Teeth of this species show a low degree of heterodonty, and the slender tooth morphology usually associated with Carcharhinus lower teeth appears to be absent. Whilst upper teeth commonly outnumber lowers in collections of fossil Carcharhinus teeth (CJU personal observation), slender lowers are typically seen in any moderate sized sample and clearly differentiated from broader upper teeth. This is not the case with this species and it therefore appears that strong dignathic heterodonty was absent.

Teeth are moderately compressed linguolabially and are either of similar height and width or slightly wider than high. The cusp is robust and inclined distally. The distal part of the tooth crown comprises a low distal heel that barely rises above the top of the root. There is a well-developed notch between the cusp and heel. The cutting edge of the crown is covered with small but prominent serrations of regular size and spacing. The root is high and has a rather concave basal face. A lingual nutritive groove is seen in some teeth.

Remarks.—The material here described cannot be readily assigned to any known species, but is considered unsuitable to use as a basis for the description of a new taxon.

Carcharhinus spp. from the Daba’a Formation at Minqar Tibaghbagh has been described by Van Vliet and El-Kheir 2010) and Zalmout et al. (2012). The genus Carcharhinus is known from the Lutetian to Recent of Europe, North America, Africa, Asia, Australia, Japan and New Zealand Cappetta 2012).

Carcharhinus cf. perseus Adnet, Antoine, Hassan Baqri, Crochet, Marivaux, Welcomme, and Métais, 2007

Fig. 12E .

Material.—Three teeth (CGM67194), two badly damaged; from the BOS, early Oligocene, Minqar Tibaghbagh, Qattara Depression, Egypt. Dimensions: height 9–12 mm, width 10–12 mm.

Description.—Carcharhinids belonging to the “bull-group” with only little dignathic heterodonty, but more than in Carcharhinus sp. (above). Teeth of the upper and lower jaws are broad and blade-like. Teeth of the lower jaw are slightly more slender and the serration is less coarse. The crown of both upper and lower teeth is smaller than the linguolabially compressed root. Crown and root are equally flat at the lingual and labial sides. There is a weak lingual nutritive groove on the root, less pronounced and sometimes even absent in teeth from the upper jaw. The complete tooth is from the upper jaw. Remarks.—The material present here is considered insufficient in quality or quantity to assign without doubt to Carcharhinus perseus , but it is either conspecific or a very similar species. Carcharhinus perseus Adnet, Antoine, Hassan Baqri, Crochet, Marivaux, Welcomme, and Métais, 2007 was originally recorded from the early Oligocene (Rupelian) Bugti Member, Chitarwata Formation of Balochistan, Pakistan ( Adnet et al. 2007). It was later recognized in the earliest Oligocene Jebel Qatrani Formation of the Fayum Depression of Egypt in Africa ( Murray et al. 2014).

Figures

Fig. 12. A–C. Carcharhiniformes and Myliobatiformes from the BOTM, early Oligocene, Minqar Tibaghbagh, Qattara Depression, Egypt; photographed and left in the field. A. Carcharhinus sp., incomplete upper tooth in lingual view. B, C. “Aetobatus” sp. B. Lower tooth in occlusal (B1) and basal (B2) views. C. Lower tooth in occlusal view. D–M. Carcharhiniformes and Lamniformes from the BOS, early Oligocene, Minqar Tibaghbagh, Qattara Depression, Egypt. D. Hemipristis cf. serra Agassiz, 1835 (1843) (CGM67195), upper lateral teeth in lingual (D1, D2, D4) and labial (D3) views. E. Carcharhinus cf. perseus Adnet,Antoine, Hassan Baqri, Crochet, Marivaux, Welcomme, and Métais, 2007 (CGM67194), upper antero-lateral teeth in lingual view. F. Carcharhinus sp. (CGM67195), upper teeth in lingual (F1, F4, F5, F6) and labial (F2, F3) views. G. Negaprion frequens (Dames, 1883) (CGM67191), lower teeth in lingual (G1, G3, G4) and lateral (G2, G5) views. H. Galeocerdo sp. (CGM67195) in lingual view. I–L. Otodus (Carcharocles) cf. sokolowi. I. CGM67195, upper tooth in lingual view. J. CGM69186 upper tooth in lingual (J1) and labial (J2) views. K. CGM69186, lower tooth in labial view. L. CGM69186, lower tooth in lingual (L1) and labial (L2) views. M. Carcharias? sp. (CGM67195), lower teeth in lateral (M1) and lingual (M2) views.