Rhynchobatus, MULLER AND HENLE, 1837

Cicimurri, David J. & Knight, James L., 2022, Late Eocene (Priabonian) elasmobranchs from the Dry Branch Formation (Barnwell Group) of Aiken County, South Carolina, USA, PaleoBios 36, pp. 1-31 : 18

RHYNCHOBATUS MÜLLER AND HENLE, 1837 RHYNCHOBATUS SP. CF. RHY. PRISTINUS (PROBST, 1877)

( FIG. 6E–H )

Referred specimens —SC2013.38.46, tooth; SC2013.38.47, tooth; SC2013.38.48, tooth.

Remarks —The three teeth are easily distinguished as Rhynchobatus in having granular crown ornamentation and a central lingual protuberance that is long and wide, and flanking protuberances are absent ( Fig. 6E ). Two fossil Rhynchobatus species have been reported, Rhy. vincenti Jaekel, 1894 from Eocene deposits ( Leriche 1905) and Rhy. pristinus from Oligo-Miocene strata ( Cappetta 1970, Cicimurri and Knight 2009). Overall, teeth of these two species are comparable in size and morphology, but Rhy. vincenti has a wider, shorter lingual protuberance than Rhy. pristinus ( Jaekel 1894, Müller 1999). Jaekel (1894:76–77) makes no mention of ornamentation on Rhy. vincenti, and the Dry Branch specimens have a long and narrow protuberance similar to Rhy. pristinus. We tentatively refer the Dry Branch teeth to this latter species due to limited sample available to us. Müller (1999) reported a damaged lower Eocene Rhynchobatus tooth that is similar to Rhy. vincenti, but he did not believe the taxa were conspecific. Although similar, teeth of Pristis differ from those of Rhynchobatus in lacking crown ornamentation, but having a sharp and conspicuous transverse crest. Additionally, Pristis teeth have a shorter lingual face but much more elongated medial uvula ( Cappetta 2012, Carrillo-Briceño et al. 2015, Carrillo-Briceño et al. 2016).

Figures

Figure 6. Batoid teeth from the Dry Branch Formation (Priabonian) of Aiken County, South Carolina. A–D. Rhinobatos sp. Tooth in occlusal (A), labial (B), profile (C), and basal (D) views, SC2013.38.45. E–H. Rhynchobatus sp. cf. Rhy. pristinus. Tooth in occlusal (E), labial (F), profile (G), and basal (H) views, SC2013.38.46. I–P. Dasyatis sp. cf. D. tricuspidatus. Male anterior tooth in labial (I) and distal (J) views, SC2013.38.42. Tooth in labial (K) and occlusal (L) views, SC2013.38.43. Tooth in occlusal (M), labial (N), profile (O), and basal (P) views, SC2013.38.41. Q–Y. Dasyatis sp. SC2013.38.49. Male anterior tooth in labial (Q) and distal (R) views. Tooth in occlusal (S) view, SC2013.38.55. Tooth in occlusal (T), labial (U), and profile (V) views, SC2013.38.52. Tooth in occlusal (W), labial (X), and profile (Y) views, SC2013.38.53. Labial at top in A, D, E, H, L, M, P, S–T, W; at left in C, G, J, O, R, V, Y. Scale bars=1 mm.