Rhinoptera, Cuvier, 1829

Cicimurri, David J. & Knight, James L., 2009, Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA, Acta Palaeontologica Polonica 54 (4), pp. 627-647 : 641

Rhinoptera cf. R. studeri (Agassiz, 1843)

Fig. 6G .

Referred specimens.—BCGM 9122 and 9123, SC 2009.18.24.

Comments.—These teeth differ from those of Myliobatinae gen. indet. in having labial and lingual crown ornamentation consisting of fine vertical wrinkles (as opposed to having a granular texture), and the lingual basal ridge is thick and rounded (as opposed to rather narrow and sharp). In these respects, the Chandler Bridge teeth are quite similar to Rhinoptera studeri from the European Miocene ( Leriche 1927; Cappetta 1970, 1987), but a specific assignment cannot be made with confidence because our sample size is small and the material incomplete. A specimen from the Belgrade Formation of North Carolina was identified as Rhinoptera aff. R. bonasus Mitchill, 1815 by Müller (1999: pl. 15: 7), but it does not appear to be different than a tooth of R. studeri illustrated by Leriche (1927: pl. 6: 3). Other teeth from the Belgrade Formation were identified as Rhinoptera aff. R. brasiliensis Müller, 1835 by Müller (1999: pl. 15: 4, 5), but the inter− and intraspecific variation in extant Rhinoptera (i.e., Cappetta 1987) suggests that only a single species was present during deposition of the Belgrade Formation. The North Carolina and Chandler Bridge specimens appear to be conspecific, but a larger sample is needed to make a more accurate determination. Rhinoptera may have been more widespread during the Oligocene than previously indicated, as Rupelian specimens identified as Myliobatis by Genault (1993: figs. 65, 66), Baut and Génault (1999: pl. 7: 3), and Reinecke et al. (2001: pl. 55: A, B) possess the same attributes as Chandler Bridge teeth we refer to Rhinoptera .

Stratigraphic and geographic range.—?Oligocene (Chattian), USA (North and South Carolina); Miocene, Europe.

Figures

Fig. 6. Batoids from Summerville, upper Chattian. A. Rhynchobatus pristinus (Probst, 1877), BCGM 9085, occlusal view. B, C. Myliobatinae gen. indet. B. BCGM 9117, lateral tooth, occlusal view. C. BCGM 9116, partial medial tooth, occlusal (C1) and lingual (C2) view. D. Paramobula fragilis (Cappetta, 1970), BCGM 9113, anterolateral tooth, occlusal (D1), labial (D2), and lateral (D3) view. E, F. Plinthicus stenodon Cope, 1869. E. BCGM 9120, partial anterior tooth, lateral (E1) and lingual (E2) view. F. BCGM 9121, lateral tooth, lateral (F1) and labial (F2) view. G. Rhinoptera cf. R. studeri (Agassiz, 1843), BCGM 9123, occlusal (G1) and lingual (G2) view. H. Gymnura sp., BCGM 9107, lateral (H1) and labial (H2) view.