Dasyatis, SP., Rafinesque, 1810

Cicimurri, David J., Knight, James L. & Ebersole, Jun A., 2022, Early Oligocene (Rupelian) fishes (Chondrichthyes, Osteichthyes) from the Ashley Formation (Cooper Group) of South Carolina, USA, PaleoBios 39 (1), pp. 1-38 : 17

“ DASYATIS ” SP.

FIG. 7V –CC

Type species — Dasyatis ujo Rafinesque, 1810a ; Recent.

2009a Dasyatis rugosa ( Probst, 1877) ; Cicimurri and Knight, page 638, fig. 8C.

Referred specimens (n=11) —SC2007.36.49 ( Fig. 7V –CC1), SC2007.36.50 (three teeth), SC2007.36.51 ( Fig. 7T–U ), SC2007.36.225, SC2015.29.14, SC2015.29.43, SC2015.29.44, SC2015.29.45 ( Fig. 7V–Y ), SC2015.29.46.

Remarks —These teeth differ from those of “ Taeniurops ” cavernosus discussed above by having a more convex labial face, a more angular labial crown margin (as opposed to uniformly convex), and a wider transverse crest that is crenulated. The Ashley Formation specimens are ablated but appear to be conspecific with teeth occurring in the overlying Chandler Bridge Formation identified as Dasyatis rugosa ( Probst, 1877) by Cicimurri and Knight (2009a). Reinecke (2015) noted differences between the Chandler Bridge teeth and D. rugosa from Germany, and he indicated an early Chattian first appearance for this species. Reinecke et al. (2011) illustrated (plate 96, fig. 4) one of Probst’s (1877) original specimens of D. strangulata , and the species was also reported by Reinecke et al. (2014) and Reinecke and Radwański (2015). The South Carolina specimens do appear to have a more convex labial face with less robust ornamentation, and they are more similar to D. strangulata than to D. rugosa in these respects ( Reinecke et al. 2011, Reinecke et al. 2014, Reinecke and Radwański 2015).

Although teeth with this morphology have traditionally been placed within Dasyatis (see Cappetta 2012), recent molecular studies of extant species revealed the genus to be paraphyletic ( Last et al. 2016, Nelson et al. 2016). This prompted the referral of many extant Dasyatis species to various other genera, like Bathytoshia Whitley, 1933 , Fontitrygon Last et al., 2016 , Hemitrygon Müller and Henle, 1838 , Hypanus Rafinesque, 1818 , Megatrygon Last et al., 2016 , and Telatrygon Last et al., 2016 . Because a comparative study of the dentitions of these extant taxa has yet to be undertaken, we herein conservatively retain this species within Dasyatis with the understanding that they may someday be referred to one of the aforementioned extant genera, or perhaps to an unknown fossil taxon. The Ashley Formation specimens are morphologically similar to D. strangulata , a taxon that has tentatively been identified from the late Chattian by Reinecke et al. (2014). However, we refrain from assigning the South Carolina specimens to this species due to their much older occurrence compared to the typically Miocene range of D. strangulata .

Figures

Figure 7. Batoid teeth from the Givhans Ferry Member, Ashley Formation (Rupelian), Dorchester County, South Carolina. A, B. Raja mccollumi male tooth, SC2007.36.132 in distal (A) and labial (B) views. C, D. Raja mccollumi female tooth, SC2007.36.31 in mesial (C) and labial (D) views. E, F. Raja sp. male tooth, SC2007.36.33 in mesial (E) and labial (F) views. G, H. Raja mccollumi female tooth, SC2007.36.124 in mesial (G) and labial (H) views. I. Rhynchobatus sp. tooth, SC2007.36.39 in occlusal view. J–M. “Taeniurops” cavernosus low-crowned tooth, SC2015.29.42 in occlusal (J), profile (K), labial (L), and basal (M) views. N–Q. “Taeniurops” cavernosus male tooth, SC2015.29.2 in occlusal (N), profile (O), labial (P), and basal (Q) views. R, S. “Taeniurops” cavernosus low-crowned tooth, SC2007.36.53 in occlusal (R) and profile (S) views. T, U. “Taeniurops” cavernosus male tooth, SC207.36.51 in occlusal (T) and profile (U) views. V–Y. “Dasyatis” sp. low-crowned tooth, SC2015.29.45 in occlusal (V), profile(W), labial (X), and labio-oblique (Y) views. Z–CC. “Dasyatis” sp. low-crowned tooth, SC2007.36.49 in occlusal (Z), profile (AA), lingual (BB), and labial (CC) views. Scale bar=0.5 mm in C, D, G, H; 1 mm in E, F, I, T, U; 2 mm in A, B; 5 mm in J–S, V–CC.