Dasyatis cavernosa (Probst, 1877)

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 : 637-638

Dasyatis cavernosa (Probst, 1877)

Fig. 8A, B .

Referred specimens.—BCGM 9096, 9097, and 9103, SC 2009.18.17.

Comments.—These teeth measure 2 mm in width and the majority are low−crowned. Labial ornamentation consists of large pits formed from highly irregular, interconnected ridges. The apical portion of the labial face is weakly concave, the transverse crest is sharp and distinct, and root lobes are rather gracile. Several male teeth are included in the sample, and these have higher crowns (more anterior teeth are highly cuspidate) and a concave labial face that is weakly ornamented with longitudinal ridges. The ornamentation of low−crowned teeth attributed to D. cavernosa is highly variable (see Leriche 1927: pl. 5: 20, 21, 24–28; Cappetta 1970; Case 1980; Bracher 2005; Müller 1999; Wienrich and Reinecke 2009). Teeth of D. cavernosa are comparable in size to D. delfortriei Cappetta, 1970 , but the crown ornamentation of the latter species has an appearance similar to a honeycomb structure (i.e., Cappetta 1970; Reinecke et al. 2005, 2008).

It has been shown that development of gynandric heterodonty in extant Dasyatis sabina (Lesueur, 1824) is related to mating behavior and not diet ( Kajiura and Tricas 1996). Male teeth of D. sabina are generally identical to those of females except during the mating season, when there is a transition to a high−crowned, cuspidate morphology that is used to grasp pectoral fins of females during copulation ( Kajiura et al. 2000). If we assume that this form of gynandric heterodonty applies to all species of Dasyatis Rafinesque, 1810 and that it was occurring during the Oligocene, the limited development of cuspidate teeth in males (see Fig. 8B ) could explain the high ratio (approximately 12:1) of low−crowned to high−crowned teeth in our sample.

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

Figures

Fig. 8. Stingrays from Summerville, upper Chattian. A. Dasyatis cavernosa (Probst,1877), BCGM 9097, occlusal (A1) and labial (A2) view. B. D. cf. cavernosa, BCGM 9103, male tooth, occlusal (B1) and labial (B2) view. C. D. rugosa (Probst, 1877), BCGM 9099, occlusal (C1) and labial (C2) view. D. Dasyatidae gen. et. sp. indet., BCGM 9101, occlusal (D1), labial (D2), and lateral (D3) view. E. BCGM 9106, Dasyatis sp. denticle, lateral−oblique view.