Hemipristis serra (Agassiz, 1835)

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 : 634

Hemipristis serra (Agassiz, 1835)

Fig. 5I, J .

Referred specimens.—BCGM 9071–9073, SC 2009.18.10.

Comments.—Dignathic heterodonty is strongly developed in the dentition of Hemipristis serra , with broad, recurved, very coarsely serrated upper teeth ( Fig. 5I ) and narrower lower lateral teeth. The largest upper lateral tooth is damaged but measures 18 mm in crown height. The crown of the largest complete upper lateral tooth measures 13 mm in height and 10.5 mm in width. The cutting edges of adult lower anterior teeth are poorly developed, with a few serrations located only at the crown foot. We see no appreciable difference between the Chandler Bridge sample and teeth we have personally observed from Mio−Pliocene deposits of South Carolina, North Carolina, Maryland, and Florida.

Adnet et al. (2007) hypothesized that specimens they identified as Hemipristis cf. H. serra (Rupelian of Pakistan) represented a transitional species between H. curvatus Dames, 1883 and H. serra , indicating a direct ancestor−descendant relationship between these taxa. Interestingly, Thomas et al. (1989) tentatively identified both of these species in Rupelian strata of Oman. We recovered several small (4 mm in basal width) upper teeth that lack serrations on the mesial cutting edge ( Fig. 5J ), identical to specimens Case (1980) identified as H. wyattdurhami White, 1956 (= H. curvatus ), and we consider these to represent juvenile H. serra (see also Chandler et al. 2006). These data provide strong evidence that H. serra evolved directly from H. curvatus (see also Adnet et al. 2007). Based on histological differences with extant H. elongata (Klunzinger, 1871) , Ward and Bonavia (2001) suggested that generic reassignment of the “ H. serra ” morphology is warranted.

Stratigraphic and geographic range.—Oligocene to Pliocene, Africa, Europe, USA, Java, India, Japan.

Figures

Fig. 5. Carcharhiniform sharks from Summerville, upper Chattian. A–D. Carharhinus gibbesi (Woodward, 1889). A. BCGM 9059, juvenile upper anterior tooth, labial view. B. BCGM 9060, adult upper anterior tooth, labial view. C. BCGM 9061, juvenile upper lateral tooth, labial view. D. BCGM 9058, adult lower anterior tooth, labial view. E, F. Physogaleus aduncus (Agassiz, 1835). E. BCGM 9064, upper lateral tooth, labial view. F. BCGM 9066, lower anterior tooth, labial view. G. Physogaleus sp., BCGM 9068, antero−lateral tooth, labial view. H. Rhizoprionodon sp., BCGM 9070, labial view. I, J. Hemipristis serra (Agassiz, 1835). I. BCGM 9073, adult upper lateral tooth, labial view. J. BCGM 9072, juvenile upper lateral tooth, labial view. K. Sphyrna cf. S. media Springer, 1940, BCGM 9077, lateral tooth, labial view. L. Sphyrna zygaena (Linneaus, 1758), BCGM 9079, lateral tooth, lingual view. M. Bythaelurus sp., BCGM 9074, labial view. N–P. Galeorhinus sp. N. BCGM 9081, parasymphyseal tooth, labial view. O. BCGM 9082, antero−lateral tooth, labial view. P. BCGM 9083, lateral tooth, labial view.