Galeorhinus sp.

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 : 635

Galeorhinus sp.

Fig. 5N–P .

Referred specimens.—BCGM 9080–9083, SC 2009.18.13.

Comments.—These teeth can be distinguished from all other Chandler Bridge carcharhinids in that the labial crown foot is obviously thicker and clearly overhangs the root. Upper teeth of Chaenogaleus Gill, 1862 are distinguished from Galeorhinus Blainville, 1816 in having a labial crown foot that does not overhang the root ( Cappetta 1987). Heterodonty is developed in our sample; parasymphyseal teeth are nearly symmetrical ( Fig. 5N ) and anterior teeth have a rather erect cusp, elongated and smooth mesial cutting edge, and two to four large cusplets on the distal heel ( Fig. 5O ). Teeth become smaller and the cusp more distally inclined towards the commissure ( Fig. 5P ). A specimen identified by Case (1980: pl. 7: 3) as G. affinis (Probst, 1878) is more appropriately referred to Physogaleus , and an additional specimen identified as G. galeus (Linnaeus, 1758) (see Case 1980: pl. 7: 6) may best be left in open nomenclature. This latter specimen differs from our material in having five obvious distal cusplets as opposed to three or four. Although of similar size, the Chandler Bridge Galeorhinus differs from extant G. galeus in having fewer cusplets on the distal blade, a more convex mesial cutting edge, and nodular ornamentation on the labial crown foot (see also Herman et al. 1988). A specimen from the Oligocene of North Carolina assigned to G. aff. galeus by Müller (1999: pl. 5: 1) is comparable to the Chandler Bridge Galeorhinus . Material documented from the German Oligocene ( Galeorhinus sp. ) is similar to the Chandler Bridge teeth ( Reinecke et al. 2001, 2005).

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.