Carcharhinus gibbesii (Woodward, 1889)

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 : 9

CARCHARHINUS GIBBESII ( WOODWARD, 1889)

FIG. 5B, C

a trend towards increased tooth size in H. serra from the Oligocene to the Pliocene. Although imperfectly preserved, the Ashley Formation specimens are larger than any specimens of Eocene H. curvatus known to us from the Southeastern United States, and they also bear more serrations on the cutting edges, particularly on the mesial side ( Cicimurri and Knight 2019, Ebersole et al. 2019, DJC unpublished data Tupelo Bay Formation).

Type species — Carcharias melanopterus Quoy and

Gaimard, 1824; Recent

2009a Carcharhinus gibbesi ; Cicimurri and Knight, p. 632, fig. 5A–D.

Referred specimens (n=92) —SC2007.36.10, SC2007.36.11, SC2007.36.12 (ten teeth), SC2007.36.13 (32 teeth), SC2007.36.14 ( Fig. 5B ), SC2007.36.15 ( Fig. 5C ), SC2007.36.16 (25 teeth), SC2007.36.58, SC2007.36.59 (14 teeth), SC2015.29.21, SC2015.29.22, SC2015.29.23 (2 teeth), SC2015.29.24, SC2015.29.25.

Remarks —As was the case in the Chattian Chandler Bridge Formation assemblage described by Cicimurri and Knight (2009a), Carcharhinus gibbesii is the most common shark in our limited Ashley Formation sample. Müller (1999) identified C. elongatus ( Leriche, 1910) in the Ashley Formation and the Old Church Formation of Virginia, and he reported C. gibbesii as occurring in the Belgrade Formation of North Carolina and questionably within the Ashley Formation. Specimens we examined from both the Ashley and Chandler Bridge formations revealed that serration size and density varies, and C. gibbesii upper teeth have lateral heels that are more regularly and more coarsely serrated than those of C. elongatus from the European Oligocene (i.e., Baut and Génault 1999, Reinecke et al. 2001, Reinecke et al. 2005). The material Müller (1999) illustrated as C.elongatus (pl. 6, particularly figs. 7–8) exhibit rather coarsely serrated lateral shoulders, and we associate them with C. gibbesii rather than C.elongatus . Unfortunately, Müller (1999) did not illustrate the Ashley Formation teeth he questionably assigned to C. gibbesii , so direct comparisons to our sample cannot be made. Carcharhinus gibbesii appears to have been distributed on both sides of the Oligocene Atlantic Ocean, as the species has been documented from Chattian strata of Germany ( Reinecke et al. 2014).

Figures

Figure 5. Selachian teeth from the Givhans Ferry Member, Ashley Formation (Rupelian), Dorchester County, South Carolina. A. Hemipristis cf. H. serra tooth, SC2007.36.7 in labial view. B. Carcharhinus gibbesi upper tooth, SC2007.36.14 in labial view. C. Carcharhinus gibbesi lower tooth, SC2007.36.15 in labial view. D. Physogaleus cf. P. contortus tooth, SC2007.36.19 in labial view. E. Physogaleus sp. tooth, SC2007.36.21 in labial view. F. Galeocerdo aduncus tooth, SC2007.36.17 in labial view. G. Sphyrnidae Morphotype 1 tooth, SC2007.36.26 in labial view. H. Sphyrnidae Morphotype 2 tooth, SC2007.36.24 in labial view. Scale bar=3 mm in E; 5 mm in A, C, D, F, G; 10 mm in B.