Hemipristis undetermined

Cicimurri, David J. & Knight, James L., 2019, Late Eocene (Priabonian) elasmobranchs from the Dry Branch Formation (Barnwell Group) of Aiken County, South Carolina, USA, PaleoBios 36, pp. 1-31 : 14

HEMIPRISTIS SP. CF. H. CURVATUS DAMES, 1883

( FIG. 3M–P )

Referred specimens —SC96.97.33, upper lateral tooth; SC96.97.34, upper lateral tooth; SC96.97.35, lower lateral tooth; SC96.97.36, 13 incomplete teeth; SC 2001.1.20, incomplete upper tooth; SC 2001.1.21, upper tooth; SC 2001.1.22, five upper teeth; SC 2001.1.23, four incomplete teeth; SC2013.38.20, lower anterior tooth; SC2013.38.21, lower lateral tooth; SC2013.38.22, two juvenile upper tooth; SC2013.38.23, lower anterior tooth; SC2013.38.24, lower anterolateral tooth; SC2013.38.25, lower lateral tooth; SC2013.38.26, five incomplete upper teeth.

Remarks —Monognathic and dignathic heterodonty can be discerned within the sample of 39 teeth. Upper anterior teeth are narrow and rather erect, whereas lateral teeth are broadly triangular with a crown apex that is distinctively distally curved. The mesial edge of upper lateral teeth is completely smooth or weakly serrated on its basal half, but the distal edge is coarsely serrated nearly to the apex ( Fig. 3M ). Lower anterior teeth are comparatively narrower, erect, and serrations on cutting edges are restricted to the crown base ( Fig. 3P ).

Hemipristis teeth are distinctive in having very large cusplets along the distal crown edge, a characteristic evident even on teeth lacking enameloid ( Fig. 3N ). Hemipristis curvatus (identified as He. wyattdurhami White, 1956 in older literature) appears to have been widespread in the Eocene Atlantic and Gulf coastal regions, having been reported from North Carolina (Timmerman and Chandler 1995), Georgia ( Case 1981, Case and Borodin 2000, Parmley and Cicimurri 2003), Alabama (White 1956, Thurmond and Jones 1981), Louisiana (Manning and Standhardt 1986), and Arkansas (Westgate 1984). This taxon is easily separated from the temporally younger He. serra Agassiz, 1835 in that teeth are much smaller in size and the mesial cutting edges of lateral teeth are nearly or completely devoid of serrations.

Figures

Figure 3. Carcharhiniform shark teeth the Dry Branch Formation (Priabonian) of Aiken County, South Carolina. A–D. Physogaleus sp. cf. Ph. latus. Upper left lateral tooth in lingual (A) and labial (B) views, SC2013.38.65. Lower left anterior tooth in labial (C) and lingual (D) views, SC96.97.26. E, F. Galeocerdo sp. Anterolateral tooth in lingual (E) and labial (F) views, SC2013.38.16. G–I. Abdounia sp. cf. Ab. enniskilleni. Anterior tooth in lingual (G) and labial (H) views, SC96.97.30. Lateral tooth in lingual (I) view, SC96.97.31. J–L. Rhizoprionodon?ganntourensis. Anterolateral tooth in labial (J) and lingual (K) views, SC2013.38.98. Lateral tooth in lingual view (L), SC2013.38.99. M–P. Hemipristis sp. cf. He. curvatus. Upper left lateral tooth in lingual (M) and labial (N) views, SC2001.1.21. Lower right anterior tooth in lingual (O) and labial (P) views, SC2013.28.35. Q, R. Negaprion gilmorei. Upper right anterior tooth in lingual (Q) view, SC2013.38.61. Lower right anterolateral tooth in lingual (R) view, SC2013.38.64. Scale bars=1 cm in A–F, M–N, Q–R; 5 mm in G–L, O–P.