Abdounia enniskilleni (White, 1956)

Cicimurri, David J. & Knight, James L., 2022, Late Eocene (Priabonian) elasmobranchs from the Dry Branch Formation (Barnwell Group) of Aiken County, South Carolina, USA, PaleoBios 36, pp. 1-31 : 10

ABDOUNIA ENNISKILLENI (WHITE, 1956)

( FIG. 3G–I )

Ref er red s p eci m ens —S C96.97.30, a n terior tooth; SC96.97.31, lateral tooth; SC96.97.32, 43 teeth; SC2001.1.43, anterior tooth; SC2001.1.44, three teeth; SC2013.38.15, incomplete tooth.

Remarks —Gradient monognathic heterodonty is evident among the 50 specimens we examined, with anterior teeth having tall vertical main cusps ( Fig. 3G, H ), but cusps becoming lower, broader, and distally curved ( Fig. 3I ) in lateral and posterior positions. Fine vertical enameloid ridges are preserved on specimens from the NAS, and this feature, combined with the gross morphology of teeth, leads us to assign them to Abdounia enniskilleni . This species has been reported from several upper Eocene localities in the Gulf and Atlantic coastal plains (often identified as Scyliorhinus enniskilleni prior to 1987), including Louisiana (Manning and Standhardt 1986), Arkansas (Westgate 1984), Alabama (White 1956), North Carolina (Timmerman and Chandler 1995), and Georgia ( Case 1981, Case and Borodin 2000, Parmley and Cicimurri 2003). Within the Dry Branch sample, Ab. enniskilleni can be differentiated from small odontaspidid teeth in that the lateral cusplets are large in relation to the main cusp, the lingual root face is flat, and root lobes are shorter and more triangular in outline.

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.