Notorynchus 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 : 4

NOTORYNCHUS SP. Cf. NO. KEMPI WARD, 1979A

( FIG. 2A–D )

Referred specimens —SC96.97.4, incomplete lower right tooth; SC2001.1.46, lower tooth fragment; SC2013.38.1, incomplete lower left tooth.

Remarks —The incompleteness of the three specimens inhibits our ability to accurately identify the Dry Branch hexanchid. However, when compared to taxa identified from Eocene deposits elsewhere, we found that the acrocone mesial cusplets of SC96.97.4 ( Fig. 2C–D ) are more numerous but much smaller than those of Notidanodon Cappetta, 1975 , and the distal cusplets of SC2013.38.1 ( Fig. 2A, B ) also conspicuously diminish in size away from the acrocone ( Gurr 1962, Casier 1967, Ward 1979a). Lower teeth of Hexanchus agassizi Cappetta, 1976 are smaller and have 7–12 distal cusplets, as opposed to less than six on the Dry Branch taxon ( Cappetta 1976, Ward 1979a). In overall morphology, our material compares favorably to lower teeth of Notorynchus , particularly No. serratissimus ( Agassiz, 1843) and No. kempi . Early to middle Eocene teeth of No. serratissimus have a smaller crown (less than 17 mm width), fewer distal cusplets,and mesial serrations on the acrocone increase in size apically ( Cappetta1976, Ward 1979a, Nolf 1988, Van den Eekhaut and De Schutter 2009). In contrast, middle to late Eocene No. kempi teeth are larger than the aforementioned taxon (greater than 30 mm width) and the mesial serrations are large and of relatively uniform size (Ward 1979a). The Dry Branch hexanchid appears to have been as large as No. kempi and the evenness of the acrocone serrations on SC96.97.4 ( Fig. 2C, D ) is also consistent with this species.

Figures

Figure 2. Shark teeth from the Dry Branch Formation (Priabonian) of Aiken County, South Carolina. A–D. Notorynchus sp. cf. No. kempi teeth. Lower left tooth in lingual (A) and labial (B) views, SC2013.38.1. Lower right tooth in labial (C) and lingual (D) views, SC96.97.4. E. Squatina sp. cf. Sq. prima. Antero-lateral tooth in labial view, SC96.97.9. F,G. Nebrius sp. cf. Neb. thielensi. Anterolateral tooth in labial (F) and occlusal (G) views, SC2013.38.5. Labial at top in G. H. Ginglymostomatidae. Tooth in labial view, SC2013.38.7. I–O. Carcharias sp. Third lower right anterior tooth in labial (I) view, SC2001.1.55. Third upper right anterior tooth in lingual (J) and labial (K) views, SC2001.1.57. First lower right anterior tooth in labial (L) view, SC2001.1.59. Second lower right anterior tooth in labial (M) view, SC96.97.44.1. Second upper right anterior tooth in lingual (N) view, SC96.97.42. Lower left lateral tooth in lingual (O) view, SC96.97.43. P–S. Alopias sp. Tooth in labial (P) and lingual (Q) views, SC2001.1.65. Tooth in labial (R) and lingual (S) views, SC2001.1.66. Scale bars=1 cm in A–D, I–K, N, O; 5 mm in E–G, L–M, P–S; 1 mm in H.