Scylliorhinus undetermined

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 : 16

SCYLLIORHINUS SP.

( FIG. 5O –CC)

Referred specimens —SC2001.1.42, incomplete tooth; SC2013.38.35, tooth; SC2013.38.36, tooth; SC2013.38.37, tooth; SC2013.38.38, tooth; SC2013.38.39, tooth; SC2013.38.40, tooth; SC2013.38.160, anterior tooth.

Remarks —Unfortunately, our eight teeth lack enameloid and/or have broken cusps, and the true height of the main cusp and lateral cusplets cannot be determined. Teeth are distinctive in that the labial crown foot is highly concave so that two lobes, a short mesial and a more elongated distal lobe, are developed. One or two cusplets are found on the mesial lobe, but only one large cusplet occurs on the distal lobe. The specimens exhibit crown ornamentation and lateral cusplets, and they are of similar size to other scyliorhinid teeth in our sample that we identify as Premontreia (see above). However, the root morphology and strongly asymmetrical nature of the crown are not typical of species within the genus Premontreia (Noubhani and Cappetta 1997, Malyshkina 2006, Mollen 2008).

The discontinuous nature of the nutritive groove on our teeth is consistent with the morphology of Scyliorhinus species identified elsewhere (Noubhani and Cappetta 1997). The preservation of the Dry Branch teeth inhibits our ability to compare them to known species, but in terms of overall morphology they are similar to Paleocene Sc. entomodon Noubhani and Cappetta, 1997 of Morocco and Sc. joleaudi Cappetta, 1970 from the lower Miocene of France. However, the Dry Branch teeth differ from the Moroccan species in that the crown lobes are much more widely separated, and all specimens exhibit enameloid ornamentation (Noubhani and Cappetta 1997). The main cusp of Sc. joleaudi appears to have been larger than the Dry Branch taxon, the crown lobes are closer together, and cusplets are also larger ( Cappetta 1970). A larger sample size and more complete material will help with making a more specific determination.

Figures

Figure 5. Scyliorhinid shark teeth from the Dry Branch Formation (Priabonian) of Aiken County, South Carolina. A–G. Foumtizia sp. Anterior tooth in labial (A), lingual (B) and profile (C) views, SC2013.38. 27. Anterior tooth in labial (D) view, SC96.97.5. Anterior tooth in labial (E) view, SC96.97.6. Anterior tooth in labial view (F), SC96.97.7. Anterior tooth in labial view (G), SC 96.97.8. H–N. Premontreia (Oxyscyllium) sp. cf. Pr. (O.) gilberti. Anterior tooth in labial (H) and distal (I) views, SC2013.38.29. Labial at left in I. Anterior? tooth in labial (J), lingual (K) and basal (L) views, SC2013.38.30. Lateral tooth in labial (M) and lingual (N) views, SC2013.38.31. O–CC. Scyliorhinus sp. Lateral tooth in labial (O), lingual (P), occlusal (Q), and basal (R) views, SC2013.38.36. An- terolateral tooth in basal (S) view, SC2013.38.35. Lateral tooth in labial (T), lingual (U), and occlusal (V) views, SC2013.38.39. Lateral tooth in labial (W), lingual (X), and occlusal (Y) views, SC2013.38.37. Lateral tooth in labial (Z), lingual (AA), and occlusal (BB) views, SC2013.38.38. Anterior? tooth in occlusal (CC) view, SC2013.38.40. Labial at top in L, R, S; at bottom in Q, V, Y, BB, CC. Scale bars=1mm.