Pseudaetobatus undulatus, CICIMURRI AND EBERSOLE, 2015

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 : 19

PSEUDAETOBATUS UNDULATUS CICIMURRI AND EBERSOLE, 2015

( FIG. 7F–I )

Referred specimens —SC96.97.52, 22 medial tooth fragments; SC96.97.53, lateral tooth; SC 2001.1.3, 118 partial medial teeth; SC 2001.1.4, three lateral teeth; SC 2001.1.5, 10 lateral teeth; SC 2001.1.6, lateral tooth; SC 2001.1.7, lateral tooth; SC2013.38.84, lower medial tooth; SC2013.38.85, upper medial tooth; SC2013.38.86, upper medial tooth; SC2013.38.87, upper medial tooth; SC2013.38.88, incomplete upper medial tooth; SC2013.38.89, incomplete upper medial tooth; SC2013.38.90, lower medial tooth; SC2013.38.91, lower distal-most lateral tooth; SC2013.38.92, upper distal-most lateral tooth; SC2013.38.93, five lower distal-most laterals; SC2013.38.94, 12 upper distal-most lateral teeth; SC2013.38.95, lateral tooth; SC2013.38.96, five lateral teeth; SC2013.38.97, 87 incomplete medial teeth.

Remarks —We assign 275 teeth in our sample to Pseudaetobatus . Upper median teeth of Pseudaetobatus are wide and straight ( Fig. 7F ), whereas median teeth from the lower dental battery are more arcuate ( Fig. 7G ). Median teeth are easily distinguished from those of Aetomylaeus (see above) in that the labial and lingual crown faces are only weakly ornamented (as opposed to heavily pitted labially and with granular texture lingually) and the lingual ridge at the crown/root junction is thick and rounded instead of thin and sharp. These features can also be used to distinguish the lateral teeth of both species, and the distal-most lateral teeth of Pseudaetobatus are also sinuous ( Fig. 7I ).

Pseudaetobatus has only recently been formally reported from the United States, with two new species described by Cicimurri and Ebersole (2015). Pseudaetobatus belli Cicimurri and Ebersole, 2015 is an early Eocene species that occurs in Mississippi and Alabama, whereas Ps. undulatus is thus far only known from the upper Eocene Dry Branch Formation of South Carolina.

Figures

Figure 7. Myliobatidae teeth from the Dry Branch Formation (Priabonian) of Aiken County, South Carolina. A–E. Aetomylaeus sp. Incomplete lower median tooth in labial (A), lingual (B), and occlusal (C) and views, SC2001.1.2. Lateral tooth in occlusal (D) and profile (E) views, SC2001.1.29. F–I. Pseudaetobatus undulatus. Upper median tooth in occlusal (F) view, SC2013.38.86. Lower median tooth in occlusal (G) view, SC2013.38.84. Upper right distal-most lateral tooth in occlusal (H) and labial (I) views, SC2013.38.91. Lateral tooth in occlusal (J) view, SC2013.38.96.2. K–R. Rhinoptera sp. Lateral tooth in labial (K), lingual (L), occlusal (M), and basal (N) views, SC2001.1.12. Median tooth in occlusal (O), lingual (P), and basal (Q) views, SC2001.1.16. Lateral tooth in lingual (R) view, SC2013.38.70. Labial at top in C, D, F–H, J, M–O, Q; at right in E. Scale bars=1 cm in A–C, F–I, K–R; 5 mm in D, E, J.