Premontreia (Oxyscyllium) subulidens ( Arambourg, 1952 )

Ebersole, Jun A., Cicimurri, David J. & Stringer, Gary L., 2019, Taxonomy and biostratigraphy of the elasmobranchs and bony fishes (Chondrichthyes and Osteichthyes) of the lower-to-middle Eocene (Ypresian to Bartonian) Claiborne Group in Alabama, USA, including an analysis of otoliths, European Journal of Taxonomy 585, pp. 1-274 : 58-59

Premontreia (Oxyscyllium) subulidens ( Arambourg, 1952)

Fig. 21

Scyliorhinus subulidens Arambourg 1952: 121 , figs 5–19.

Premontreia (Oxyscyllium) subulidens – Noubhani & Cappetta 1997: 55 , pl. 21:1–11.

Scyliorhinus sp. – Maisch et al. 2014: 192, fig. 3:17–19.

Material examined

UNITED STATES OF AMERICA – Alabama • 1 isolated tooth; Claiborne Group ; ANSP 23421 .

Description

Small tooth measuring 5.0 mm in total height as preserved. Main cusp narrow, triangular, sharply tapering apically. Labial face flat and smooth, whereas lingual face very convex, smooth. Smooth cutting edges reach base of cusp. Single pair of broad and triangular lateral cusplets that are diverging. Root with very short, reniform lobes that are bisected by deep and elongate nutritive groove. Basal attachment surface flat with heart-shaped outline.

Remarks

The single specimen in our sample, ANSP 23421, was derived from the Tallahatta/ Lisbon contact zone and was previously reported by Maisch et al. (2014). Although the authors indicated that the tooth was comparable to Premontreia , they ultimately identified it as Scyliorhinus sp. We reexamined the specimen and believe that it is Premontreia and can be referred to the subspecies Oxyscyllium due to the large size of the lateral cusplets. ANSP 23421 is virtually identical in size and morphology to specimens of P. (O.) subulidens illustrated by Arambourg (1952) and Noubhani & Cappetta (1997: pl. 21, 5), and we therefore attribute the specimen to this species.

Among the thousands of Claibornian specimens we personally examined, ANSP 23421 is the only tooth that can be identified as Premontreia . However, a second specimen reported by Cappetta & Case (2016: pl. 9, fig. 11) was identified by them as Premontreia (Premontreia) degremonti based on the diminutive size of the lateral cusplets. We could only examine the specimen via publication, but t he morphology is consistent with the species as described and illustrated by Cappetta (1992), although the tooth does appear to be ablated. It would appear to be serendipitous that two species of Premontreia are represented in a total sample size of two teeth from the Tallahatta/ Lisbon contact zone, and additional specimens are needed to corroborate these identifications.

Stratigraphic and geographic range in Alabama

ANSP 23421 was collected from the contact of the Tallahatta and Lisbon formations at site ACon-6. Cappetta & Case (2016) reported a specimen from the contact of the Tallahatta and Lisbon formations at site ACov-11 that they referred to Premontreia (Premontreia) degremonti . Lower Lutetian, zones NP 14 and NP15.

Figures

Fig. 21. Premontreia (Oxyscyllium) subulidens (Arambourg, 1952), tooth. A–D. ANSP 23421, lateral tooth, Tallahatta/Lisbon contact zone. A. Labial view. B. Lingual view. C. Mesial view. D. Basal view. Scale bar = 2 mm.