Abdounia enniskilleni ( White, 1956 )

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 : 84-86

Abdounia enniskilleni ( White, 1956)

Fig. 31 A–O

Scyliorhinus enniskilleni White, 1956: 128 , pl. 11, fig. 1, text-figs 1–9.

Abdounia enniskilleni – Cappetta 1980a: 37 .

Scyliorhinus enniskilleni – Thurmond & Jones 1981: 60 , fig. 26.

Material examined

UNITED STATES OF AMERICA – Alabama • 302 isolated teeth; Claiborne Group ; ALMNH PV1989.4.16.2a (6 specimens), ALMNH PV1989.4.23.7, ALMNH PV1989.4.32.2 (2 specimens), ALMNH PV1989.4.38.3, ALMNH PV1989.4.126c, ALMNH PV1989.4.192, ALMNH PV1989.4.194 (2 specimens), ALMNH PV1989.4.205, ALMNH PV1989.4.209 (seven specimens), ALMNH PV1989.4.210, ALMNH PV1993.2.440a (56 specimens), ALMNH PV2000.1.43.2b, ALMNH PV2000.1.43.5e (2 specimens), ANSP 23416 , MSC 188.23 , MSC 188.50 , MSC 188.94 , MSC 188.112 .1, MSC 188.129 , MSC 188.159 , MSC 188.164 , MSC 188.169 , MSC 188.174 , MSC 188.204 , MSC 188.233 , MSC 188.262 – 263 , MSC 188.278 , MSC 188.282 – 283 , MSC 188.292 , MSC 188.307 , MSC 188.310 – 311 , MSC 188.317 – 318 , MSC 188.330 – 331 , MSC 567 , MSC 1424.2 , MSC 1424.11 , MSC 2171.1 – 6 , MSC 2171.8 – 13 , MSC 2175.49 , MSC 2175.64 , MSC 2175.70 , MSC 2175.75 – 76 , MSC 2372.5 , MSC 2372.13 , MSC 2384.1 – 2 , MSC 12675.5 – 11 , MSC 12686, MSC 36965, MSC 37405.1 – 2 , MSC 37453, MSC 37513, MSC 37567.106 , MSC 37568.1 – 4 , MSC 37569, MSC 37608, MSC 37620, MSC 37696, MSC 37890.1 – 2 , MSC 38412.1 – 2 , MSC 38497.1 – 6 , MSC 38507.1 – 14 , MSC 38533.1 – 4 , MSC 38550.1 – 8 , NJSM 24026 , WSU CC 538 (4 specimens) .

Description

Anterior teeth with tall, erect main cusp. Lingual crown face convex, often with fine longitudinal ridges extending more than half the cusp height. Labial crown face flat, smooth. Single pair of diverging lateral cusplets. Lateral teeth with broader but lower main cusp; cusp distally inclined. Single pair of divergent lateral cusplets; broader and lower than on anterior teeth. Lateroposterior teeth with more distally curving main cusp. Cutting edges of main cusp and lateral cusplets smooth, continuous. Root high, bilobate with short, rounded, diverging lobes. Lingual attachment surface flat; wide and deep nutritive groove. Interlobe area on teeth shallow and U-shaped.

Remarks

Teeth of A. enniskilleni were differentiated from the other Abdounia species in our sample by having a single pair of divergent cusplets in all tooth positions, and the lingual face of the main cusp generally bears fine lingual ornamentation. Additionally, this species is the largest of those we assign to Abdounia , with anterior teeth reaching upwards of 1.5 cm in overall height. Based on our sample of teeth, and several thousand more from the Clinchfield Formation of central Georgia, the teeth of A. enniskilleni appear extremely variable. For example, not all teeth exhibit lingual ornamentation, the main cusp within various files vary in width, and the lateral cusplets, especially in anterior positions, range from tall and narrow to low and wide. Abdounia enniskilleni is easily distinguished from two species formerly placed within Abdounia (see below), A. recticona and A. claibornensis , by the presence of a single pair of lateral cusplets, as opposed to three-to-four and four-to-eight, respectively, in the latter two taxa.

Stratigraphic and geographic range in Alabama

The specimens we examined were collected from the contact of the Tallahatta and Lisbon formations at sites ACh-14 and ACon-6, the basal Lisbon Formation at site ACov-11, the “upper” Lisbon Formation at sites ACh-8 and ACl-3, basal Gosport Sand at site ACl-4, and the Gosport Sand at sites ACh-21 and ACl-15. Lower Lutetian to middle Bartonian, zones NP14 to NP17.

Figures

Fig. 31. Abdounia enniskilleni (White, 1956) and A. minutissima (Winkler, 1874), teeth. A–O. A. enniskilleni. A–C. MSC 2171.8, anterior tooth, basal Gosport Sand. A. Labial view. B. Lingual view. C. Mesial view. D–F. MSC 37620, anterior tooth, “upper” Lisbon Formation, courtesy of James Lowery. D. Labial view. E. Lingual view. F. Mesial view. G–I. MSC 37567.1, anterior tooth, basal Gosport Sand. G. Labial view. H. Lingual view. I. Mesial view. J–L. MSC 1424.2, lateral tooth, basal Gosport Sand. J. Labial view. K. Lingual view. L. Mesial view. M–O. MSC 188.292, lateral tooth, basal Gosport Sand. M. Labial view. N. Lingual view. O. Mesial view. — P–GG. A. minutissima. P–R. MSC 35768.2, lateral tooth, lower Tallahatta Formation. P. Labial view. Q. Lingual view. R. Mesial view. S–U. MSC 35768.1, anterior tooth, lower Tallahatta Formation. S. Labial view. T. Lingual view. U. Distal view. V–X. MSC 37574.1, lateral tooth, basal Gosport Sand. V. Labial view. W. Lingual view. X. Mesial view. Y–AA. MSC 37574.2, anterior tooth, basal Gosport Sand. Y. Labial view. Z. Lingual view. AA. Distal view. BB–DD. MSC 37577.1, anterior tooth, basal Lisbon Formation. BB. Labial view. CC. Lingual view. DD. Mesial view. EE–GG. MSC 37577.2, anterior tooth, basal Lisbon Formation. EE. Labial view. FF. Lingual view. GG. Mesial view. Scale bars: A–O=5 mm; P–GG =2 mm.