Scoliodon conecuhensis Cappetta & Case, 2016

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 : 80-82

Scoliodon conecuhensis Cappetta & Case, 2016

Fig. 29

Scoliodon conecuhensis Cappetta & Case, 2016: 59 , pl. 9, figs 1–6.

Material examined

UNITED STATES OF AMERICA – Alabama • 130 isolated teeth; Claiborne Group ; ALMNH PV1993.2.440b (2 specimens), ALMNH PV1993.3.408 (2 specimens), GSA-V702, MSC 188.130 , MSC 188.268 , MSC 188.323 , MSC 2175.17 , MSC 2175.38 , MSC 2394.2 – 5 , MSC 34405.14 , MSC 34405.2 , MSC 37133, MSC 37316.1 – 4 , MSC 37326.1 – 3 , MSC 37627, MSC 37672, MSC 37678.1 – 7 , MSC 37753.1 – 8 , MSC 37754, MSC 37755, MSC 37756.1 – 19 , MSC 37757.1 – 2 , MSC 37758.1 – 2 , MSC 37759.1 – 2 , MSC 37760, MSC 37761.1 – 5 , MSC 37762, MSC 38490.1 – 5 , MSC 38498.1 – 3 , MSC 38523.1 – 2 , MSC 38553.1 – 4 , NJSM 24028 , SC 2012.47.170 (4 specimens), SC 2012.47.247 (2 specimens), SC 2012.47.249 (4 specimens), SC 2012.47.69 (4 specimens), WSU 5028 (4 specimens), WSU 5038 (10 specimens), WSU 5045 (9 specimens), WSU CC 530.2 (2 specimens), WSU CC 553 .

Description

Anterior teeth taller than wide, lateral teeth wider than tall. Teeth with narrow, elongate, triangular, sharply distally inclined crown. Lingual crown face strongly convex; labial face weakly convex; enameloid smooth. Cusp apex with slight lingual flexure; apex extends nearly to, or slightly beyond, distal edge of crown. Mesial cutting edge elongate, smooth, straight, sinuous or convex; straighter on lower teeth. Distal cutting edge short, smooth, oblique. Short, smooth distal heel on all lateral teeth; heel lacking on some anterior teeth. Root very low, bilobate, with highly diverging lobes. Interlobe area lacking to weakly U-shaped. Conspicuous lingual root boss bears narrow, deep nutritive groove.

Remarks

Scoliodon conecuhensis was named by Cappetta & Case (2016) for a series of teeth collected from site ACov- 11 in Covington County, AL. The teeth of S. conecuhensis are morphologically similar to those of Physogaleus and Rhizoprionodon . However, Scoliodon teeth are easily distinguished from Physogaleus by their lack of denticulations on the mesial cutting edge and distal heel. They were separated from Rhizoprionodon by having a narrower and more elongated cusp that extends to, or beyond, the distal edge of the crown.

The extant Scoliodon laticaudus Müller & Henle, 1838 , and some species of Rhizoprionodon , exhibit gynandric heterodonty. The extinct species S. conecuhensis also appears to have displayed a strong degree of gynandric heterodonty. Male teeth have a cusp that is mesiodistally thinner than those on female teeth, and male upper teeth have a more sinuous crown than do female teeth. In addition, male lower lateral teeth have a shorter, upturned cusp. Also, male lower lateral teeth have an elongated mesial heel, but the heel is very short or absent altogether on anterior teeth. The cusp on S. conecuhensis anterior teeth have a lingually twisted apex, which is lacking on equivalent teeth of Rhizoprionodon ganntourensis .

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the lower Tallahatta Formation at site ADl-1, the contact of the Tallahatta and Lisbon formations at site ACh-14 and ACov-11, the basal Lisbon Formation at site ACov-11, the contact of the Lisbon Formation and Gosport Sand at site AMo-4, the basal Gosport Sand at site ACl-4, and the Gosport Sand at sites ACh-21 and ACl-15. Upper Ypresian to middle Bartonian, zones NP14 to NP17.

Figures

Fig. 29. Scoliodon conecuhensis Cappetta & Case, 2016, teeth. A–C. MSC 188.130, upper lateral tooth, basal Gosport Sand. A. Labial view. B. Lingual view. C. Mesial view. D–F. MSC 38498.1, upper lateral tooth, basal Gosport Sand. D. Labial view. E. Lingual view. F. Mesial view. G–I. MSC 188.268, lower lateral tooth, basal Gosport Sand. G. Labial view. H. Lingual view. I. Mesial view. J–L. MSC 37627, upper lateral tooth, basal Lisbon Formation. J. Labial view. K. Lingual view. L. Mesial view. M–O. MSC 34405.2, lower lateral tooth, lower Tallahatta Formation. M. Labial view. N. Lingual view. O. Mesial view. P–R. MSC 37756.1, lateral tooth, lower Tallahatta Formation. P. Labial view. Q. Lingual view. R. Mesial view. S–U. MSC 37133, upper anterolateral tooth, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan. S. Labial view. T. Lingual view. U. Mesial view. V–X. MSC 38490.3, upper lateral tooth, basal Lisbon Formation. V. Labial view. W. Lingual view. X. Mesial view. Y–AA. MSC 38490.2, lower lateral tooth, basal Lisbon Formation. Y. Labial view. Z. Lingual view. AA. Mesial view. BB–DD. MSC 38498.3, upper lateral tooth, basal Gosport Sand. BB. Labial view. CC. Lingual view. DD. Mesial view. EE–GG. MSC 37678.1, male lower anterior tooth, basal Lisbon Formation. EE. Labial view. FF. Lingual view. GG. Mesial view. HH–JJ. MSC 37756.3, male lower anterior tooth, lower Tallahatta Formation. HH. Labial view. II. Lingual view. JJ. Mesial view. KK–MM. MSC 37756.2, male lower anterior tooth, lower Tallahatta Formation. KK. Labial view. LL. Lingual view. MM. Mesial view. Scale bars for A–F, M–X, BB–DD, KK–MM = 5 mm. Scale bars for G–L, Y–AA, EE–JJ =2 mm.