Ekokenia eporrecta Frizzell & Dante, 1965

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 : 217-218

Ekokenia eporrecta Frizzell & Dante, 1965

Fig. 72 E–F

Otolithus (Sciaenidarum) eporrectus Koken, 1888: 282 , pl. 18, figs 16–17.

Otolithus (Sciaenidarum) eporrectus – Posthumus 1924: 27 . — Campbell 1929a: 264, pl. 29, figs 16–17.

Ekokenia eporrecta – Frizzell & Dante 1965: 704 , pl. 87, figs 11–12, 16; pl. 88, figs 5, 11. — Schwarzhans 1993: 27, fig. 11.

“genus Sciaenidarum ” eporrectus – Breard & Stringer 1999: 135 . — Müller 1999: 160, pl. 33, figs 10–15.

“ Sciaenida ” eporrecta – Nolf 2013: 107 , pl. 281.

Material examined

UNITED STATES OF AMERICA – Alabama • 36 otoliths; GLS otolith comparative collection (33 specimens), MSC 7300 , MSC 39048, WSU CC 473.1 .

Description

Sagittae range from approximately oval (smaller specimens) to elliptical (larger specimens). Inner face fairly smooth, convex. Adult specimens fairly large, exceeding 10 mm in length. Height/length ratios range from approximately 62–74%. Margins irregularly smooth on adult specimens, can be finely crenulate on small specimens.Anterior margin slopes backwards on smaller specimens, nearly vertical on larger specimens. Dorsal margin irregular, dorsal dome usually present. Posterodorsal dome is present on many specimens. Posterior margin straight to slightly incurved. Ventral margin broadly, evenly rounded. Very prominent heterosulcoid-type sulcus occurs on inner face, extending from anterior margin almost to posteroventral margin. Sulcus excavated, posterior slightly flexed downward. Ostium about onehalf the length of cauda, twice as wide. Ostium filled with colliculum. Sides of ostium approximately parallel. Cauda narrow (one-half width of ostium), slightly flexed downward at posterior. Posterior of cauda pointed. Very prominent depressed area, nearly rectangular in shape, above sulcus. Crista superior well-developed, forms distinct raised ridge above cauda. Ventral furrow appears absent. Outer face concave; concavity increases with size. Outer face excavated on dorsal half. Irregular undulations common on the larger specimens.

Remarks

Koken (1888) first reported this taxon from Newton, Mississippi, and the formation from which it was found is now known to be the middle Eocene Cook Mountain Formation. The species also occurs in the Cook Mountain Formation of Texas (very common in the Stone City Member) and Louisiana, as well as the middle Eocene Piney Point Formation of Virginia.

Stratigraphic and geographic range in Alabama

This species is common in the “upper” Lisbon Formation at site ACh-8. Bartonian, zones NP16 and NP17.

Figures

Fig. 72. Claiborne Group, “upper” Lisbon Formation, otoliths. A–D. Jefitchia claybornensis Frizzell & Dante, 1965. A–B. MSC 39057. A. Inner face (right sagitta, juvenile). B. Dorsal view. C–D. MSC 39049. C. Inner face (right sagitta). D. Dorsal view. — E–F. Ekokenia eporrecta Frizzell & Dante, 1965, MSC 39048. E. Inner face (left sagitta). F. Dorsal view. Scale bars: A–D=2 mm; E–F=5 mm.