Anisotremus? sp, Gill, 1861

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, inclu, European Journal of Taxonomy 585, pp. 1-274: 211-212

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Anisotremus? sp


Anisotremus? sp  .

Fig. 71View Fig K–L

Anisotremus  sp. – Nolf & Stringer 2003: 6, pl. 5, figs 13a–b.

Material examined

UNITED STATES OF AMERICA – Alabama • 2 otoliths; GLS otolith comparative collection (1 specimen), MSC MSC 42236View Materials  .


Specimens quite large; one broken specimen measures approximately 20 mm long, 12 mm wide; more complete specimen 16 mm long. Shape primarily ovate, with posterior having greater width. Height/ length ratios around 65%. Margins smooth except for dorsal margin. Anterior margin short, consisting primarily of ostium opening. Anterodorsal margin fairly straight, slants upward. Dorsal margin continues slanting upward, characterized by four sharp crenulations. Posterodorsal margin straight to slightly incurved. Posterior margin short, rounded. Posteroventral margin slightly arched, slants fairly sharply to ventral margin. Ventral margin and posteroventral margin rounded, gently inclined upward to anterior margin. Inner face convex, marked by very large, prominent sulcus. Sulcus (heterosulcoid-type) located slightly more dorsally, extends from anterior margin almost to posteroventral margin (at least 95% of the length). Sulcus unevenly excavated, filled with colliculum. Ostium quite elongated, about same length as cauda. Dorsal and ventral margins of ostium approximately parallel except for very slight arching near cauda. Cauda narrow (about 85% of width of ostium). Horizontal portion of cauda slightly longer than downturned portion. Downturned portion of cauda forms approximately 45-degree angle. Cauda noticeably more excavated than ostium, with downturned portion of cauda being most excavated. Fairly deep, somewhat rectangular depressed area above horizontal portion of cauda. Downturned portion of cauda almost reaches posteroventral margin. Outer face irregularly concave, smoothly sculptured.


The Alabama Claibornian otoliths share many morphological features with Recent species of Anisotremus  , particularly A. caesius  . The specimens of Anisotremus  ? sp. from the Lisbon Formation of Alabama are similar to the Anisotremus  sp. described by Nolf & Stringer (2003) from the Eocene of Louisiana, but the Louisiana otoliths have a shorter downturned portion of the cauda.

Stratigraphic and geographic range in Alabama

The two specimens of Anisotremus  ? were recovered from the “upper” Lisbon Formation at site ACh-8. Bartonian, zones NP16 and NP17.














Anisotremus? sp

Ebersole, Jun A., Cicimurri, David J. & Stringer, Gary L. 2019


Nolf D. & Stringer G. 2003: 6