Ariosoma nonsector Nolf & Stringer, 2003

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 : 189-190

Ariosoma nonsector Nolf & Stringer, 2003

Fig. 69 G–H

Otolithus (Platessae) sector Koken, 1888: 292 , pl. 17, figs 5–16.

Ariosoma sp. – Stringer 1979: 102, pl. 1, fig. 4; 1986: 213, pl. 3, fig. 2.

Ariosoma nonsector – Nolf & Stringer 2003: 7 , pl. 2, figs 1a–6. — Nolf 2003: 3–4, pl. 1, figs 3–4; 2013: 35–37, pl. 21.

Material examined

UNITED STATES OF AMERICA – Alabama • 11 otoliths; GLS otolith comparative collection (10 specimens), MSC 39069 .

Description

Species characterized by massive otoliths; height nearly the same as the length, with height/length ratios ranging from 80–86%. Margins typically smooth. Ostial rim slightly concave, most specimens exhibiting some concavity at posterodorsal rim. Posterior margin tends to taper. Ventral rim broadly rounded, marked by distinctive angular central position. Inner face mainly smooth, convex, except for some irregular depressions in upper portion of dorsal area. Sulcus wide, only slightly incised. Sulcus extends from very near anterior margin to posterior (about 85% of sagitta length). Sulcus entirely filled with colliculum, except for dorsal extremity of ostial channel. No clear division of ostial and caudal portions of sulcus. Posterior end of sulcus broadly tapered but showing some widening ventrally. No indications of ventral furrow. Outer face smooth, convex except for area near posterior end, where shallow dorsoventrally oriented depression occurs.

Remarks

This species and Paraconger sector (see below) were originally described as one species by Koken (1888), but Ariosoma nonsector was separated by Nolf & Stringer (2003). This taxon is known from middle and upper Eocene deposits in Alabama, Louisiana, Mississippi, and Virginia in the USA, and it occurs in lower Oligocene (Rupelian) strata of Alabama, Louisiana, and Mississippi.

Stratigraphic and geographic range in Alabama

Ariosoma nonsector is known only from the “upper” Lisbon Formation at sites ACh-8 and ACl-4. The lack of A. nonsector in the Gosport Sand may be related to the very sandy nature of the formation or the lack of extensive bulk sampling. Bartonian, zones NP16 and NP17.

Figures

Fig. 69. Claiborne Group, “upper” Lisbon Formation, otoliths. A–B. Albula sp., MSC 562. A. Inner face (right sagitta). B. Dorsal view. — C–D. Pythonicthys colei (Müller, 1999), WSU CC 474. C. Inner face (left sagitta). D. Dorsal view. — E–F. Muraenesocidae Kaup, 1859, indet., MSC 39064. E. Inner face (left sagitta). F. Dorsal view. — G–H. Ariosoma nonsector Nolf & Stringer, 2003, MSC 39069. G. Inner face (left sagitta). H. Dorsal view. — I–J. Paraconger sector (Koken, 1888), MSC 39052. I. Inner face (right sagitta, broken on anterodorsal angle). J. Dorsal view. — K–L. Pseudophichthys sp., MSC 37059.2. K. Inner face (right sagitta). L. Dorsal view. — M–N. Rhynchoconger sp., MSC 37059.6. M. Inner face (left sagitta). N. Dorsal view. — O–P. Gnathophis meridies (Frizzell & Lamber, 1962), MSC 37059.XX. O. Inner face (right sagitta). P. Dorsal view. — Q–R. Myripristis sp., MSC 39047. Q. Inner face (right sagitta). R. Dorsal view. Scale bars: A–B =5 mm; C–R =2 mm.