Signata nicoli 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 : 200

Signata nicoli Frizzell & Dante, 1965

Fig. 70 I–J

Signata nicoli Dante & Frizzell in Frizzell & Dante, 1965: 709 , pl. 88, figs 3–4, 21, 35.

“genus Ophidiidarum ” nicoli – Nolf 1980: 138 , pl. 20, fig. 7.

“ Ophidiida ” nicoli – Nolf 2013: 65 , pl. 124.

Material examined

UNITED STATES OF AMERICA – Alabama • 1 otolith; MSC 39046 .

Description

Sagittae primarily of ovate shape; height/length ratio around 70%. Smooth margins. Anterior margin broadly rounded. Anterodorsal slope shorter and noticeably steeper than posterodorsal slope. Dorsal margin quite short, almost straight. Posterodorsal slope incurved, longer than anterodorsal slope.Posterior sharply rounded. Ventral margin broadly rounded, but posteroventral slope is slightly steeper. Smooth inner face moderately convex or inflated, slopes toward the margins. Extremely wide, undivided, long (approximately 98% of the otolith length) sulcus. Very fine incised line marks sulcus. Sulcus extending essentially from anterior margin to very near posterior margin. Very small ostial channel opens on anterior margin (visible on well-preserved specimens). Dorsal margin of sulcus closer to dorsal margin than ventral margin of sulcus is to ventral margin. Dorsal margin of sulcus noticeably flexed upward anterior to the vertical midline of the otolith. Ventral margin of sulcus slightly curved or sinuous. Cristae not developed; no depressed area observed. Ventral furrow absent. Outer face slightly and irregularly concave, commonly sculptured with smooth bosses and rugosities, especially in dorsal area.

Remarks

The sagitta of Signata nicoli is very similar to S. stenzeli , but there are some distinct differences. The flexure on the dorsal margin of the sulcus of S. nicoli is not nearly as pronounced as on S. stenzeli , and the ventral margin of S. nicoli has little or no flexure upward. Additionally, the posterodorsal slope on S. nicoli is incurved rather than outcurved as on S. stenzeli .

Stratigraphic and geographic range in Alabama

The singular specimen was recovered from the “upper” Lisbon Formation at site ACh-8. Bartonian, zones NP16 and NP17.

Figures

Fig. 70. Claiborne Group, “upper” Lisbon Formation, otoliths. A–B. Diretmus? cf. D. serratus (Müller, 1999), MSC 42212. A. Inner face (left sagitta). B. Anterior view. — C–D. Preophidion meyeri (Koken, 1888), MSC 39055. C. Inner face (right sagitta). D. Dorsal view. — E–F. Preophidion cf. P. petropolis Frizzell & Dante, 1965, MSC 42193. E. Inner face (right sagitta). F. Dorsal view. — G–H. Signata stenzeli Frizzell & Dante, 1965, MSC 39051. G. Inner face (left sagitta). H. Dorsal view. — I–J. Signata nicoli Frizzell & Dante, 1965, MSC 39046. I. Inner face (left sagitta). J. Dorsal view. — K–L. Hoplobrotula melrosensis (Frizzell & Dante, 1965), MSC 37059.3. K. Inner face (right sagitta). L. Dorsal view. — M–N. Lepophidium? mucronata (Koken, 1888), MSC 39054. M. Inner face (left sagitta). N. Dorsal view. — O–P. Gobiidae Cuvier, 1816, indet. MSC 39045. O. Inner face (left sagitta). P. Dorsal view. — Q–R. Bothidae Smitt, 1892, indet. MSC 42235. Q. Inner face (right sagitta). R. Dorsal view. Scale bars: A–P= 2 mm; Q–R =1 mm.