Gen. et sp. indet, Berg, 1958

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 : 164-166

Gen. et sp. indet .

Fig. 61 I–Q

Material examined

UNITED STATES OF AMERICA – Alabama • 66 isolated teeth; Claiborne Group ; ALMNH PV1989.4.105.1, ALMNH PV 1989.4.18 (3 specimens), ALMNH PV1989.4.185.2 (2 specimens), ALMNH PV1989.4.84.2 (5 specimens), ALMNH PV1992.28.32 (2 specimens), ALMNH PV2016.4.38, MMNS VP-5645, MMNS VP-8225 (2 specimens), MMNS VP-8236, MSC 188.117 , MSC 188.275 , MSC 2398 , MSC 37111, MSC 37122, MSC 37269 (5 specimens), MSC 37297, MSC 37463.1 – 5 , MSC 38513, MSC 38537.1 – 9 , MSC 38561.1 (7 specimens), MSC 38786, MSC 38792, MSC 38793, MSC 38838, MSC 38867 (6 specimens), NJSM 24045 , NJSM 24326 , WSU 44 , WSU CC 461 , WSU CC 503 .

Description

Fin spines dorsoventrally or mediolaterally compressed (depending on position), tapered distally, weakly convex proximodistally. Some specimens with rounded anterior margin, posterior margin rather flat, with shallow furrow; single row of basally directed denticles emanates from furrow; denticles decrease in size distally. Other specimens with single row of denticles on anterior and posterior edges; anterior margin denticles directed towards the distal tip, those on the posterior edge basally directed. Lateral surfaces bearing numerous irregular sub-parallel to parallel ridges (separated by narrow furrows) extending length of spine.

Remarks

Numerous Paleogene species of sea catfish, particularly Arius , have been erected based on isolated fin spines, all of which are based on variations in spine base morphology, ornamentation, and the nature of the anterior and posterior denticulations ( Leriche 1922; White 1926). It is unclear if the varied morphologies present in our sample represent the numerous species that have been described, or variation in a more limited number of species. One Gosport specimen resembles spines of Arius heward-belli described by White (1926), but it is also similar to material identified by Leriche (1922) as belonging to a juvenile individual of A. dutemplei . Compounding this issue, denticles are known to occur on spines of other taxa of sea catfish like Bagre sp., and we therefore choose to limit the taxonomic identification of the Claiborne Group specimens to the familial level until more complete material is recovered.

Numerous other teleost fin spines were identified within the Claiborne sample we examined, but these differ from those of the Ariidae in having smooth dorsal and ventral surfaces. The posterior margin on these spines bear a deep V-shaped groove, the anterior and posterior margins lack denticles, and the spine base is yoke-shaped (indicating they are dorsal spines). These spines have been assigned by other researchers to indeterminate percomorph fish (see Weems 1999), but we identify them only as Teleostei.

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the contact of the Tallahatta and Lisbon formations at sites ACh-14 and ACov-11, the basal Lisbon Formation at site ACov-11, the “upper” Lisbon Formation at site ACh-8, the basal Gosport Sand at site ACl-4, and the Gosport Sand at site ACh-21. Lower Lutetian to middle Bartonian, zones NP14 to NP17.

Figures

Fig. 61. Osteoglossidae Bonaparte, 1832 and Ariidae Berg, 1958, elements. A–H. Osteoglossidae. A–B. Tooth, MSC 35778.1, lower Tallahatta Formation. A. Lingual view. B. Basal view. C–D. Tooth, MSC 38444, Tallahatta/Lisbon formation contact zone, courtesy of James Lowery. C. Lateral view. D. Basal view. E–F. Tooth, MSC 37515, basal Gosport Sand. E. Lingual view. F. Basal view. G–H. Tooth, MSC 37307.1, basal Lisbon Formation. G. Lingual view. H. Basal view. — I–Q. Ariidae. I–L. Pectoral spine, MSC 37122, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan. I. Anterior view. J. Posterior view. K. Lateral view. L. Transverse section. M–O. Pectoral spine, MSC 2398, Gosport Sand. M. Anterior view. N. Dorsal view. O. Posterior view. P–Q. Pectoral spine, MSC 37111, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan. P. Lateral view. Q. Posterior view. Scale bars: A–H=2 mm; I–Q=1 cm.