Sphyraena, Walbaum, 1792

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 : 167-169

Sphyraena sp.

Fig. 62 A–L

Trichiurides oshoshunensis – Arambourg 1952 : pl. 35, figs 43–45, 53–56.

Trichiurides sp. – Thurmond & Jones 1981: 106, fig. 50.

Material examined

UNITED STATES OF AMERICA – Alabama • 71 isolated teeth; Claiborne Group ; ALMNH PV1993.2.496a, ALMNH PVPV 2005.6 .436.1, MSC 188.145 , MSC 188.60 , MSC 2150.1 , MSC 2150.3 , MSC 2393 , MSC 2397 , MSC 35779, MSC 37141, MSC 37142, MSC 37162, MSC 37163, MSC 37238, MSC 37286, MSC 37352.1 – 5 , MSC 37434.1 – 27 , MSC 37547, MSC 37590, MSC 38432, MSC 38436.1 – 2 , MSC 38440, MSC 38441, MSC 38505.1 – 4 , MSC 38539.1 – 3 , MSC 38973, MSC 38975, MSC 38978.1 – 2 , MSC 39877, NJSM 24320 , NJSM 24321 , SC 2012.47.99 (2 specimens), WSU CC 550 .

Description

Laniary teeth erect, with convex, straight to slightly sinuous posterior; inconspicuous posterior apical barb may be present. Anterior margin sharply carinate, sinuous, smooth. Vertical striations may occur at posterior tooth base. Tooth with teardrop-shaped basal outline; pulp cavity shallow. Dentary teeth lanceolate, very thin labiolingually; sharp, convex, smooth anterior and posterior carinae form sharply pointed apex. Labial and lingual crown faces weakly convex, smooth; crown generally erect but may curve slightly medially. Basal surface may bear shallow pulp cavity.

Remarks

Sphyraena laniary teeth could be confused with the teeth of some trichiurids, particularly Trichiurus oshosunensis . However, Sphyraena laniary teeth can be differentiated by their nearly straight posterior margin and sinuous anterior margin (as opposed to both margins being sinuous), having a teardropshaped basal outline (as opposed to circular), and by their weak to absent posterior barb. Non-laniary Sphyraena teeth are similar to Scomberomorus and Palaeocybium , but they can be separated from the former by their much narrower crown with equally convex labial and lingual faces, and carinae that reach the tooth base. Teeth of Palaeocybium can be thicker than those of Sphyraena , and the basal pulp cavity is large and deep.

The dentitions of extant Sphyraena species exhibit a range of heterodonty (see Berkovitz & Shellis 2016: fig. 4.72), making speciation of isolated fossil teeth difficult. In extant species, large, triangular laniary teeth are located at the anterior margins of the premaxilla and dentary, with those in the upper jaw being somewhat larger than those on the dentary (SC 2018.3.1). Lanceolate dentary teeth are comparable in size to those on the palatine, which fit into depressions on the dentary, and the teeth from these jaw elements are much larger than those on the premaxilla. A poorly developed posterior barb has occasionally been observed on premaxillary laniary teeth of extant and Miocene Sphyraena specimens (see Nishimoto & Ohe 1982: fig. 4k; Kriwet 2003), and this characteristic was observed on some laniary teeth in our Claiborne sample. The various fossil species have been differentiated based on size and shape of the teeth, and occasionally ornamentation (see Leidy 1877; Casier 1946, 1966; Weems 1999). Several specimens in our sample are approximately the same size as the teeth of Sphyraena striata Casier, 1946 and Sphyraena lugardi White, 1926 reported elsewhere, but unfortunately enameloid is not preserved on our specimens so they could not be adequately compared to those species. Furthermore, the differential dental characteristics attributed to the various species appears variable but temporally consistent, making specific identifications difficult. Within the Claiborne sample, teeth from the Tallahatta Formation are not morphologically dissimilar to those occurring within the Gosport Sand. As a result, we believe only a single, undetermined species is present within our sample.

Thurmond & Jones (1981: 106, fig. 50) described and figured a tooth from the Tallahatta Formation in Monroe County, AL that they assigned to Trichiurides sp. This specimen instead represents a laniary tooth of Sphyraena sp.

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the lower Tallahatta Formation at site ADl-1, the Tallahatta Formation at site AMo-8, the contact of the Tallahatta and Lisbon Formations at sites ACh-14 and ACov-11, the basal Lisbon Formation at site ACov-11, the basal Gosport Sand at site ACl-4, and the Gosport Sand at sites ACh-21 and ACl-15. Upper Ypresian to middle Bartonian, zones NP14 to NP17.

Figures

Fig. 62. Sphyraena sp. and Eutrichiurides plicidens (Arambourg, 1952) comb. nov., teeth. A–L. Sphyraena sp. A–C. MSC 37142, laniary tooth, Tallahatta/Lisbon formation contact zone, courtesy of James Lowery. A. Lingual view. B. Anterior view. C. Basal view. D–F. MSC 35779, lower Tallahatta Formation. D. Lingual view. E. Carinal view. F. Basal view. G–H. MSC 37434.1, Gosport Sand. G. Lingual view. H. Carinal view. I. Basal view. J–L. MSC 37434.2, laniary tooth, basal Gosport Sand. J. Lingual view. K. Anterior view. L. Basal view. — M–X. Eutrichiurides plicidens comb. nov. M–O. MSC 188.2, Gosport Sand. M. Lingual view. N. Mesial view. O. Basal view. P–R. MSC 37908, basal Lisbon Formation. P. Lingual view. Q. Mesial view. R. Basal view. S–U. MSC 38482, basal Lisbon Formation. S. Lingual view. T. Mesial view. U. Basal view. V–X. MSC 37460, basal Gosport Sand. V. Lingual view. W. Mesial view. X. Basal view. Scale bars: A–C, G–X =5 mm; D–F =2 mm.