Trichiurus oshosunensis White 1926
Creators: name: Ebersole, Jun A.
name: Cicimurri, David J.
name: Stringer, Gary L.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Perciformes
Trichiuridae
Trichiurus
Trichiurus oshosunensis

description: Trichiurus oshosunensis White, 1926
Fig. 63 J–R
Trichiurus oshosunensis White, 1926: 65–66, pl. 16, figs 14–20.
Sphyraena sp. – Maisch et al. 2016: 8, fig. 2, 19–22.
Trichiurides oshoshunensis – Arambourg 1952: 264, pl. 35, figs 47–52.
Trichiurides sp. – Thurmond & Jones 1981: 106, fig. 50.
Material examined
UNITED STATES OF AMERICA – Alabama • 33 isolated teeth; Claiborne Group; ALMNH PV1985.87.2, ALMNH PV1985.87.3, MSC 37146, MSC 37173.1 – 2, MSC 37308.1 – 7, MSC 37657, MSC 37666.1 – 2, MSC 38437, MSC 38438, MSC 38489.1 – 7, NJSM 24042, NJSM 24319, SC 2012.47.97, SC 2012.47.98 (5 specimens), WSU CC 548.
Description
Teeth measuring over 1.0 cm in height. In profile, basal one-third of tooth vertical, but then sharply curved posteriorly; apical portion anteriorly directed. Anterior margin formed into sharp carina, whereas posterior margin uniformly convex. Enameloid generally not preserved, but small apical posterior barb sometimes present. Tooth base with teardrop-shaped outline, shallow pulp cavity may be present.
Remarks
The teeth described above appear to be conspecific with White’s (1926) Trichiurus oshosunensis from the early-to-middle Eocene of Nigeria. Although similar to the Sphyraena laniary teeth we examined, they can be distinguished by being much more sinuous in profile. In contrast, laniary teeth of Sphyraena have an oblique, slightly sinuous anterior margin but nearly vertical posterior margin. Arambourg (1952: pl. 35, figs 43–45, 53–56) figured several teeth he assigned to T. oshosunensis that better fit our definition of Sphyraena sp. in that they have anterior and posterior carinae and are lanceolate in form. Unfortunately, White (1926) only illustrated laniary teeth, and the morphology of other T. oshosunensis teeth is uncertain. Until more complete specimens are known, we restrict the usage of T. oshosunensis to teeth that match White’s (1926) type description.
Trichiurus oshosunensis differs from Eutrichiurides plicidens comb. nov. in having a single anterior carina and by lacking posterior crown ornament. It differs from Trichiurides sagittidens in being laterally compressed along the entire crown height (not just apically), by having a smaller posterior barb (if present), and by having a teardrop-shaped basal outline (not circular). A laniary tooth identified as Sphyraena sp. by Maisch et al. (2016) is herein considered to be T. oshosunensis. Also, our examination of a specimen that Thurmond & Jones (1981: fig. 50) referred to Trichiurides sp. (specimen ALMNH PV2005.6.432) is also referred to T. oshosunensis.
Several of the teeth in our sample lack a posterior barb, a feature that Gago (1997) noted as being absent on juveniles of extant Trichiurus and could reflect ontogeny as opposed to jaw heterodonty.
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, and the basal Lisbon Formation at site ACov-11. Lower Lutetian, zones NP14 and NP15.
description: Published as part of 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, pp. 1-274 in European Journal of Taxonomy 585 on pages 172-173, DOI: 10.5852/ejt.2019.585, http://zenodo.org/record/3660259