Abdounia minutissima (Winkler, 1874),

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, inclu, European Journal of Taxonomy 585, pp. 1-274: 86-87

publication ID

https://doi.org/10.5852/ejt.2019.585

publication LSID

lsid:zoobank.org:pub:181B6FBA-ED75-4BB4-84C4-FB512B794749

DOI

http://doi.org/10.5281/zenodo.3664599

persistent identifier

http://treatment.plazi.org/id/18174D41-FFD0-FFF9-FDE9-99444F7708DC

treatment provided by

Plazi

scientific name

Abdounia minutissima (Winkler, 1874)
status

 

Abdounia minutissima (Winkler, 1874) 

Fig. 31View Fig P–GG

Otodus minutissimus Winkler, 1874a: 23  .

Scyllium minutissimus – Daimeries 1891: 73  .

Scyllium minutissimum – Leriche 1905: 186  , pl. 5, fig. 15.

Scyliorhinus minutissumus – White 1931: 65  , fig. 80.

Abdounia minutissima – Cappetta 1980a: 37  .

Abdounia minutissimus – Baut & Genault 1995: 226  .

Scyliorhinus  sp. – Maisch et al. 2014: 192, fig. 3, 17–19.

Material examined

UNITED STATES OF AMERICA – Alabama • 71 isolated teeth; Claiborne Group ; GSA-V706, MMNS VP-8192 (3 specimens), MSC 35757.1 2, MSC 35768.1 5, MSC 37573View Materials, MSC 37574.1 2, MSC 37575.1 16, MSC 37576.1 3, MSC 37577.1 12, MSC 37694, MSC 37707, MSC 37900.1 5, SC 2012.47.49, SC 2012.47.50 (9 specimens), SC 2012.47.158, WSU 5014View Materials, WSU 5015View Materials, WSU 5032View Materials (6 specimens)  .

Description

Teeth small, most not exceeding 4.0 mm high. Main cusp of anterior teeth tall and triangular; cusp wider, lower, distally inclined on lateral teeth. Cusp flanked by single pair of tall triangular lateral cusplets in all tooth positions. Base of lateral cusplets separated from main cusp; cusplets slender, tall, erect. Cutting edges of main cusp and cusplets smooth, continuous. Lingual crown face convex, less so on lateral teeth; labial crown face flat; enameloid smooth. Root bilobate with short, diverging lobes. Lingual attachment surface flat, bisected by deep nutritive groove.

Remarks

The A. minutissima  anterior teeth in our sample have a single pair of lateral cusplets in all tooth positions, whereas two species formerly placed within Abdounia  (see below), A. claibornensis  and A. recticona  , have three-to-eight pairs. The anterior teeth of A. minutissima  were distinguished from those of A. beaugei  by having lateral cusplets that are taller, more slender, and more conspicuously differentiated from the main cusp. The teeth of A. minutissima  differ from those of A. enniskilleni  by their smaller size and more gracile appearance, by having a smooth lingual crown face, and by having narrower lateral cusplets.

Cappetta & Case (2016) referred 120 teeth from the contact of the Tallahatta and Lisbon Formation at site ACov-11 to Abdounia  sp. and questioned the assignment of teeth to A. minutissima  by Clayton et al. (2013). Cappetta & Case (2016) stated that the 120 teeth were similar to those of A. minutissima  , but noted that they lack short folds at the base of the labial crown face and have a thicker root. However, the type specimens of A. minutissima  originally illustrated by Winkler (1874a) lack any labial folds, and the presence of such ornamentation was not mentioned by either Winkler (1874a) or later by Daimeries (1891). The presence of faint labial ornamentation on the teeth of A. minutissima  was first reported by Leriche (1905), but he noted that these vertical striations are extremely faint, almost invisible to the naked eye, and were extremely susceptible to abrasion. This lack of ornamentation on certain teeth is substantiated by its absence on several figured A. minutissima  specimens by other authors, at least one of which was derived from the type locality in Belgium (see Van den Eeckhaut & De Schutter 2009: pl. 20, fig. 6). Furthermore, an examination of the A. minutissima  teeth in our sample suggests that the thickness of the root is variable and can be attributed to heterodonty. Additionally, the presence or absence of labial ornamentation, as well as root thickness and cusplet morphology, is variable in large samples of A. enniskilleni  teeth from both Alabama and South Carolina that we examined. The taxonomic utility of crown ornamentation may not be significant ( Purdy et al. 2001), as it is also variable within the various species of Premontreia  that have been identified ( Cappetta 1992; Noubhani & Cappetta 1997).

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 AMo-8, the contact of the Tallahatta and Lisbon formations and the basal Lisbon Formation at site ACov-11, the contact of the Lisbon Formation and Gosport Sand at site AMo- 4, the basal Gosport Sand at site ACl-4, and the Gosport Sand at site ACl-15. Upper Ypresian to middle Bartonian, zones NP14 to NP17.

Kingdom

Animalia

Phylum

Chordata

Class

Elasmobranchii

Order

Carcharhiniformes

Family

Carcharhinidae

Genus

Abdounia

Loc

Abdounia minutissima (Winkler, 1874)

Ebersole, Jun A., Cicimurri, David J. & Stringer, Gary L. 2019
2019
Loc

Otodus minutissimus

Winkler T. C. 1874: 23
Loc

Scyllium minutissimus –

Daimeries A. 1891: 73
Loc

Scyllium minutissimum –

Leriche M. 1905: 186
Loc

Scyliorhinus minutissumus –

White E. I. 1931: 65
Loc

Abdounia minutissima – Cappetta 1980a: 37

Cappetta H. 1980: 37
Loc

Abdounia minutissimus – Baut & Genault 1995: 226

Baut J. - P. & Genault B. 1995: 226
Loc

Scyliorhinus

Maisch H. M. & Becker M. A. & Raines B. W. & Chamberlain J. A. 2014: 192