Rhinobatos ” bruxelliensis ( Jaekel, 1894 ),

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: 106-108

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.3664639

persistent identifier

http://treatment.plazi.org/id/18174D41-FFEC-FFC4-FDD8-9B034E940C68

treatment provided by

Plazi

scientific name

Rhinobatos ” bruxelliensis ( Jaekel, 1894 )
status

 

Rhinobatos ” bruxelliensis ( Jaekel, 1894) 

Fig. 38View Fig

Rhinobatus bruxelliensis Jaekel, 1894: 77  , fig. 8.

Rhinobatos bruxelliensis – Cappetta 1976: 564  , pl. 4, fig. 7.

Rhinobatos sp.  – Holman & Case 1988: 328.

Rhinobatis sp.  – Feldmann & Portell 2007: 90.

Pristidae  oral teeth?” – Cappetta & Case 2016: 62, pl. 10, figs 5–8.

Material examined

UNITED STATES OF AMERICA – Alabama • 68 isolated teeth; Claiborne Group ; ALMNH PV1993.7.490 (5 specimens), MSC 35787.1View Materials 3View Materials, MSC 37315.1View Materials 2View Materials, MSC 37550.1View Materials 9View Materials, MSC 37670.1View Materials 2View Materials, MSC 37689.1View Materials 8View Materials, MSC 37902View Materials, MSC 37903.1View Materials 2View Materials, MSC 37903.2View Materials, SC 2012.47.1, SC 2012.47.2, SC 2012.47.3 (20 specimens), WSU 10View Materials, WSU CC 445View Materials, WSU CC 505View Materials (2 specimens), WSU 5049View Materials (10 specimens)  .

Description

Teeth extremely small, most not exceeding 2 mm in mesiodistal width. Crown has weakly convex, smooth labial face with broadly convex crown foot. Lingual face bearing three uvulae, separated by a transverse crest of varying lengths. Medial lingual uvula is most prominent; being narrow and elongated towards the succeeding tooth. Lateral uvulae are much shorter and divergent. Uvulae extend onto upper surface of root and have rounded extremities. Faint longitudinal ridge may be present on medial uvula. Most teeth lack cusps; some have taller, more cuspidate crown (see Fig. 38View Fig Q–T). Root positioned lingually under the crown. Root T-shaped in basal view. Lateral root extremities project below the lateral crown uvulae. Prominent nutritive groove extends labiolingually across the root base. Nutritive foramen present within nutritive groove; additional foramina often visible on lingual root face.

Remarks

The Rhinobatos  teeth in our sample are conspecific with those of Rhinobatos bruxelliensis ( Jaekel, 1894)  in that the lateral uvulae are divergent, with the medial uvula being more pronounced than the lateral ones, and the uvulae all have rounded extremities. The teeth also have a characteristic apical transverse ridge that separates the crown into labial and lingual faces. Holman & Case (1988) and Feldmann & Portell (2007) each reported specimens they assigned to Rhinobatos  sp. from the contact of the Tallahatta and Lisbon formations at site ACov-11. Although these specimens were not examined as part of this study, our sample included numerous Rhinobatos  specimens collected from the same locality, all of which fall within the morphological range of R. bruxelliensis  . This suggests the Holman & Case (1988) and Feldmann & Portell (2007) specimens also belong to this taxon.

Cappetta & Case (2016) figured four specimens (pl. 10, 5–8) from the ACov-11 locality that have the R. bruxelliensis  morphology. These authors, however, questioned the identification of the teeth as Rhinobatos  , suggesting instead they belong to a member of the Pristidae Bonaparte, 1838  . Although teeth of these two taxa are similar, Cappetta & Case (2016) appear to argue for a pristid identification simply because their sample included numerous Pristis Linck, 1790  rostral spines, but otherwise lacked Pristis  oral teeth. This interpretation seems problematic, as teeth of very similar morphology, identified as Rhinobatos  , have been reported from Cretaceous strata, a time well before the first occurrence of the Pristidae  in the Paleogene (see Cappetta 2012). Furthermore, Pristis  teeth have a very elongated medial lingual uvula but lack lateral uvulae ( Carrillo-Briceño et al. 2015, 2016), which is inconsistent with the teeth in our sample.

We do concur that the teeth of the bruxelliensis  morphology are dissimilar to those of the extant Rhinobatos  , and the tooth morphology of living and fossil rhinobatid species should be reviewed. Recent phylogenetic studies have shown Rhinobatos  to be paraphyletic (see Naylor et al. 2012; Claeson et al. 2013), calling into question the placement of fossil and living species within this genus, and casting doubt that they can all be placed into the family Rhinobatidae  . Thus, we provisionally assign the bruxelliensis  teeth in our sample to “ Rhinobatos  ” and place them tentatively within the Rhinobatidae  .

Stratigraphic and geographic range in Alabama

The specimens in our sample were collected from the lower Tallahatta Formation at site ADl-1, the basal Lisbon Formation at site ACov-11, the “upper” Lisbon Formation at site ACh-8, and the basal Gosport Sand at site ACl-4. Upper Ypresian to middle Bartonian, zones NP14 to NP17.

Family Pristidae Bonaparte, 1838 

ALMNH

Alabama Museum of Natural History

Kingdom

Animalia

Phylum

Chordata

Class

Elasmobranchii

Order

Rajiformes

Family

Rhinobatidae

Genus

Rhinobatos

Loc

Rhinobatos ” bruxelliensis ( Jaekel, 1894 )

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

Rhinobatus bruxelliensis

Jaekel O. 1894: 77
Loc

Rhinobatos bruxelliensis –

Cappetta H. 1976: 564
Loc

Rhinobatos sp.

Holman J. A. & Case G. R. 1988: 328
Loc

Rhinobatis sp.

Feldmann R. & Portell R. W. 2007: 90
Loc

Pristidae

Cappetta H. & Case G. R. 2016: 62