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
Author
Ebersole, Jun A.
D48E2A2F-EC92-4C32-9F2A-2D39716C459E
McWane Science Center, 200, 19 Street North, Birmingham, Alabama 35203, USA.
jebersole@mcwane.org
Author
Cicimurri, David J.
F0155EA1-F5D6-49E4-B578-7A14DBB7B902
South Carolina State Museum, 301 Gervais Street, Columbia, South Carolina 29201, USA.
dave.cicimurri@scmuseum.org
Author
Stringer, Gary L.
4E93392A-5916-44C6-B55A-9053A4F44C76
University of Louisiana at Monroe, Monroe, Louisiana 71209, USA.
stringer@ulm.edu
text
European Journal of Taxonomy
2019
2019-12-06
585
1
274
journal article
10.5852/ejt.2019.585
dca608e8-fccf-4c1c-b8df-ef0c28e1d518
2118-9773
3660259
181B6FBA-ED75-4BB4-84C4-FB512B794749
“
Rhinobatos
”
bruxelliensis
(
Jaekel, 1894
)
Fig. 38
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
35787.1
–
3
,
MSC
37315.1
–
2
,
MSC
37550.1
–
9
,
MSC
37670.1
–
2
,
MSC
37689.1
–
8
,
MSC
37902,
MSC
37903.1
–
2
,
MSC
37903.2
,
SC
2012.47.1,
SC
2012.47.2,
SC
2012.47.3 (
20 specimens
),
WSU
10
,
WSU
CC 445
,
WSU
CC 505
(
2 specimens
),
WSU
5049
(
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. 38
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.
Fig. 38.
“
Rhinobatos
”
bruxelliensis
(
Jaekel, 1894
)
, teeth.
A–D
.
MSC
35787.1, lower Tallahatta Formation.
A
. Orolingual view.
B
. Profile view.
C
. Basal view.
D
. Labial view.
E–H
.
MSC
35787.2, lower Tallahatta Formation.
E
. Orolingual view.
F
. Profile view.
G
. Basal view.
H
. Labial view.
I–L
.
MSC
37315.1, basal Lisbon Formation.
I
. Orolingual view.
J
. Profile view.
K
. Basal view.
L
. Labial view.
M–P
.
MSC
37315.2, basal Lisbon Formation.
M
. Orolingual view.
N
. Profile view.
O
. Basal view.
P
. Labial view.
Q–T
.
MSC
37550.1, male tooth, basal Gosport Sand.
Q
. Orolingual view.
R
. Profile view.
S
. Basal view.
T
. Labial view.
U–X
.
MSC
37550.2, basal Gosport Sand.
U
. Orolingual view.
V
. Profile view.
W
. Basal view.
X
. Labial view. Labial at top in basal views. Scale bars = 1 mm.
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