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
Hypolophodon
s
ylvestris
(
White, 1931
)
Fig. 42
M–X
Hypolophus sylvestris
White, 1931: 30
, pl. 7, figs 22–23.
Fig. 42.
Coupatezia
sp. and
Hypolophodon
s
ylvestris
(
White, 1931
), teeth. —
A–L
.
Coupatezia
sp.
A–D
.
MSC
37339, basal Lisbon Formation.
A
. Basal view.
B
. Basiolabial view.
C
. Oral view.
D
. Profile view.
E–H
.
MSC
35786.1, lower Tallahatta Formation.
E
. Basal view.
F
. Basiolabial view.
G
. Oral view.
H
. Profile view.
I–L
.
MSC
38480.2, basal Lisbon Formation.
I
. Basal view.
J
. Basiolabial view.
K
. Oral view.
L
. Profile view. —
M–X
.
Hypolophodon
s
ylvestris
.
M–O
.
MSC
35788.1, lower Tallahatta Formation.
M
. Oral view.
N
. Basal view.
O
. Lingual view.
P–R
.
MSC
35788.2, lower Tallahatta Formation.
P
. Oral view.
Q
. Basal view.
R
. Lingual view.
S–U
.
MSC
35788.3, lower Tallahatta Formation.
S
. Oral view.
T
. Basal view.
U
. Profile view.
V–X
.
MSC
35788.4, lower Tallahatta Formation.
V
. Oral view.
W
. Basal view.
X
. Lingual view. Scale bars: A–L= 1 mm; M–X= 2 mm.
Hypolophodon sylvestris
–
Cappetta 1980a
: pl. 39, fig. 6.
Dasyatis sylvestris
–
Sahni & Mehrotra 1981: 101
, pl. 3, figs 5–7. —
Sharma & Patnaik 2013: 175
, pl. 6a.
Material examined
UNITED STATES OF AMERICA
–
Alabama
• 7 isolated teeth;
Claiborne Group
;
MSC
35788.1
–
7
.
Description
Teeth small, measure up to 5.0 mm in greatest width. Crown may have rounded six-sided outline in occlusal view; more often ovate. Crown of unworn teeth covered with smooth enameloid. Occlusal, labial, and lingual surfaces convex and smooth. Lingual crown face has a small uvula and faint enameloid wrinkling at basal margin. Root low, generally divided by single nutritive groove into two triangular lobes. Root lobes may be equidimensional or of differing size, depending on location of the nutritive groove. Two or more nutritive grooves occasionally observed.
Remarks
Based on morphological and histological criteria,
Cappetta (1980b)
synonymized some species that had been placed within
Hypolophus
and
Platyrhina
with his newly created genus,
Hypolophodon
. Junior synonyms included the
type
species,
H. sylvestris
(
White, 1931
)
, and
Casier’s (1946)
P. ypresiensis
. The teeth in our sample appear to be conspecific with those of
H. sylvestris
as described and figured by
Cappetta (1980a
: pl. 39, fig. 6) in that they have enameloid wrinkling and a small uvula on their lingual crown face. The presence of lingual crown wrinkling separates the teeth in our sample from those of
H. dockeryi
Case, 1994
, which apparently lacks this characteristic (
Case 1994a
; also
Case
et al.
2015: 1132
, fig. 7.3). The teeth of
H. malembeensis
Murray
et al.
, 2010
can be separated from those in our sample by having numerous labial foramina on their root, sharper crown edges, and a distinct lingual concavity in profile view (see
Murray
et al.
2010
: figs 2c–d). Teeth of
H. farreri
Gurr, 1962
can have a similarly angular six-sided outline, but their crown faces are vertical and flat, and they lack a lingual basal protuberance. It remains to be shown if
H. farreri
is valid, as abraded specimens in our sample lack enameloid on the underside of the crown, as well as a lingual protuberance, and this latter characteristic is also absent from larger adult teeth we examined.
Casier (1967)
tentatively referred a tooth to
H. farreri
, and to our knowledge this is the only other mention of the species. However, the specimen he illustrated (
Casier 1967
: pl. VII, fig. 24) is abraded and in our opinion compares more favorably to
H. sylvestris
.
Stratigraphic and geographic range in
Alabama
The specimens in our sample were collected from the lower Tallahatta Formation at site ADl-1. Upper Ypresian to lower Lutetian, Zone NP14.
Family
Gymnuridae Jordan, 1888