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.
Author
Cicimurri, David J.
Author
Stringer, Gary L.
text
European Journal of Taxonomy
2019
2019-12-06
585
1
274
journal article
https://doi.org/10.5852/ejt.2019.585
dca608e8-fccf-4c1c-b8df-ef0c28e1d518
3660259
181B6FBA-ED75-4BB4-84C4-FB512B794749
Gen. et sp.
indet
.
Fig. 61
I–Q
Material examined
UNITED STATES OF AMERICA
–
Alabama
• 66 isolated teeth;
Claiborne Group
;
ALMNH
PV1989.4.105.1,
ALMNH
PV
1989.4.18
(
3 specimens
),
ALMNH
PV1989.4.185.2 (
2 specimens
),
ALMNH
PV1989.4.84.2 (
5 specimens
),
ALMNH
PV1992.28.32 (
2 specimens
),
ALMNH
PV2016.4.38,
MMNS
VP-5645,
MMNS
VP-8225 (
2 specimens
),
MMNS
VP-8236,
MSC
188.117
,
MSC
188.275
,
MSC
2398
,
MSC
37111,
MSC
37122,
MSC
37269
(
5 specimens
),
MSC
37297
,
MSC
37463.1
–
5
,
MSC
38513
,
MSC
38537.1
–
9
,
MSC
38561.1
(
7 specimens
),
MSC
38786,
MSC
38792,
MSC
38793,
MSC
38838,
MSC
38867
(
6 specimens
),
NJSM
24045
,
NJSM
24326
,
WSU
44
,
WSU
CC 461
,
WSU
CC 503
.
Fig. 61.
Osteoglossidae Bonaparte, 1832
and
Ariidae Berg, 1958
, elements.
A–H
.
Osteoglossidae
.
A–B
. Tooth,
MSC
35778.1, lower Tallahatta Formation.
A
. Lingual view.
B
. Basal view.
C–D
. Tooth,
MSC
38444, Tallahatta/Lisbon formation contact zone, courtesy of James Lowery.
C
. Lateral view.
D
. Basal view.
E–F
. Tooth,
MSC
37515, basal Gosport Sand.
E
. Lingual view.
F
. Basal view.
G–H
. Tooth,
MSC
37307.1, basal Lisbon Formation.
G
. Lingual view.
H
. Basal view. —
I–Q
.
Ariidae
.
I–L
. Pectoral spine,
MSC
37122, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan.
I
. Anterior view.
J
. Posterior view.
K
. Lateral view.
L
. Transverse section.
M–O
. Pectoral spine,
MSC
2398, Gosport Sand.
M
. Anterior view.
N
. Dorsal view.
O
. Posterior view.
P–Q
. Pectoral spine,
MSC
37111, Tallahatta/Lisbon formation contact zone, courtesy of Bruce Relihan.
P
. Lateral view.
Q
. Posterior view. Scale bars: A–H=2 mm; I–Q=1 cm.
Description
Fin spines dorsoventrally or mediolaterally compressed (depending on position), tapered distally, weakly convex proximodistally. Some specimens with rounded anterior margin, posterior margin rather flat, with shallow furrow; single row of basally directed denticles emanates from furrow; denticles decrease in size distally. Other specimens with single row of denticles on anterior and posterior edges; anterior margin denticles directed towards the distal tip, those on the posterior edge basally directed. Lateral surfaces bearing numerous irregular sub-parallel to parallel ridges (separated by narrow furrows) extending length of spine.
Remarks
Numerous Paleogene species of sea catfish, particularly
Arius
, have been erected based on isolated fin spines, all of which are based on variations in spine base morphology, ornamentation, and the nature of the anterior and posterior denticulations (
Leriche 1922
;
White 1926
). It is unclear if the varied morphologies present in our sample represent the numerous species that have been described, or variation in a more limited number of species. One Gosport specimen resembles spines of
Arius heward-belli
described by
White (1926)
, but it is also similar to material identified by
Leriche (1922)
as belonging to a juvenile individual of
A. dutemplei
. Compounding this issue, denticles are known to occur on spines of other taxa of sea catfish like
Bagre
sp., and we therefore choose to limit the taxonomic identification of the Claiborne Group specimens to the familial level until more complete material is recovered.
Numerous other teleost fin spines were identified within the Claiborne sample we examined, but these differ from those of the
Ariidae
in having smooth dorsal and ventral surfaces. The posterior margin on these spines bear a deep V-shaped groove, the anterior and posterior margins lack denticles, and the spine base is yoke-shaped (indicating they are dorsal spines). These spines have been assigned by other researchers to indeterminate percomorph fish (see
Weems 1999
), but we identify them only as Teleostei.
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, the basal
Lisbon
Formation at site ACov-11, the “upper”
Lisbon
Formation at site ACh-8, the basal Gosport Sand at site ACl-4, and the Gosport Sand at site ACh-21. Lower Lutetian to middle Bartonian, zones NP14 to NP17.