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
Sciaena intermedius
(
Koken, 1888
)
Fig. 71
O–P
Otolithus
(
Sciaenidarum
)
intermedius
Koken, 1888: 283
, pl. 19, figs 2–3.
Otolithus
(
Sciaenidarum
)
intermedius
–
Campbell 1929a: 265
, pl. 30, figs 2–3.
Corvina intermedia
–
Frizzell & Dante 1965: 694
, pl. 88, figs 9–10, 27, 29–30.
“genus
Sciaenidarum
”
intermedia
–
Breard & Stringer 1999: 135
.
?“genus aff.
Umbrina
”
livesayi
–
Müller 1999: 163
, pl. 33, figs 23–30, pl. 34, figs 1–2.
“genus
Sciaenidarum
”
intermedius
– Nolf 2003: 17
, pl. 2, figs 12–14.
“
Sciaenida
”
intermedia
–
Nolf 2013: 107
, pl. 282.
Material examined
UNITED STATES OF AMERICA
–
Alabama
• 76 otoliths; GLS otolith comparative collection (
65 specimens
),
MSC
39042.1
,
MSC
39042.2
,
MSC
39042.4
,
MSC
39042.5
,
MSC
39042.6
,
MSC
39042.8
,
MSC
39042.14
,
MSC
39050,
MSC
189
,
MSC
7302
,
WSU
CC 473.1
.
Description
Sagittae with approximately oval to subrectangular outline. Height/length ratios ranging from around 75–90%, typically around 80%. Inner face convex, smooth. Margins smooth except for juveniles, which may be finely sinuate. Dorsal margin slopes gently downward anteriorly and posteriorly from an obtuse central angle. Conspicuous posterodorsal angle. Posterior margin arches inward slightly; ventral margin broadly rounded. Anterior margin very broadly, evenly rounded. Very prominent heterosulcoid-type sulcus. Ostium filled with colliculum, covers about 35% of length of inner face. Anterior of ostium even with anterior margin of sagitta. Dorsal and ventral margins of ostium tend to constrict anteriorly; constriction often more pronounced on smaller (juvenile) specimens. Cauda long and narrow (less than 50% of width of ostium), has horizontal portion and sharply downturned portion. Horizontal portion of cauda about the same length as downturned portion, less excavated (but a variable feature). Downturned portion of cauda more excavated, about same width as horizontal portion. Angle of horizontal and downturned portions approximately 90-degrees. Downturned portion nearly reaches posteroventral margin. End of cauda tapered, still somewhat rounded. Outer face usually slightly concave, sculptured.
Remarks
There has been much debate about the taxonomic position of this species, and our decision to refer to it as
Sciaena intermedius
is defended in the ensuing discussion. The sagittae of
S. intermedius
are similar to those of
Jefitchia copelandi
and
J. claybornensis
(see below), and in fact
S. intermedius
is believed to be closely related to the two
Jefitchia
species.
Frizzell & Dante (1965)
proposed the fossil genus
Jefitchia
, and John Fitch, then Research Director of the
California State
Fisheries Laboratory, considered one of the most knowledgeable experts on sciaenid otoliths, confirmed that the genus was distinct from all known Recent sciaenids. In his treatise on modern and fossil
Sciaenidae
otoliths,
Schwarzhans (1993)
also considered
Jefitchia
as a valid fossil-based genus, and he accepted the two species proposed by
Frizzell & Dante (1965)
.
Sciaena intermedius
could be considered as a possible species of
Jefitchia
, but it differs significantly from the original description of
Frizzell & Dante (1965)
and the subsequent description of
Schwarzhans (1993)
to be placed in this genus. One of the primary differences between the two is in the inflated ostium on
S. intermedius
.
Frizzell & Dante (1965)
noted the similarity of
S. intermedius
to
J. copelandi
, but they chose to assign the form to
Corvina intermedia
.
Schwarzhans (1993)
placed
Sciaena intermedius
into synonymy with the fossil-based
Frizzellithus gemma
, but Nolf rejected the fossil-based genus and insisted that
F. gemma
was actually
Aplodinotus gemma
(Nolf 2003, 2013). Furthermore, Nolf did not believe that
S. intermedius
belonged with
Aplodinotus gemma
and that it represented a separate species (Nolf 2003).
Sciaena intermedius
bears a striking similarity to the late Eocene-Oligocene sciaenid
Sciaena pseudoradians
.
Sciaena pseudoradians
was originally described as
Corvina pseudoradians
by
Frizzell & Dante (1965)
. Unfortunately, the
holotype
was not figured, and the figured
paratypes
were juvenile otoliths, which were not diagnostic. Nolf (2003) figured a growth series of the taxon and thought that the otoliths of this species seemed to be most closely related to those of
Sciaena
. Thus, the species
S. pseudoradians
was proposed.
Sciaena intermedius
has several major morphological features in common with
S. pseudoradians
, which can be clearly seen in figures 3–6 and
12–14 in
plate 2 of
Nolf (2013)
. The outline of the sagittae of the two species, the shape of the ostium, the angle of the downturned portion of the cauda, and the proportion of the horizontal and downturned portions of the cauda appear to indicate a close relationship. The width of the ostium of
S. intermedius
is variable, but it does not reach nearly the width of the ostium in
S. pseudoradians
. However, the width of the ostium of
S. intermedius
is much greater than
Jefitchia copelandi
or
J. claybornensis
.
The relationship of
S. intermedius
to
S. pseudoradians
seems to be supported by geometric morphometric analyses reported by
Lin (2018
: fig. 5). According to his study,
S. intermedius
(reported as “
Sciaenda
”
intermedia
) may be closely related to
S. pseudoradians
.
If
S. intermedius
is a transitional form to
S. pseudoradians
, this could explain the difficulty in determining its taxonomic position. It should also be noted that
S. pseudoradians
is primarily an Oligocene taxon, and that
Nolf & Stringer (2003)
identified the late Eocene form from the Yazoo Clay as
Sciaena
aff.
pseudoradians
.
No specimens of
Sciaena pseudoradians
are known from the Claiborne Group.
The sagittae of
Sciaena intermedius
are somewhat similar to
Jefitchia copelandi
, which are also found in the Claiborne Group of
Alabama
. However,
S. intermedius
is distinguished by its appreciably wider ostium. The downturned portion of the cauda of
J. copelandi
also tends to be 90-degrees or greater measured from horizontal (
Nolf 2013
: pl. 281), whereas
S. intermedius
is typically less than 90-degrees from horizontal, which is shown well in the three specimens illustrated by
Nolf (2013
: pl. 282). The
type
locality for
S. intermedius
(as
Corvina intermedia
) was given as the
Lisbon
Formation at site AMo-
4 in
Monroe County,
Alabama
(
Frizzell & Dante 1965
), and the species is also known from
Louisiana
,
Mississippi
, and
Texas
.
In his description of Eocene fishes of Alabama,
White (1956)
discussed a small collection of remains collected by G.F. Harris from the Gosport Sand of Claiborne, Monroe County, Alabama. Harris donated the material, which was composed primarily of shark teeth, to the British Museum in 1892, and a single otolith (P.6827) was included in the remains.
White (1956)
noted that the otolith belonged to Koken’s species
Otolithus
(
Sciaenidarum
)
intermedius
(
Koken 1888
: table 19, figs 2–3), which is the same as
Corvina intermedia
(Koken)
of
Frizzell & Dante (1965)
. However,
White (1956)
then stated that “Mr. Stinton” informed him that the specimen belonged to
Lutianus
.
It is presumed that the “Mr. Stinton” refers to F.C. Stinton, a renowned expert on fossil otoliths, who published extensively on the Eocene otoliths of
England
. Although the otolith specimen was not examined as part of the present study, the background information provided by
White (1956)
is nevertheless problematic. If the otolith was correctly identified as
Otolithus
(
Sciaenidarum
)
intermedius
, then it is highly unlikely that Stinton would identify it as
Lutianus
(it should be noted that
Lutianus
is a rejected spelling for
Lutjanus
Bloch, 1790
).
Lutjanus
is in
Lutjanidae
(the snappers), and lutjanid otoliths have little resemblance to
Koken’s (1888)
Otolithus
(
Sciaenidarum
)
intermedius
. The sciaenid described by Koken has an inflated ostium and a narrow cauda that is downturned at almost 90-degrees, but
Lutjanus
displays none of these characteristics. Therefore, the identification of the Gosport Sand otolith recovered by Harris is unclear based on
White’s (1956)
discussion.
Stratigraphic and geographic range in
Alabama
Sciaena intermedius
is one of the most abundant taxa in the Claiborne Group of
Alabama
. It is common in the “upper”
Lisbon
Formation at site ACh-8 and six specimens were recovered from the Gosport Sand at sites ACl-4 and AMo-4. Bartonian, zones NP16 and NP17.