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. 67
Material examined
UNITED STATES OF AMERICA
–
Alabama
• 1 isolated tooth;
Claiborne Group
;
MSC
2402
.
Description
Teeth anteroposteriorly longer than wide, laterally compressed covered with thick enameloid. Anterior half of tooth wider than posterior half, resulting in pear-shaped occlusal outline. Indistinct cusp located anteriorly, posterior margin slopes towards edge of tooth. Blunt transverse ridge extends across cusp; cusp conspicuously lighter in color than remainder of tooth. Lateral surfaces of crown convex, exhibiting fine growth lines. Basal face rounded.
Remarks
MSC
2402 (
Fig. 67
) appears to be conspecific with teeth belonging to the
Balistidae
as described by
Tyler (1980)
and
Tyler & Santini (2002)
.
Tyler & Santini (2002)
noted that isolated teeth and jaw fragments have little taxonomic value because the majority of differential characteristics among the described fossil taxa are based on complete specimens, not isolated teeth. The only reported Eocene member of the
Balistidae
,
Gornylistes prodigiosus
Bannikov & Tyler, 2008
, was described from a nearly complete specimen from the middle Eocene of the Caucasus. Although the
type
description for this specimen mentions the number of teeth in the jaws, the tooth morphologies were not described nor were they illustrated.
The teeth of
Balistidae
are superficially similar to the pharyngeal teeth of the Eocene fish
Eotrigonodon
. However, teeth of
Balistidae
teeth differ by having convex lateral edges, as opposed to being mesiodistally compressed with flat lateral edges on the teeth of
Eotrigonodon
(see
Ciobanu 2011
: figs 5–10). Furthermore, the crown of
Eotrigonodon
teeth has smooth enameloid that lacks transverse growth lines, which are visible on the teeth of
Balistidae
.
Fig. 67.
Balistidae Risso, 1810
, tooth.
A–D
.
MSC
2402, Gosport Sand.
A
. Profile view.
B
. Basal view.
C
. Oral view.
D
. Anterior view. Anterior at left in A–C. Scale bar = 5 mm.
Stratigraphic and geographic range in
Alabama
The lone specimen in our sample was collected from the Gosport Sand at site ACh-21. Middle Bartonian, Zone NP17.