Before the freeze: otoliths from the Eocene of Seymour Island, Antarctica, reveal dominance of gadiform fishes (Teleostei)
Author
Schwarzhans, Werner
Ahrensburger Weg 103, D- 22359 Hamburg, Germany; & Natural History Museum of Denmark, Zoological Museum, Universitetsparken 15, DK- 2100 Copenhagen, Denmark;
Author
Mors, Thomas
Swedish Museum of Natural History, Department of Palaeobiology, P. O. Box 5007, SE- 10405 Stockholm, Sweden;
Author
Engelbrecht, Andrea
University of Vienna, Department of Palaeontology, Althanstrasse 14, 1090 Vienna, Austria;
Author
Reguero, Marcelo
Museo de La Plata, Division ́ Paleontolog ́ ıa de Vertebrados, Paseo del Bosque s / n, B 1900 FWA La Plata, Argentina
Author
Kriwet, Jurgen
University of Vienna, Department of Palaeontology, Althanstrasse 14, 1090 Vienna, Austria;
text
Journal of Systematic Palaeontology
2017
2016-03-16
15
2
147
170
http://dx.doi.org/10.1080/14772019.2016.1151958
journal article
10.1080/14772019.2016.1151958
1478-0941
PMC5221741
28077930
10883098
A30E5364-0003-4467-B902-43A41AD456CC
Notoberyx cionei
sp. nov.
(
Figs 5D—G
,
6O
)
Material.
Holotype
:
NRM-PZ P.15987
(
Figs 5D—F
,
6O
)
.
Paratypes
:
two specimens
, NRM-PZ P.15988— 15989 (
Fig. 5G
).
Occurrence.
Telm 5 unit; ‘
Natica
horizon’,
Cucullea
I member, La Meseta Formation, late Ypresian, early Eocene. Site IAA 2/95, Seymour Island,
Antarctica
.
Etymology.
Named in honour of Alberto Cione (La Plata,
Argentina
) for his many contributions to the knowledge of fossil fishes from South America and
Antarctica
.
Diagnosis.
OL:OH = 0.7—0.75. Dorsal rim high, broad; ventral rim deep, broad. Rostrum short, blunt, about equal length of antirostrum. CaL:OsL = 1.4—1.5. Ostium narrow, only slightly wider than cauda; cauda distinctly turned upwards.
Description.
Large, robust, high-bodied, oval otoliths up to about
6 mm
in length (
holotype
5.8 mm
long). OL:OT = 3.0. Dorsal rim high, much expanded and broad, undulating; rounded pre- and postdorsal angles close to anterior and posterior limits of dorsal rim, postdorsal angle usually somewhat pronounced. Ventral rim deep, nearly as broad and expanded as dorsal rim, but more gently curved and smooth. Anterior rim blunt, nearly vertically cut, with very short and massive rostrum not reaching beyond length of antirostrum; with broad, shallow excisura in between. Posterior rim likewise blunt and nearly vertically cut, its tip shifted dorsally above level of caudal tip.
Inner face bent along the horizontal axis, nearly straight in vertical direction. Sulcus slightly supramedian, wide, moderately deep. Ostium anteriorly opened, slightly deepened, distinctly shorter than cauda and only slightly wider. OsH:CaH = 1.15—1.3. Cauda long, bent upwards, terminating close to posterior rim of otolith, its colliculum with well-marked ventral rim. Dorsal depression wide, large, well defined towards sulcus; dorsal field with some short radial furrows near the dorsal margin. Ventral field smooth, with distinct ventral furrow very close to ventral rim of otolith. Outer face with broad central umbo.
Remarks.
These highly diagnostic otoliths differs from the only congener,
N. madseni
from the Northern Hemisphere, in being even more compressed (OL:OH = 0.7—0.75 vs. 0.8—0.85), the ostium being slightly wider than the cauda (vs. not being wider at all) and the absence of the peculiar deepening of the rear portion of the cauda as observed in
N. madseni
. The latter character could possibly support placing
N. madseni
in a genus of its own, once more species with this morphological pattern have become known to support a further taxonomic division.
The two species here attributed to
Notoberyx
show a bipolar temperate distribution with one species each in the early Eocene of
Antarctica
and
Denmark
, subject, however, to further finds of these highly diagnostic otoliths. The Danish Eocene otoliths of
N. madseni
were exclusively found in burrow concretions of stomatopods, apparently indicating that these fishes represented their preferred prey.