Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard
Author
Nakrem, Hans Arne
text
Zootaxa
2017
2017-10-06
4329
4
351
374
journal article
31875
10.11646/zootaxa.4329.4.3
54677545-2000-47a2-92ce-a03d614140d1
1175-5326
1003014
A0552Ffb-Fe2B-4Fad-809A-A1274Ac86Bcc
Cretadmete
sp.
(
Fig. 8A–C
)
2015
Maturifusidae
? gen. et sp. indet.;
Hryniewicz
et al.
2015a
, table 1.
Description.
Protoconch not preserved. Shell small,
4.5 mm
in height and
5.3 mm
in width, fusiform/turbiniform with two strongly convex whorls preserved. Suture moderately incised. Shell flank ornamented with numerous spiral cords arranged in two orders; each two 1
st order
cords sandwich one weaker 2nd order cord. The spiral ornament is crossed by prosocline axial ridges with no clear knobs and the intersections, which, however, might be slightly undulating in the adapical portion of flank. Transition between flank and base without angulation, but distinct due to disappearance of axial ornamentation and 2nd order spiral cords. Aperture poorly preserved with no apertural elaborations visible. Anterior part of the aperture broken off. No umbilicus.
Material and occurrence:
One specimen (PMO 224.762) from seep deposit #8, Sassenfjorden, Svalbard; Late Tithonian, Late Jurassic.
Remarks.
This juvenile shell is remarkably similar to
Cretadmete neglecta
Blagovetshenskiy & Shumilkin, 2006
, from the Upper Hauterivian (Early Cretaceous) of the
Ulyanovsk
Region in
Russia
.
Blagovetshenskiy & Shumilkin (2006)
included six species in
Cretadmete
ranging in age from the Oxfordian to the Albian. We refrain from placing our shell into any of these species due to its fragmentary preservation. A similar
type
of teleoconch, but with entirely different cancellate protoconch, has been reported by
Schröder (1995: pl. 7: 3–4)
in a juvenile shell from the Albian of
Germany
, which has been interpreted by
Bandel (1993)
as a species of
Rapana
and considered by him to be the oldest record of the tonnoideans.
Wollemann (1900
,
1907
,
1909
) reported from the same strata several species similar to
Cretadmete
(but without protoconchs); this entire group of taxa requires thorough review.