Mollusks from late Mesozoic seep deposits, chiefly in California
Author
Kaim, Andrzej
Author
Jenkins, Robert G.
Author
Tanabe, Kazushige
Author
Kiel, Steffen
text
Zootaxa
2014
3861
5
401
440
journal article
42509
10.11646/zootaxa.3861.5.1
0b368704-d9cc-4a82-8248-bc4c06dcf781
1175-5326
252462
E62DB6C3-0C5F-4898-99C4-1BEC70DD1734
Oxyeurax
trapezoidalis
(
Stanton, 1895
)
(
Fig. 16
)
Astarte trapezoidalis
Stanton 1895
, p. 57–58, pl. 6, figs. 17–18.
FIGURE 16.
Oxyeurax
trapezoidalis
(Stanton, 1895)
from Cretaceous seep carbonates in California.
A.
Left valve showing the anterior adductor muscle scar, from Bear Creek (GZG.INV.85007).
B.
Dorsal view on a specimen from the Valanginian of Bear Creek showing pedal retractor scars and the sharply delineated escutcheon (GZG.INV.85008).
C.
Juvenile specimen with more oval shell shape and regular ornament, from Bear Creek (GZG.INV.85009).
D.
Dorsal view on specimen from Stanton’s type series (USNM 23104) showing the outline of the hinge dentition, from the ‘Reiff’ locality.
E-G.
Holotype (USNM 23104), from Knoxville.
Supplementary description.
Anterior adductor muscle scar slightly oval, pedal retractor scar small and round and separated from the adductor muscle scar. The pallial line is entire; on the interior of the anteroventral side of the shell, several radial grooves appear near the pallial line, run across it, but fade before reaching the margin. The posterior adductor muscle scar is indistinct. At the posterodorsal margin of the shell, the fine commarginal sculpture stops at the sharp crest that forms the edge of the escutcheon; the interior of the escutcheon is smooth. The ligament is short and reaches only about a third of the length of the escutcheon.
Material and occurrence.
27 specimens
from Bear Creek (Valanginian, Early Cretaceous), 58 from Rocky Creek (probably Valanginian, Early Cretaceous) and one from Eagle Creek (Late Barremian, Early Cretaceous); Stanton’s
type
material from Knoxville and Reiff, two localities in the general area of Rocky Creek, was also investigated (
USNM
23104).
Remarks.
Stanton (1895, p. 58)
noted that ‘internal casts (from another locality) show impressions of the hinge, which also seem to agree with it [its position within
Astarte
]’. The mentioned internal cast was found among Stanton’s
type
material (USNM 23104) and is from ‘Knoxville, near Reiff P.O.,
1 mile
N.W. of Palmer’s ranch, Morgan Valley’ (
Stanton 1895, p. 58
), which is to the south of the Rocky Creek site; this specimen shows two cardinal teeth in each valve and is illustrated here (
Fig. 16
D). A similarly elongate species with an anterior umbo is
Oxyloma cyphopleura
Gardner & Campbell, 2002
from the Middle Temaikan (Bajocian–Bathonian) Tucks Bay Formation in South Otago,
New Zealand
(
Gardner & Campbell 2002, p. 38, fig. 32
).