Washington State (USA) trigoniids (Bivalvia) from the conglomerate of Patterson Lake (Early Cretaceous)
Author
Halligan, William Keith
text
PaleoBios
2023
2023-07-03
40
8
1
15
http://dx.doi.org/10.5070/p940856601
journal article
10.5070/P940856601
0031-0298
13176106
0BD8017F-81E3-4C68-B8E8-052748786580
EARLPACKARDIA
COOPER, 2015
B
Diagnosis—
Small to moderately large, posteriorly produced and oblong, with prominent umbones, subparallel ventral and posterodorsal margins and broadly-rounded respiratory margin; prominent/conspicuous marginal carina/angulation persisting into middle growth; flank costae fine to coarse, wavy, subno- date, irregular anteriorly and sometimes discontinuous, becoming subcommarginal to nearly horizontal by mid-flank where they fade and are replaced by fine growth lines posteriorly. Area and escutcheon in some species may be costellate in early growth but are otherwise flat and unornamented except for fine growth lines.
Neocomian – Turonian
(Emended from
Cooper 2015b
)
Figure 10.
Earlpackardia methowensis
n. sp.
, holotype UWBM 112559 from UWBM loc. 9486.
A.
Flank view. Dotted line indicates proposed reconstruction of missing shell based on growth lines.
B.
Oblique view demonstrating the umbo, marginal carina, unornamented area, and escutcheon.
C.
Dorsal view demonstrating the pointed beak and degree of inflation.
D
. Oblique dorsal view showing the incurved umbo, unornamented area, and escutcheon. Scale bar = 1 cm.
Referred Species—
E. jacksonensis
(
Packard, 1921
)
, p. 18, Plate 4, fig. 1.
E. yeharai
(
Kobayashi, 1954
)
, p. 77;
Tashiro 1990
, p. 12, plate 1, fig. 3-6, text-fig. 7.
E. amagensis
(
Kobayashi, 1957a
)
p. 360, plate 3, fig. 2;
Hayami 1968
, p. 178, plate 21, fig. 6.
Occurrence—
Cordilleran, Oriental, and Sinian provinces (
Cooper 2015b
).