Vertipecten columbianum (Clark & Arnold, 1923)
CLARK, B. L. & R. ARNOLD. 1923. Fauna of the Sooke Formation, Vancouver Island. University of California Publications, Bulletin of the Department of Geological Sciences, 14 (5): 123-234, pls. 15-42. [p. 139, pl. 23, figs. 1, 2]
1923 Pecten columbianum Clark & Arnold, 1923
B. L. Clarck & R. Arnold, 1923, plate 23.
Pecten porterensis Weaver, Paratype, Univ. Calif. No. 30079; B. L. Clark & R. Arnold, 1923, Fauna of the Sooke Formation, plate 24, figure 1.
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«P. branneri Arnold and Hannibal in part, not P. branneri Arnold, Proc. Am. Phil. Soc., vol. 52, p. 576, 1913.
Type.— No. 30056, Univ. Calif. Coll. Invert. Pal.; L. S. J. U. locality N. P. 130.
Cotype. — No. 592, Calif. Acad. Sci. ColI. Invert. Pal.; Calif Acad. Sci. locality 232. Shell fairly large, height greater than length, dorsal slopes long and straight; apical angle less than 90 degrees, ears prominent, anterior ears about a third longer than posterior. Anterior right ear long and narrow, sculptured by four or five fairly healy radiating ribs with interspaces slightly less than width of ribs; byssal notch deep and broad and on its dorsal edge are a number of fairly prominent ctenidial teeth, ten of these teeth on type. Posterior ear broad; four heavy radial ribs on posterior ear of type with interspaces somewhat wider than width of ribs with a finer riblet in at least two of interspaces. Main surface of shell sculptured by about 24 bifurcated fairly heavy, round radiating ribs which are slightly less prominent near the dorsal margins and tend to pair, each pair separated by a wider interspace than that separating the individual members of pair; most of these pairs might be described as individual bifurcating ribs, the bifurcation taking place well up toward the beaks; some of the pairs, however, may be traced as distinct ribs up to the beaks. Irregularity of interspacing between pairs is noticeable and some of the individual ribs are bifurcated. Fine interrib in some interspaces. Surface of shell sculptured by fairly heavy concentric lines of growth which produce rather coarse imbrications where they cross ribs. Imbrications probably appeared as spines on uneroded specimens. Left valve unknown. Dimensions of type specimen (smaller of two specimens figured): Height 82.5 mm.; length probably about 75 mm.; length of hinge line about 47 mm. Dimensions of cotype: Height 96 mm.; length about 85 mm.
This specimen is very similar to P. porterensis Weaver [28] (see fig. 1, plate 24). As may be seen from the figures of the two species the character of the ribbing is quite different in the details of the bifurcations and spacing; on P. porterensis the ribs are finer and more numerous along the dorsal margins. The ribs on the ears of P. porterensis are finer and more numerous and the concentric lines of growth are finer, the result being a much more finely imbricated surface Occurrence.— Leland Stanford Jr. University localities N. P. 130, 131, and 134; California Academy of Sciences locality 232; Geological Survey of Canada locality 603.» [28] Weaver, C. E., Preliminary report on the Tertiary paleontology of western Washington, Wash. Geol. Surv., Bull. 15, p. 57, 1912.
BRUCE LAWRENCE CLARK & RALPH ARNOLD, 1923
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«The genus ranges from the Gulf of Alaska to Washington in the upper Eocene upper Galvinian (the old "Lincoln") Stage of Armentrout (1975). Two Alaskan species, V. popofensis and V. lachenbruchi, were described by MacNeil (1967) from the Eocene to Oligocene Acila shumardi zone of Schenck (1936). More recently refined chronozones, based on species of Acila, restrict the A. shumardi zone and its Vertipectens to the late Eocene Galvinian Stage (Addicott, 1976c). These species and V. porterensis (Weaver, 1912) from Washington and V. yneziana from California constitute the oldest known Vertipectens. They are included, with V. columbianum (Clark and Arnold, 1923) from the Sooke Formation, Vancouver Island, in figure 12 to summarize the range data currently known for Vertipecten.
SMITH, J. T. 1991. Cenozoic Giant Pectinids from California and the Tertiary Caribbean Province: Lyropecten, "Macrochlamis", Vertipecten, and Nodipecten species. United States Geological Survey Professional Paper, 1391: v + 1-155, figs. 1-18, pls. 1-38. [p. 37]
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«Comments.—The holotype is a very thick shelled right valve, lacking the anterior auricle and most of the disk. The ribs are large, subrounded, and lamellose. The preserved portions of the valve indicate it was inequilateral. The anterior auricle is missing, but 10 ctenolial teeth are preserved. The right posterior ear has 5 large riblets and 2 small ones.
Geographic range.— British Columbia; southern California. Geologic range.— Eocene to Miocene. Occurrence in California.— Eocene and Oligocene: San Emigdio (Eocene and Oligocene) and Pleito (Oligocene) Formations, undifferentiated (Hammond, 1958).» MOORE, E. J. 1984. Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae. United States Geological SurveyProfessional Paper, 1228-B: iv + B1-B112, figs. 1-2, pls. 1-42. [p. B30]
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Leochlamys? columbiana (Clark and Arnold); E. J. Moore, 1984, Tertiary Marine Pelecipods of California, plate 8, figure 3.
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«Observations. P. columbianum differs from P. porterensis, which it resembles somewhat closely in general outline and appearance, in the presence of numerous finer subsidiary radiating ribs on both the major ribs and interspaces and also in a larger number of closely spaced ribs on the ears. Fine concentric growth lines are well developed.
Holotype. (U.C. 30056.) Figured in the present report, pl. 16, fig. 1.
Cotype. (C.A.S. 592.) Figured in the present report, pl. 15, fig. 3. Geologic range. Sooke formation, upper Oligocene. Geographic distribution. Southern slope of Vancouver Island, Canada. Type locality. (S.U. N.P. 130.) In basal sandstone in sea cliffs at mouth of Fossil Creek, 2 miles west of Sherringham Point, Jordan River, Vancouver Island.» WEAVER, C. E. 1943. Paleontology of the marine Tertiary formations of Oregon and Washington. University of Washington Publications in Geology, Volume 5 [1942], (parts 1-3), p. 1-789, pls. 1-104. [p. 84]
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Pecten (Chlamys) columbianum Clark and Arnold; C. E. Weaver, 1943, Paleontology of the marine Tertiary formations of Oregon and Washington, plate 15, figure 3; plate 16, figure 1.
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