Mizuhopecten warreni Masuda, 1971
MASUDA, K. 1971. Patinopecten from North America. Transactions and Proceedings of the Palaeontological Society of Japan [N. S.], 83: 166-178, pls. 19-21 [p. 170, pl. 19, figs. 1-3; pl. 21. fig. 3]
1971 Mizuhopecten warreni Masuda, 1971
K. Masuda, 1971, plate 21.
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1966. Patinopecten n. sp., ADDICOTT, Jour. Paleont., Vol. 40, no. 3, p. 644, pl. 76, fig. 8.
«Holotype:—U. S. Natl. Mus., no. 646491.
Description:— Shell medium in size and thickness, smooth, compressed, orbicular in outline, equilateral except for auricles, subequivalve; valves radiately ribbed and forming an angle of about 110º at apex. Right valve with about 20 flattish, round-topped radial ribs and fine concentric incremental lines; radial ribs rather low, rounded, broader than their interspaces, rarely bifurcate towards ventral margin; auricles medium in size, subequal, anterior one with wide and shallow byssal notch, a few faint, fine radial threads and fine concentric lines; posterior one truncated behind forming an obtuse angle and with concentric lines; interior surface rather smooth but slightly folded corresponding to external sculpture. Left valve with low, rounded, fine radial ribs, fine intercalary threads, fine concentric line; and rather obscure fine network; intercalary threads usually appear at middle of shell length and tend to become somewhat distinct towards ventral margin; radial ribs much narrower than their interspaces. Hinge with simple, fine cardinal crura but without auricular crura. Dimensions (in mm):-- Remarks:— This species is named in honor of Dr. Warren O. ADDICOTT of the U.S. Geological Survey.
From the above mentioned morphological characteristics it is evident that this species should be assigned to the genus Mizuhopecten. It can be distinguished from Mizuhopecten yessoensis (JAY) by its small size, lack of radial threads on the auricles and the presence of intercalary threads in the interspaces between the radial ribs. Type locality:— U.S. Geol. Surv., Loc. No. M2978. West Fork of Wishkah River, Grays Harbor County, Washington. Montesano Formation. Early Pliocene. Associated fauna:— Yabepecten condoni (HERTLEIN).» KÔICHIRÔ MASUDA, 1971
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«Mizuhopecten warreni Masuda (PI. 4, figs. 2, 5), a moderately large species closely allied to Patinopecten, but lacking the auricular crurae of that genus (Masada, 1971), appears in the Wishkahan Stage (USGS loc. M2978 and Stanford University loc. NP 243) and ranges upward into the lower part of the Graysian Stage (USGS loc M1551). The right valve of this species resembles Yabepecten condoni (Hertlein) in having a similar rib count. The two can be differentiated by the more strongly developed ribbing on right valves of M. warreni. Moreover, the posterior segment of the growth lines on the right anterior ear of M. warreni are recurved toward the beak whereas on Y. condoni they are more nearly vertical and meet the hinge line at almost 90°.»
ADDICOTT, W. O. 1981. Significance of pectinids in Tertiary biochronology of the Pacific Northwest. Geological Society of America, Special Papers, 184: 17-38, pls. 1-4. [p. 24]
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Mizuhopecten warreni (Masuda); W. O. Addicott, 1981, Significance of pectinids in Tertiary biochronology of the Pacific Northwest, plate 4, figures 2, 5.
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«Description.— An incomplete left valve of a moderately small Patinopecten from the Montesano Formation of Weaver (1912) near Hoquiam, Washington, has imbricate lamellar microsculpture and rather subdued primary ribs with occasional fine interribs. These features suggest relationship to the Recent Japanese species P. yessoensis (Jay) and to the middle Miocene species P. propatulus from the Pacific Coast of the United States. However, the ribbing on the Montesano specimen is much weaker than on P. propatulus.
Discussion.— Poorly preserved specimens that seem to represent Patinopecten n. sp. are in a Stanford University collection from the middle Wishkah River about 14 miles north of Aberdeen, Washington (loc. N.P. 243). These specimens bear the manuscript name "Patinopecten pembertoni A. and H." [Arnold and Hannibal]. The pectinid reported from the same area (UW loc. 15) by Weaver (1916b, p. 216) as Pecten propatulus may be the same species. Chronostratigraphic data.— See under Nassarius hoquiamensis. Figured specimen.— USNM 649124. Occurrence.— USGS Cenozoic loc. M 1551. Cut along 22d Street, 300 to 400 feet north of intersection with Cherry Street, in NE ¼ NW ¼ sec. 12, T. 17 N., R. 10 W., Aberdeen quadrangle, Washington, and SU loc. N.P. 243. Montesano Formation of Weaver (1912). Late Miocene or early Pliocene.» ADDICOTT, W. O. 1966. New Tertiary marine mollusks from Oregon and Washington. Journal of Paleontology, 40 (3): 635-646, pls. 76-78. [p. 644]
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Patinopecten n. sp.; W. O. Addicott, 1966, New Tertiary marine mollusks from Oregon and Washington, plate 76, figure 8.
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