Lyriochlamys complexicosta (Gabb, 1869)
GABB, W. M. 1866-1869. Paleontology of California. Vol II. Cretaceous and Tertiary fossils. Geological Survey of California, 299 p., pls. 1-36. [p. 199, pl. 33, fig. 97, 97a]
1869 Pecten complexicosta Gabb
W. M. Gabb, 1866-1869, plate 33.
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«SHELL moderate in size, thin, equivalve, nearly equilateral; sides and base forming a regular curve, slightly elongated; the right side of the upper valve, and corresponding side of the lower, a little the most convex above; upper valve with the left ear a little concave on its lateral margin; shape of the right ear unknown; right ear of lower valve narrow, produced, and deeply emarginate. Surface marked by about twelve or fourteen radiating ribs, with sometimes an equal number of smaller ones intercalated; these are more strongly marked on the cast than externally; besides the ribs, the entire surface is closely sculptured by minute radiating lines, very variable in size.
Figure, natural size, and a magnified view of the surface.
Common in the white limestone of the Shasta Group in Morgan Valley, south of Clear Lake, collected by Professor Whitney. Although the species is abun dantly represented at this locality, no entire specimens have ever been obtained, owing to the character of the matrix. By the study of a large number of fragments, I have been enabled to arrive at nil the important specific characters, except the shape of the ear, which is represented broken in the figure, as it occurs in the best specimen. Two or three casts before me give the outline, and the details of the surface are drawn from impressions in the matrix.» WILLIAM MORE GABB, 1869
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«Material and occurrence. Six specimens from Rocky Creek (probably Valanginian, Early Cretaceous), up to 68 mm in height. Stanton’s (1895) figured specimens (USNM 23028 and 23102) were not found in the USNM type collection during a visit in November 2012, but many specimens from Hauterivian (Early Cretaceous) Wilbur Springs seep site (which is located near the Bear Creek seep site reported here; see description of locality #5 in Kiel et al. (2008a) for details) were seen in the non-type collection.
Remarks. Gabb’s (1869) specimens are from ‘Morgan Valley south of Clear Lake’ (Stanton 1895, p. 37), which is a wide area that also encompasses the Rocky Creek site where the present material was collected. Stanton’s (1895) specimens are from Wilbur Springs, thus the species is widely distributed among Early Cretaceous seep deposits in California. Both at Rocky Creek and at Wilbur Springs the specimens occur in clusters in which several specimens were stacked upon each other in random orientation. At Wilbur Springs they were also closely associated with the brachiopod Peregrinella whitneyi. Other pectinids at Cretaceous seep deposits include a rare Propeamussium at the Early Cretaceous seeps deposits in the Kuhnpasset beds in Greenland (Kelly et al. 2000) and a rare ‘Pecten sp.’ at the potential seep site ‘Koniakauer Schloß’ in Czech Republic (Ascher 1906, cf. Kiel & Peckmann 2008, Kaim et al. 2013b) which appears to have finer, more numerous, and more closely spaces radial ribs than Lyriochlamys complexicostata [sic] (see Ascher 1906, pl. 14, fig. 1).»
KAIM, A., R. G. JENKINS, K. TANABE & S. KIELL. 2014. Mollusks from late Mesozoic seep deposits, chiefly in California. Zootaxa, 3861 (5): 401-440, figs. 1-18. [p. 427, 428]
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Lyriochlamys complexicostata [sic] (Gabb, 1869); A. Kaim, R. G. Jenkins, K. Tanabe & S. Kiell, 2014, Mollusks from late Mesozoic seep deposits, chiefly in California, figure 14.
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«The species is abundant, associated with Rhynchonella whitneyi and Modiola major, in the white limestone at Wilbur Springs, on Sulphur Creek, Colusa County, Cal. The ears are large and triangular, and the byssal notch of the right valve is broad and comparatively shallow. The left valve is perceptibly more convex than the right. None of the specimens from this locality shows the minute radiating lines mentioned in the description; nor are they shown in the original restored figure, excepting in a magnified view of a portion of the surface. Fragmentary specimens recently collected by Mr. Jasper Palmer, jr., of Reiff, Cal., at or very near the original locality, have this fine radiating sculpture well developed. Possibly the specimens from Wilbur Springs should be separated as a variety, but they agree so closely in all other respects that it seems probable that the absence of the fine lines is due to the state of preservation. They are all more or less in the forrn of internal casts, none preserving the outer surface of the shell. An average specimen measures 50 mm. in height, 44 mm. in greatest length, 17 mm. on the hinge line, and 14 mm. in convexity of both valves united.»
STANTON, T. W. 1895. Contributions to the Cretaceous paleontology of the Pacific coast. The fauna of the Knoxville beds. United States Geological Survey Bulletin, 133: 132 p., pls. 1-20. [p. 37, 38]
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Pecten complexicosta Gabb; T. W. Stanton, 1895,
Contributions to the Cretaceous paleontology of the Pacific coast. The fauna of the Knoxville beds, plate 2, figures 7-9. |