Spondylus carlosensis Anderson, 1905
ANDERSON, F. M. 1905. A stratigrafic study in the Mount Diablo Range of California. Proceedings of the California Academy of Sciences [3th Series], Geology, 2 (2): 155-248, pls. 13-35. [p. 194, pl. 13, fig. 1]
1905 Spondylus carlosensis Anderson, 1905
F. M. Anderson, 1905, plate 13.
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«Shell of medium size, sub-circular or obliquely ovate, radially ribbed, convex; costae granulated or obscurely spinose; ears and hinge rather broad. The costae radiate in graceful, sinuous lines from the beak to the margins, and occur in pairs or triplets, every second or third rib being inore elevated than the others.
Occurrence.— This species occurs only rarely in the Avenal Sands west and north of Coalinga.»
FRANK MARION ANDERSON, 1905
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«REMARKS. Two specimens were found. One is small (height 20 mm), closed valved, and well-preserved overall. This specimen affords new morphologic information because, unlike previously described and illustrated specimens of this species, it shows both the left (Fig. 52) and right (Fig. 53) valves rather than only the left valve. The right (attached) valve is less circular and much more convex than the left. The radial ribs on the right valve are less closely spaced, wider, less sharp sided, and more spinose than those on the left. Usually, every fourth or fifth radial rib on both valves (especially on the right valve) is more prominent than the other ribs. Although the auricles are mostly missing on the right valve, those on the left valve are intact (a rare condition). The auricles on the left valve are small, and the anterior one has coarse growth lines and two strong and wide radial ribs, one of which delineates the hinge-line. The posterior auricle on the left valve is smooth, but it is set off from the rest of the valve by a moderately strong radial rib. On both valves, the beak is anterior of the valve center.
The other specimen of Spondylus carlosensis found at CSUN locality 1343 is a portion of a right valve attached to a specimen of the solitary coral ?Antillophyllia californica new species. The presence of Spondylus carlosensis in the upper 100 m of the Santa Susana Formation is the first record of this species from "Meganos Stage" strata.» SQUIRES, R. L. 1999. Upper Paleocene to Lower Eocene ("Meganos Stage") marine megafossils in the uppermost Santa Susana Formation, Simi Valley, southern California. Contributions in Science, 479: 1-38, figs. 1-68. [p. 24]
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Spondylus carlosensis Anderson, 1905; R. L. Squires, 1999, Upper Paleocene to Lower Eocene ("Meganos Stage") marine megafossils in the uppermost Santa Susana Formation, Simi Valley, southern California, figures 52, 53.
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«Supplementary description.— "The left valve figured is irregular in outline. There is a well-marked regular umbonal area of development during the period preceding attachment. The sculpture consists of irregular, sharp, round-topped ribs of varying strength, usually large ribs alternating with smaller ones, with approximately nine more prominent noded ribs subequally spaced over the surface of the valve. The ears have been broken.
"The hinge shows long auricular crurae, buttressed ventrally by two ridges. The ligamental groove is long and narrow, extending to the apex; the crural sockets are subtriangular, set beneath the umbonal ends of the crurae." (Vokes, 1939, p. 57) Comparison.— "Spondylus cliffensis *** is a smaller species and appears to be characterized by the possession of a longer hinge-line." (Vokes, 1939, p. 57). Geographic range.— Middle and southern California. Geologic range.— Eocene. Occurrence in California.— Eocene: Avenal Sandstone (Stewart, 1946), Domengine and Tejon Formations (Vokes, 1939), and Cozy Dell Shale (Weaver and Kleinpell, 1963).» MOORE, E. J. 1987. Tertiary Marine Pelecypods of California and Baja California: Plicatulidae to Ostreidae. United States Geological Survey Professional Paper, 1288-C: C1-C53, pls. 1-34. [p. C7]
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Spondylus carlosensis Anderson; E. J. Moore, 1987, Tertiary Marine Pelecypods of California and Baja California: Plicatulidae to Ostreidae, plate 1, figures 5.
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«The left valve figured is irregular in outline. There is a well-marked regular umbonal area of development during the period preceding attachment. The sculpture consists of irregular, sharp, round-topped ribs of varying strength, usualljr large ribs alternating with smaller ones, with approximately nine more prominent noded ribs subequally spaced over the surface of the valve. The ears have been broken.
The hinge shows long auricular crurae, buttressed ventrally by two ridges. The ligamental groove is long and narrow, extending to the apex; the crural sockets are subtriangular, set beneath the umbonal ends of the crurae. The hinge figured by Anderson & Hanna (1925: text-f. 10) shows none of the characters of the genus and is wholly unsatisfactory for purposes of identification. Spondylus cliffensis M. A. Hanna (1927: 278. pl. 32, f. 2, 7)* is a smaller species and appears to be characterized by the possession of a longer hinge-line.» * La Jolla formation.
VOKES, H. E. 1939. Molluscan faunas of the Domengine and Arroyo Hondo Formations of the California Eocene. Annals of the New York Academy of Sciences, 38: 1-246, pls. 1-22. [p. 57]
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Spondylus carlosensis Anderson; H. E. Vokes, 1939, Molluscan faunas of the Domengine and Arroyo Hondo Formations of the California Eocene, plate 3, figures 10, 13.
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