Nodipecten peedeensis (Tuomey & Holmes, 1855)
TOUMEY, M. & F. S. HOLMES. 1855-1856. Pleiocene fossils of South Carolina. Russell and Jones, Charleston, South Carolina, 152 p. [p. 30, pl. 12, figs. 1-5]
1855 Pecten peedeensis Tuomey & Holmes, 1855
1914 Pecten (Nodopecten) [sic] vaccamavensis Olsson, 1914
1914 Pecten (Nodopecten) [sic] vaccamavensis Olsson, 1914
M. Tuomey & F. S. Holmes, 1855-1856, plate 12.
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«P. testa trigono-ovata, crassa, aequilaterali; costis 8, ampliter nodosis, concentrice striatis, sub-squamosis.
DESCRIPTION. Shell triangularly ovate, somewhat flatly convex, equivalve, equilateral; with eight large knobbed ribs, the whole concentrically covered with squamose striae, Lower valve with the ribs generally dislocated vertically, and rather abruptly on the umbones. The interstices between the ribs become very wide towards the pallial margin. The upper valve with ribs strongly knobbed. Of all the fossil PECTENS this is the thickest and most robust. It was first observed by Mr. Ruffin, on the Pee Dee, and the name is that by which he designated it. It is very closely related to, if not identical with P. NODOSUS, of the Gulf of Mexico. In the recent shell, the whole surface is marked by strongly impressed radiating lines, whilst in the fossil the surface is covered by radiating and transverse striae.
LOCALITY. Darlington District.
Museum, College of Charleston, S. C.»
M. TOUMEY & F. S. HOLMES, 1855
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«Description: Shell large, subcircular, well inflated; ribs high, nodes large; upper valve with seven large, prominently noded ribs, alternating in strength, lower valve with eight subequal ribs, nodes rare or absent. Secondary sculpture of coarse radial threads crossed by finer concentric lines. Concentric resting stages often stepped or shelved.
Occurrence: Pliocene. Carolinas – upper Goose Creek Limestone. Type locality: Near Giles Bluff, Pee Dee River. South Carolina. Discussion: Nodipecten peedeensis was originally cited (Tuomey, 1848) as occurring with two lower to mid-Pliocene taxa, Chesapecten septenarius and Ecphora quadricostata (Campbell et aI., 1975, p. 82, 110; Blackwelder, 1981, p. 3). The type specimens of N. peedeensis were temporarily misplaced in the American Museum of Natural History. In their absence, Tucker-Rowland (1938, p. 23) designated a misidentified European specimen as neotype (Smith, 1988, personal communication).
Two morphologies exist within the Goose Creek Limestone material now at hand: a smoother, less sculpted shell typified by the Berkeley quarry population (over 200 specimens); and shells from the Mason Dixon pit, Conway, South Carolina, with higher ribs, somewhat stronger secondary sculpture, and higher and more frequent nodes. In addition to the stronger sculpture, the Mason Dixon specimens are very large, sometimes exceeding 160 mm in maximum diameter. The Mason Dixon population also includes abnormal morphologies, which we intrepret as genetic mutants. The weaker ribs of the mutant left valve are reduced or eliminated, producing five instead of seven ribs, and the right valve correspondingly has the four central ribs fused into two wide ribs. A small population from the Charleston area has similar normal and mutant morphologies. M. Campbell (1988a, 1988b) first interpreted the Charleston and Berkeley quarry populations as variation within a single species. With the 1989-1990 discovery of a large population (over 120 specimens) of N. peedeensis from the Mason Dixon pit, we now conclude that two species-level taxa are involved. The Berkeley Quarry specimens best conform with N. collierensis (Mansfield), but the Mason Dixon and Charleston specimens better conform with the holotype of N. peedensis. A detailed morphological study is in progress.» CAMPBELL, M. R. & L. D. CAMPBELL. 1995. Preliminary Biostratigraphy and Molluscan Fauna of the Goose Creek Limestone of Eastern South Carolina.Tulane Studies in Geology and Paleontology, 27 (1-4): 53-100, pls. 1-5. [p. 80]
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Nodipecten peedeensis (Tuomey and Holmes); M. R. Campbell & L. D. Campbell, 1995, Preliminary Biostratigraphy and Molluscan Fauna of the Goose Creek Limestone of Eastern South Carolina, plate 3, figure 2.
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