Syncyclonema inconspicuus (Cragin, 1894)
CRAGIN, F. W. 1894. Descriptions of new species of invertebrata from the Comanche Series in Texas, Indian Territory, and Kansas; with definition of two Comanche Terranes. Colorado College Studies, 5. Annual publication, Colorado Springs, Colo., 1894. [p. 51]
1894 Pecten inconspicuus Cragin, 1894
Pecten inconspicuus Cragin; W. S. Adkins, 1920, The Weno and Pawpaw formations of the Texas Comanchean, plate 11, figure 4.
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«Shell small, thin, subcircular, a trifle higher than long, slightly truncated anteriorly and posteriorly, right valve gently convex, its outer surface smooth except for faint con centric strise and a few remote, subimbricate growth-lines; umbonal angle sharp at apex, nearly a right angle; anterior ear (imperfect in the type) reentrant below, as indicated by the direction of the strise upon it, outline of posterior ear making an obtuse angle, its posterior margin rather more than one and a half times as long as its dorsal. Left valve unknown.
Measurements. — Height 9.5, length 8.75, convexity of left valve 1 mm. Occurrence. — On slope of Pawpaw creek, east of Denison, Texas, in red ochraceous shell-conglomerate of the Pawpaw clays. The associate fossils are Ostrea quadruplicata, Tapes dentonensis, Yoldia microdonta, Turritella seriatim-granulata, Sphenodiscus, Turrilites, etc.» FRANCIS WHITTEMORE CRAGIN, 1894
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«As noted by Hayami (1965: 314), Cretaceous ‘Entoliidae’ consist mainly of syncyloneminine species. Examples are: (a) the type species of Syncyclonema,which has distinct commarginal plicae developed mainly on its right valve; (b) forms having nearly smooth exteriors that are similar to or the same as Pectinella, such as Pecten inconspicuus Cragin, 1894 from the Lower Cretaceous (Albian) of Texas; and (c) most of the species described by Dhondt (1971) under the name Syncyclonema.»
WALLER, T. R. 2006. Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record. Zoological Journal of the Linnean Society, 148: 313-342, figs. 1-12. [p. 326, 327]
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«Shell small, subcircular to ovate in outline, compressed, subequivalve; ears relatively large, triangular with the external angles rounded; anterior ear larger and differing in form from the posterior ear, and in the right valve having a small, distinct byssal notch; surface almost smooth but showing under a lens numerous very fine growth lines, which are coarser and more prominent on the ears, especially near the line of their junction with the body of the shell. Some specimens also show somewhat more prominent concentric sculpture near the beak and a few distant, impressed growth lines at later stages. In a few examples, traces of minute, radiating sculpture consisting of curved striae like those of Camptonectes, were detected.
A specimen somewhat larger than the average measures 12 mm. in height and 11 mm. in length. The convexity of both valves united is not more than 2 mm. Types: 3 cotypes, U.S.N.M. 32684; plesiotypes, 103214a-c, 103215a-b. Locality and position: The types were obtained in the Pawpaw formation on 4he east slope of Pawpaw Creek near Denison in Grayson County, Tex., where the species is abundant. The species also occurs sparingly in the Kiowa shale near Belvidere, Kans., and a few imperfect molds that may belong to it have been collected in the Washita group near Kent and El Paso in western Texas. It is recorded from the Weno day of Grayson and Cooke Counties, Tex. (Adkins, 1920, p. 124).» STANTON, T. W. 1947. Studies of some Comanche pelecypods and gastropods. United States Geological Survey Professional Paper, 211: 1-256, pls. 1-67. [p. 40]
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Pecten (Syncyclonema) inconspicuus Cragin; T. W. Stanton, 1947, Studies of some Comanche pelecypods and gastropods, plate 15, figures 1-9.
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