Chesapecten sayanus (Dall, 1898)
DALL, W. H. 1898. Contributions to the Tertiary fauna of Florida. Silex Beds of Tampa and the Pliocene Beds of the Caloosahatchie River. Part IV. I. Prionodesmacea: Nucula to Julia. 2. Teleodesmacea: Teredo to Ervilia. Transactions of the Wagner Free Institute of Science of Philadelphia, 3 (4): viii, 571-947 p., pls. 23-35 (pls. 36 and 37 in part 5, 1900). [p. 725, pl. 26, fig. 6]
1898 Pecten (Lyropecten) madisonius var. sayanus Dall, 1898
W. H. Dall, 1898, plate 26.
|
«Upper Oligocene (Alum Bluff beds) of Oak Grove, Santa Rosa County, Florida; on the Chattahoochee River at Old Chattahoochee Landing, at Rock Bluff, and on the Chipola River in the Chipola beds.
This form is the percursor in the Upper Oligocene of the typical Madlsonius of the Miocene. It differs from the latter in its extreme compression, the ribs, except in the umbonal region, being almost obsolete. Alt. 120, lat. 135, diam. about 16 mm. This is what has been referred to Jeffersonius and Madisonius by L. C. Johnson, Foerste, and other observers in the Floridian Oligocene. The characteristics of P. Madisonius have been pointed out under P. Jeffersonius, from which it differs by its more compressed shell, more numerous ribs, and coarser and more scabrous sculpture, as well as the deeper and wider byssal notch. The young rarely have the scales continuous across the tops of the ribs.» WILLIAM HEALEY DALL, 1898
|
«Discussion.— The most abundant species of pectinids at the Pollack Farm Site is a fairly large Chesapecten that is characterized by numerous scaly ribs that are prominent during the early stages of development, but gradually become less elevated in the adults to the point that the disk is nearly flat in many specimens. The entire disk is covered by rows of very fine scales. In this regard, the species closely resembles “Pecten madisonius sayanus,” described by Dall (1898) from the Oak Grove in western Florida and is here considered to be that species. A single valve of C. sayanus was found by the author in Bed 10 of the Plum Point Marl at Camp Roosevelt, Calvert County, Maryland. The only other specimens known to the author are several collected by Julia Gardner from Wye Island, Maryland, and a number of individuals collected by the author from the Pungo River Formation at the Lee Creek Mine, Aurora, North Carolina.
This appearance of Chesapecten in the early Miocene marks the first known occurrence of that taxon. Geologic range.— Kirkwood Formation; Calvert Formation, Plum Point Marl Member (Bed 10); Pungo River Formation.» WARD, L. W. 1998. Mollusks from the Lower Miocene Pollack farm site, Kent County, Delawere: a preliminary analysis. In: R. N. Benson, ed., 1998, Geology and paleontology of the lower Miocene Pollack Farm Fossil Site, Delaware: Delaware Geological Survey Special Publication No. 21, p. 59–131. [p. 80]
|
Chesapecten sayanus (Dall); L. W. Ward, 1998, Mollusks from the Lower Miocene Pollack farm site, plate 11, figures 3-5.
|