Chesapecten madisonius

Geological Range

Early Miocene to Early Pleistocene; Extinct.

Paleogeographic Distribution

Southern Florida to Maryland.

Remarks

Original Description (from Say, 1824, p. 134-135):

"Much compressed, with about sixteen striated ribs.

Description. Shell rounded, much compressed; the whole surface covered with scaly striae: ribs elevated, rounded, with about three strife on the back of each; intervening grooves rather profound: ears equal, sinus of the ear of the superior valve profound, extending at least one third of the length of the ear.

Length rather more than four inches and a half; breadth four inches and four-fifths.

In magnitude this shell is justly entitled to compare with the preceding; but it differs in being much less convex, and in having a much more profound sinus in the ear of the superior valve. Three specimens, from which the above description was taken, belong to the Academy, and were presented by Mr. Watson."

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Stratigraphic Occurrences

Early Pleistocene

Chowan River Formation (VA)

Late Pliocene

Duplin / Raysor formations (GA)

Raysor Formation (GA)

Tamiami Formation (S. FL)

Yorktown Formation (VA)

Middle Miocene

Choptank Formation (VA) (Age not resolved beyond "Miocene")

Early Miocene

Calvert Formation (MD)

Calvert Formation (Plum Point Member) (MD)