Lithopoma precursor

Geological Range

Late Pliocene to Middle Pleistocene; Extinct.

Paleogeographic Distribution

Southern Florida.

Remarks

Original Description (from Dall, 1892, p. 384-385):

"Pliocene marls of the Caloosahatchie and Shell Creek, Florida.

Shell elevated, subacute, eight-whorled; nucleus small, smooth, of a single whorl; subsequent whorls sculptured with numerous subequal, flexuous, spiral threads, with narrower interspaces, crossed obliquely by numerous elevated, imbricated incremental lamellae, so close-set that the entire surface when intact is densely scaly with minute flexuous, irregular scales; at right angles to the incremental lines the surface of the whorl is plicated from the suture forward with low irregular ridges, which frequently fail before reaching the periphery, and vary in number as well as in strength, generally being more numerous than the peripheral nodules; periphery rounded, pinched up into numerous (12 to 18) squarish nodules, with their vertical axes the longer, over which the smaller sculpture is continuous, and above which the whorl is somewhat contracted; base flattish, with four to six principal spirals and a narrow, elevated fasciole around the pillar, the whole covered densely with imbricated lamellae like those of the spire; pillar arched, narrow, with a groove behind it, and bituberculate at the base; aperture rounded quadrate, simple inside, the outer margin somewhat crenulated by the sculpture; the periphery of the whorls overhangs the suture, and its nodules are rarely spinose except near the apex. Alt. of shell 35; max. diam. 28 mm.

Operculum with the inner side flat and exhibiting four or five whorls with an impressed line parallel with the suture; the outer side convex, with a deep pit over the nucleus and the remainder of the surface showing six or seven strong spiral, granular ribs separated by narrower, deeply-cut grooves, terminating at the surface of increment."

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Stratigraphic Occurrences

Middle Pleistocene

Bermont Formation (S. FL)

Early Pleistocene

Caloosahatchee Formation (S. FL)

Late Pliocene

Tamiami Formation (Pinecrest Beds) (S. FL)