[accordions title=”” disabled=”false” active=”1″ autoheight=”false” collapsible=”true”] [accordion title=”Taxonomic Details”] Formerly: Loxoplocus bowdeni Taxonomic Note: The genus for L. bowdeni has been moved multiple times between Paupospira – Loxoplocus – Lophospira. According to P.J. Wagner, 2013, the correct taxonomic genus is Paupospira. However in the Cincinnatian grouping, it is commonly called Loxoplocus.
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Cincinnatian gastropods sometimes are found in great abundance in thin beds – almost to the exclusion of other fossils. Although such beds occur in many units in the section, two occurrences deserve special note. One is within the Miamitown Shale, which is Maysvillian in age, and the other is the Marble Hill Bed (Richmondian) (Figure 9.4). The Miamitown Shale is a thin, shale-dominated formation that attains a maximum thickness of five meters at Miamitown, near the Great Miami River, and thins to less than one meter near Cincinnati (Dattilo 1996). Within the Miamitown is a layer, nicknamed the “gastropod shale,” about 1.5-2 meters thick, characterized by abundant molluscs, including pelecypods, the monoplacophoran Cyrtolites, and gastropods (Figure 9.4A). Near the top of this interval is a thin limestone that is packed with gastropods, mostly of Paupospira bowdeni (referred to Loxoplocus in older literature), preserved as internal molds. The so-called “gastropod shale,” along with the thin limestone, can be traced from Miamitown, in Ohio, to northern Kentucky, a distance of 20 km. The paleoenvironmental significance of the snail-rich Miamitown bed is not entirely clear. The overlying Bellevue Limestone, with its thin, wavy beds containing large brachiopods and bryozoans, indicates very shallow water, shoaling conditions. Thus the Miamitown could represent a slightly deeper environment, perhaps lagoons sheltered between shell-rich shoals of the Bellevue. Organic-rich muds that accumulated in the lagoons could have provided a habitat favorable for snails, but hostile to filter-feeding brachiopods and bryozoans.
The Marble Hill Bed is another remarkable occurrence of gastropods, in which limestone lenses up to about one meter thick are packed with specimens of three species of gastropods, Paupospira bowdeni, P.tropidophora (Meek), and P. moorei (Ulrich) (Felton, pers. comm.; Figure 9.4B). This bed occurs near the top of the Cincinnatian in the Rowland member of the Drakes Formation (following stratigraphic nomenclature adopted in Kentucky; this is approximately equivalent to the top of the Waynesville Formation as used in other literature). The Marble Hill Bed is exposed near Bedford, in Trimble County, Kentucky, and adjacent southeastern Indiana (Haattin et al. 1961; Swadley 1979). Like the Miamitown snail bed, the Marble Hill Bed lies in close stratigraphic proximity to rocks of very shallow water depositional environments. Swadley (1979) interpreted the Marble Hill Bed as a complex of offshore shoals and tidal-channel deposits along the margin of a shallow lagoonal area adjacent to intertidal mudflats.
Ruedemann (1926) (in reference to Foerste, 1916):
Apical angle averaging about 27 degrees; volutions eight to ten; peripheral angle only moderately prominent. Upper slope of whorls obscurely carinated near the suture, but more or less concave between this carination and the peripheral band. Along the lower side of the body whorl is another carination, usually obscure and never sharp. Umbilicus minute, usually more or less covered by the reflexed inner lip of the aperture. Surface striae curving backward into a strong V-shaped notch at the peripheral band.
Miller (1919):
The Waynesville (J.M. Nickles, 1903) is an argillaceous, thick-bedded limestone with shale, aggregating forty-five feet in thickness. It was named from an Ohio locality. It is rather poor in fossils. The most characteristic are the globular bryozoan, Cyphotrypa clarksvillensis, the gastropod Lophospira bowdeni, and the brachiopods Catazyga headi, Dalmanella jugosa, and Strophomena planumbona. We also find here the honeycomb coral Columnaria alveolata – a recurrence from the Cynthiana.
Ulrich & Scofield (1897):
Hight (sp?) 40 to 70 mm., usually 45 to 50 mm.; apical angle of Tennessee types of species averaging about 27° but varying between the extremes of 26° and 30°; of the Lorraine group variety 30° to 34°; of the Richmond group form 25° to 28° for specimens from Trimble county, Kentucky, and 27° to 33° for those from Boyle county in the same state; volutions eight to ten, moderately angular, the peripheral band thick, convex, varying as to prominence, situated beneath the center of the whorls; upper slope convex, sometimes obscurely carinated, in the upper half, more or less concave in the lower half; lower carina obscure, never sharp, often indistinguishable, the space above it to the peripheral carina generally a little concave; a minute umbilicus usually present, though in narrow specimens it is commonly covered by the reflexed inner lip; aperture subtriangular or irregularly quadrate, the outline depending upon the angle at which it is viewed; inner lip nearly vertical, generally exhibiting a small channel in its lower part. Surface with obscure undulations or unequal lines of growth. These are very strongly recurved toward the peripheral band, indicating a large and deep V-shaped notch in the outer lip. The band is distinctly convex, occasionally subangular in the middle, has obscure lunulae, and is bordered on both sides by a delicate raised line.
The prominence of the peripheral band varies considerably. As a rule it is the most pronounced in specimens from the Richmond group and at least in those obtained from the “Upper Nashville” of Tennessee and the Lorraine of Kentucky and Ohio. The apical angle also is variable through fairly constant in specimens from a given locality and horizon. The Lorraine variety is the widest, the Trimble county Kentucky, and Tennessee specimens are narrowest. The latter look like our fig. 42 only not so angular. Fig. 40 is perhaps a fair average for the species.
