Abstract

Two new species of Ringicula (Ringicula), R. codellana and R. augusta, and a third distinct form, R. sp. A, occur in the "Pugnellus sandstone" of Huerfano Park, S.-central Colorado. These are the first representatives of Ringicula noted from the Colorado Group of the western interior. The denticulate inner edge of the outer lip on R. codellana indicates that this species, and possibly all 3 forms, belong to the subgenus (Ringicula). They are all atypical of this subgenus in being elongate and smooth shelled. The presence of Ringicula in the "Pugnellus sandstone" fauna reinforces the sublittoral, semi-tropical to tropical ecological assignment of this assemblage. In Huerfano Park, as at the type area, the Carlile Shale is divisible into the Fairport, Blue Hill, and Codell members, in ascending order. The Codell member in Huerfano Park consists of a lower sandstone unit, the "Pugnellus sandstone," of late middle Turonian age (zone of Collignoniceras and middle limestone and upper shale units of early upper Turonian age (zone of Prioncyclus wyomingensis). The upper shale is discontinuous, and is an unusual feature of the Codell Sandstone Member. Throughout much of its range in Colorado and Kansas, the Codell Sandstone Member has yielded only an upper Turonian fauna which occurs in limestone and calcareous sandstone near the top of the section. On the basis of its fauna, some authors have correlated the "Pugnellus sandstone" with late middle Turonian Blue Hill Shale Member. Others have correlated it with the lithologically similar sandstones of the lower Codell Sandstone Member. We favor the latter interpretation and present evidence that the lower sandstone unit of the Codell Sandstone Member is of late middle Turonian age over much of central and S.-central Colorado.

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