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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 46 (1962)

Issue: 2. (February)

First Page: 276

Last Page: 276

Title: Quantitative Study of Athleta Petrosa Stock in Eocene of Texas: ABSTRACT

Author(s): Peter U. Rodda, John W. Dietrich, W. L. Fisher

Article Type: Meeting abstract

Abstract:

Based on qualitative study of the gastropod genus Athleta in the Eocene of Texas, two species are recognized--Athleta tuomeyi Conrad, 1853, in the Wilcox Group, and A. petrosa (Conrad, 1833) in the Claiborne and Jackson Groups. A. petrosa is divided into four successional subspecies and three divergent subspecies.

A statistical study was made of about 1,500 specimens from 49 localities to provide quantitative confirmation of some of the qualitative conclusions. Five parameters were measured: height, maximum width, height of spire, number of columellar folds, and number of spines on the body whorl. A program was prepared for the Control Data Corporation 1604 Computer for the calculation of 20 combinations (sums and ratios) of the parameters of each individual and for the calculation of mean and standard deviation of each parameter and combination by localities. More than half of the combinations appear to be significant.

A distinct separation of A. tuomeyi is shown in several significant computations. Mixtures of successional and divergent subspecies of A. petrosa are apparent. Within the successional subspecies, there is a rapid change in measured and significant computed values from the Reklaw subspecies to the Weches subspecies, very little change from the Weches subspecies to the Cook Mountain subspecies, and a rapid change from the Cook Mountain subspecies to the Jackson subspecies. Geographic variation generally is insignificant.

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