T. S. Dyman

Publication Date

1973

Document Type

Dissertation/Thesis

First Advisor

Frost, Stanley H., 1939-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geology

LCSH

Foraminifera; Fossil--Venezuela; Lepidocyclina

Abstract

A statistically large sample of Lepidocyclina (Lepidocyclina) sp. from the upper orbitoid beds of the Punta Canero Group, at Punta Mosquito, Isla de Margarita, Venezuela, was analyzed to determine the amount and nature of morphologic variation, and to evaluate present lepidocyclinid taxonomy in light of the results. More than 250 thin sections were prepared and measured for as many as 26 variables in equatorial section and 14 variables in vertical section. Both-equatorial and vertical sections were analyzed using univariate and bivariate statistical analyses as well as Q-and R-mode factor analysis and discriminant analysis of two groups. Results show that the range of morphological variation is large and the importance of genetic and environmental factors can only be speculated. High correlation coefficients between some variables and the grouping of variables into factors indicate redundancy in the overall variable set. This suggests that future studies of this type may be made using fewer variables without sacrifice of major portions of the information. It is necessary to use multivariate statistics to classify lepidocyclinids when such large morphologic variation exists. Previous classifications based oil only a few variables are inadequate in light of the large degree of uncorrelated morphologic variation in some samples. The most adequate classification scheme should be based on a wide range of morphologic features of the test, analyzed by computer techniques. Morphologic differences in L. (L.) pustulosa and L. (L.) macdonaldi forms found in the sample were not great enough to warrant classifying them as separate species. The differences are in fact gradational, and the intermediate forms were impossible to objectively classify.

Comments

Includes bibliographical references.||Includes illustrations.

Extent

viii, 97 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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Text

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