Date of Award

12-1982

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Judith A. Schiebout

Abstract

This study is a paleoecological and functional morphological analysis of the Archaeoceti based on a specimen of Basilosaurus cetoides. The specimen, Louisiana State University Museum of Geoscience Vl, was collected at Montgomery Landing, Grant Parish, Louisiana from the upper Eocene Yazoo Clay (Jackson Group). The specimen consists of the skull, mandibles, cervical vertebrae, upper thoracic vertebrae, ribs and forelimbs.

The skull of LSUMG Vl has an interparietal bone, pterygoid bones which form a pterygoid fossa, and a well developed falciform process of the squamosal which is in contact with the pterygoid bone. The auditory ossicles of B. cetoides are similar in form to those of Dorudon osiris. The malleus probably retained a functional manubrium, a primitive feature for the Cetacea. The stapes retained an intercrural aperture. The incus is similar to Globicephalus.

The forelimbs in B. cetoides show features that would allow them to be used in locomotion. The greater tuberosity and deltoid crest of the humerus, olecranon of the ulna, and anterior crest of the radius would serve as attachment sites for important muscles that would function in locomotion. The method of locomotion would be similar to that employed by Zalophus californianus and would entail a power stroke of flexion, adduction, and protonation, and a recovery stroke of extension, abduction, and supination.

The vertebrate and invertebrate fauna in the surrounding sediments indicate a quiet marine shelf environment with sporadic sedimentation. The bones served as an encrusting site for ectoprocts, and bivalves. Otoliths of teleost fishes in the associated sediments are believed

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