Master's Theses

Date of Award

Fall 1994

Degree Name

Master of Science (MS)

Department

Geosciences

Advisor

Richard Zawerksi

Abstract

Most extinct modern- level elasmobranchs, including most selachians from the Upper Cretaceous deposits of Kansas, are known only from isolated teeth. However, some specimens of the extinct shark, Cretoxyrhina mantelli (Lamniformes: Cretoxyrhinidae), represent reasonably complete individuals. Unlike studying isolated teeth, examination of associated skeletal and dental elements, combined with taphonomic and biostratigraphic data, provides robust information about the paleobiology of C. mantelli. The neurocranial structure, calcification pattern of centra, vertebral count, and dental formula indicate that C. mantelli is a valid taxon. The scale morphology suggests that C. mantelli was a fast swimming pelagic shark. The total body length of a large C. mantelli is estimated to be 4.5 to 5 m, but very large individuals probably reached about 5.5 m. Synthesis of all anatomical information suggests that the body form of C. mantelli resembled that of extant Carcharodon carcharias or Lamna nasus, whereas the feeding mechanics of Cretoxyrhina mantelli was probably similar to that of extant Isurus. Because some cretoxyrhina specimens provide evidence of ingestion of large active vertebrates (including teleosts, mosasaurs, and possibly plesiosaurs), C. mantelli most likely occupied the apex of the food chain; however, it was probably consumed frequently by anacoracids after death. C. mantelli is characterized herein as an offshore shark.

Rights

Copyright 1994 Kenshu Shimada

Comments

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