Title page for ETD etd-04122010-170915


Type of Document Master's Thesis
Author Hagge, Mark Daniel
Author's Email Address mhagge2@lsu.edu, mark_hagge@hotmail.com
URN etd-04122010-170915
Title A Functional and Ontogenetic Skull Analysis of the Extant Rhinoceroses and Teleoceras major, an Extinct Miocene North American Rhinoceros
Degree Master of Science (M.S.)
Department Geology & Geophysics
Advisory Committee
Advisor Name Title
Schiebout, Judith Committee Chair
Anderson, Laurie Committee Member
Dutrow, Barbara Committee Member
Homberger, Dominique Committee Member
Keywords
  • morphology
  • grazer
  • browser
  • geometric morphometrics
  • feeding
  • ecology
  • function
  • extant
  • Teleoceras
  • skull
  • development
  • ontogeny
  • rhinoceros
Date of Defense 2010-02-02
Availability unrestricted
Abstract
Functional and ontogenetic skull differences among extant rhinoceroses and the extinct North American rhinoceros Teleoceras major were investigated to assess the unknown feeding ecology of Teleoceras. Ontogenetic skull sequences of the extant Indian rhino (Rhinoceros unicornis), Sumatran rhino (Dicerorhinus sumatrensis), white rhino (Ceratotherium simum), and black rhino (Diceros bicornis), and the extinct Miocene North American rhino T. major were gathered for both qualitative and quantitative assessments. Eleven functional characters related to specific feeding ecologies in extant perissodactyls were morphologically described, and each speciesí skull development was described in detail. Nineteen linear skull measurements were taken across all specimens of all ages to statistically investigate functional and developmental differences among the species. Specimens were also photographically documented for geometric morphometric analyses of ontogenetic shape transformations. Functional character results indicated that T. major was likely a grazer based on its high number of grazing characters, such as its large posterior maxilla, broad jugal, and strong mandibular angle. Teleoceras major and the extant grazer C. simum also shared grazing character states, such as an anterior jugal extension, a low occiput, and a deep mandibular body. Ontogenetic comparisons revealed both shared and distinct patterns among the species. The rhino species all shared early cranial lengthening, similar timing in horn and tusks development, and strong adult development of the masseter and temporalis attachment areas. Distinctions in the speciesí ontogenies are in the occiput, zygomatic arch, mandibular angle, and mandibular body, which are all characters related to feeding ecology. Early development of masseter attachment areas in T. major and the temporalis attachment areas in C. simum are understood as differing adaptations to grazing feeding ecologies.
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