Degree Name

MS (Master of Science)

Program

Geosciences

Date of Award

5-2015

Committee Chair or Co-Chairs

Blaine Schubert

Committee Members

Steven Wallace, Jim Mead

Abstract

The American alligator, Alligator mississippiensis, is a large extant archosaur and member of the Order Crocodilia. Crocodilian ontogeny has been studied in great detail, the skull being of particular interest. One aspect of the skull left unstudied is how individual cranial elements change through ontogeny independent of one another. This study observed morphological change in a growth series of 34 specimens of A. mississippiensis from ETSU Vertebrate Paleontology Lab collections. The premaxilla, maxilla, nasal, jugal, frontal, and parietal were analyzed using landmark morphometrics. The frontal, jugal, and parietal showed more allometric growth with the orbits reducing in size posteriorly. The premaxilla, maxilla, and nasal showed more isometric growth. This suggests the common observation that the snout elongates with age is mistaken. The cranium showed allometric growth in very early in life but more isometric growth after that. Unique to this study, the premaxilla showed almost no shape change throughout ontogeny.

Document Type

Thesis - Open Access

Copyright

Copyright by the authors.

Included in

Paleontology Commons

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