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 - unrestricted
Recommended Citation
Harris, William Henry, "Ontogenesis in the Cranium of Alligator mississippiensis Based on Disarticulated Cranial Elements" (2015). Electronic Theses and Dissertations. Paper 2492. https://dc.etsu.edu/etd/2492
Copyright
Copyright by the authors.