The parietal eye (PE) in modern squamates (Reptilia) plays a major role in regulating body temperature, maintaining circadian rhythms, and orientation via the solar axis. This study is the first to determine the role, if any, of the PE in an extinct group of lizards. We analyzed variation in relative size of the parietal foramen (PF) of five mosasaur genera to explore the relationship between PF size and paleolatitudinal distribution. We also surveyed the same specimens for the presence of avascular necrosis—a result of deep- diving behavior—in the vertebrae. Plioplatecarpus had the largest PF followed by Platecarpus, Tylosaurus, Mosasaurus, and Clidastes. A weak relationship exists between paleolatitudinal distribution and PF size among genera, as Plioplatecarpus had the highest paleolatitudinal distribution (~78°N) and the largest PF among genera. Clidastes, Mosasaurus, Platecarpus, and Tylosaurus, however, shared a similar northern paleolatitude (~55°N) extent despite Platecarpus having a statistically larger PF than the other three genera (p<0.001 in Fisher’s LSD test). Mosasaurus, Plioplatecarpus, and Tylosaurus also shared a similar southern paleolatitude (~64°S) despite Plioplatecarpus having a larger PF. There is no correlation between PF size and paleolatitudinal distribution for specimens within genera. We found no relationship between PF size and presence of avascular necrosis. Tylosaurus and Mosasaurus, which exhibited avascular necrosis, had a similar PF size to Clidastes, which did not avascular necrosis. The PE of mosasaurs may have functioned primarily for navigation and orientation related to migration; however, this possibility requires further study of modern PE-bearing organisms and its function.
|Commitee:||Brown, Rafe, Roberts, Jennifer|
|School:||University of Kansas|
|School Location:||United States -- Kansas|
|Source:||MAI 56/01M(E), Masters Abstracts International|
|Keywords:||Mosasaur, Parietal eye, Parietal foramen, Platecarpus, Plioplatecarpus|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be