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Dissertation
The morphology, histology, and molecular preservation of an exceptionally complete titanosaur from southernmost Patagonia
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2013
DOI:
https://doi.org/10.17918/etd-6996
Abstract
In this dissertation, I characterize the gross morphological, histological, and molecular preservation of a new titanosaur, MPM-PV 1156, a massive (~62.5 metric tons) sauropod from the Cerro Fortaleza Formation (Campanian-Maastrichtian) of southernmost Patagonia, Argentina. This specimen possesses an exceptionally complete postcranial skeleton (~70%), and presents a unique opportunity to investigate a titanosaurian dinosaur at multiple levels of its preservation. Here, I describe the single preserved cervical vertebra of MPM-PV 1156 and determine its serial position by comparing it with cervical vertebrae of titanosaurian specimens with nearly complete cervical series. Based on its neural spine morphology and relative centrum length, the cervical of MPM-PV 1156 is likely a mid-posterior in the range of 9-11. Further, it is distinguished from the mid-posterior cervical of Puertasaurus, another titanosaur from the Cerro Fortaleza Formation, by morphological differences in their neural spines and connecting laminae. Histological examination of the humerus and femur of MPM-PV 1156 reveals rapidly growing fibrolamellar bone at their periosteal surfaces, and a lack of features that mark cessation of growth. These characteristics indicate that despite its enormous size, MPM-PV 1156 was actively growing at its time of death. A shorter femur from a second titanosaur individual (MPM-PV 3546), recovered at the same locality as MPM-PV 1156, was also examined. This deformed femur appears osteologically more mature than MPM-PV 1156, suggesting that its diminished size does not reflect a younger age, but other possible factors, such as diagenesis, pathology, and sexual dimorphism. Additionally, I present four independent lines of evidence to support the preservation of endogenous soft-tissues in MPM-PV 1156. The presence of these tissues, including vessels, osteocytes, and bone matrix proteins (collagen I and fibronectin), is evaluated using microscopy, in-situ localization (immunofluorescence), immunoreactivity to chemical extracts (enzyme-linked immunosorbent assay), and silver-staining of chemical extracts. All results support the conclusion that biomolecules are preserved in the fossils of MPM-PV 1156, and fail to show evidence of similar molecular content in the entombing sediment or chemical reagents used. These results provide the first direct evidence of collagen I in a sauropod dinosaur, and the first report of fibronectin from pre-Quaternary fossils.
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Details
- Title
- The morphology, histology, and molecular preservation of an exceptionally complete titanosaur from southernmost Patagonia
- Creators
- Elena Ann Rita Schroeter - DU
- Contributors
- Kenneth Lacovara (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xxviii, 243 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biology; College of Arts and Sciences; Drexel University
- Other Identifier
- 6996; 991014632945304721