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dc.contributor.advisorChairperson, Graduate Committee: John R. Horneren
dc.contributor.authorBallard, HollyNoelle Woodwarden
dc.contributor.otherJohn R. Horner and James O. Farlow were co-authors of the article, 'Quantification of intraskeletal histovariability in Alligator mississippiensis with implications for non-avian dinosaur paleohistology' which is contained within this thesis.en
dc.contributor.otherJohn R. Horner and James O. Farlow were co-authors of the article, 'Osteohistological evidence for determinate growth in the American alligator' in the journal 'Journal of herpetology' which is contained within this thesis.en
dc.contributor.otherThomas H. Rich, Anusuya Chinsamy and Patricia Vickers-Rich were co-authors of the article, 'Growth dynamics of Australia's polar dinosaurs' in the journal 'Public library of science ONE' which is contained within this thesis.en
dc.contributor.otherJohn R. Horner and Elizabeth A. Freedman were co-authors of the article, 'A population histovariability analysis of the hadrosaurid dinosaur Maiasaura peeblesorum' which is contained within this thesis.en
dc.description.abstractThe microstructure of bone can be used to infer growth rate, physiology, and age of a taxon. Because of this, bone histology is frequently employed in studies of non-avian dinosaurs to better understand how they grew. Unfortunately, the potential for individual skeletal variability is rarely accounted for in extant studies, making interpreting the growth histories of dinosaurs somewhat ambiguous. This dissertation addresses the question of individual variability in the bone microstructure of an extant dinosaur relative, the American alligator, thus aiding in establishing a baseline from which to draw conclusions about the growth of dinosaurs. Appendicular elements of thirty three alligators demonstrate growth rate variability within elements of the same individual, and also across individuals. Regardless, no element skipped yearly growth mark deposition. Additionally, some alligators possessed an external fundamental system (EFS), revealing that skeletal maturity was achieved. This suggests that dinosaurs likely also had determinate growth. Next, the results of the alligator studies were used to reassess the interpretations of previous dinosaur paleohistology studies. Reanalysis of polar dinosaur histology using seventeen samples falsifies the hypothesis that growth marks are related to hibernation, demonstrating the danger of drawing conclusions about behavior from only two samples. The histology of Raptorex was similarly reassessed, with the microstructure here interpreted as that of an immature individual rather than a subadult or early adult. Finally, a new histological study on the dinosaur Maiasaura demonstrates the growth rate variability within a taxon that often goes unaccounted for in smaller sample sets. With forty eight tibia specimens, this represents the largest single-element dinosaur histology study to date. In general, the first growth mark, indicating yearlings, appears in animals that would have been between 2.5 m and 3.5 m in body length. The largest individuals have not only LAGs but also EFS. Growth appears to plateau between nine and ten years, supporting the findings of the original Maiasaura growth study. However, this study also shows there is a considerable degree of individual variation in growth rates, and cautions against constructing generalized growth curves using only a handful of specimens.en
dc.publisherMontana State University - Bozeman, College of Letters & Scienceen
dc.subject.lcshAmerican alligatoren
dc.titleComparative population histovariability within the Archosauriaen
dc.rights.holderCopyright 2012 by HollyNoelle Woodward Ballarden
thesis.catalog.ckey2592017en, Graduate Committee: David Varricchio, Susan Gibson, James Farlowen Sciences.en

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