Juvenile specimens of Prosaurolophus maximus (Hadrosauridae, Saurolophinae) from the marine Bearpaw Formation (upper Campanian, Upper Cretaceous) of southern Alberta, Canada reveal ontogenetic change in crest morphology

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dc.contributor.advisorZelenitsky, Darla K.
dc.contributor.advisorTherrien, François
dc.contributor.authorDrysdale, Eamon Thomas
dc.contributor.committeememberTheodor, Jessica M.
dc.contributor.committeememberDutchak, Alexander
dc.date2019-06
dc.date.accessioned2019-01-29T22:36:36Z
dc.date.available2019-01-29T22:36:36Z
dc.date.issued2019-01-25
dc.description.abstractThree juvenile specimens of Prosaurolophus maximus, represented by both articulated and disarticulated skeletal material, are the smallest known individuals for the taxon. Their cranial anatomy indicates that the diagnostic characters of P. maximus are ontogenetically variable. In the smallest specimen, the crest and deeply-excavated fossa at the caudal margin of the circumnarial depression are poorly-developed or absent. In the larger specimens, the crest approaches the morphology observed in subadult and adult specimens but lacks the robusticity and deep excavation of the circumnarial depression typical of P. maximus. In contrast, the shape of the caudal end of the circumnarial depression is ontogenetically consistent, potentially making it a reliable character for taxonomic identification. Histological sections from the three juvenile specimens and one large individual indicate that the minimum biological age of the known specimens of P. maximus ranges from two to five years. Given that the large P. maximus individual has yet to reach skeletal maturity, the species may reach a maximum body size larger than represented by currently known specimens, perhaps with a skull length approaching the size of Saurolophus angustirostris. The lack of positive allometric growth associated with the P. maximus crest, which undergoes isometric growth from age three onward, differs from that observed in lambeosaurine hadrosaurs suggesting that the crest may not have been the result of sexual selection. However, positive allometric growth of the circumnarial region and the rugosity of the bony crest suggests that soft tissue structures associated with the narial-crest region, rather than the bony crest itself, may have been selected for sexual display in P. maximus. The juvenile specimens were recovered from sediments of the Bearpaw Formation deposited during the Baculites compressus ammonite zone and magnetochrons 33n.3n to 33n.2n. They are stratigraphically younger than P. maximus specimens from the Dinosaur Park Formation, and contemporaneous to 100,000 years younger than specimens from the Two Medicine Formation, extending the taxon’s temporal range. The occurrence of P. maximus in the marine deposits of the Bearpaw Formation and well-drained upland terrestrial deposits of both the Dinosaur Park and Two Medicine formations suggests that this taxon inhabited various palaeoenvironments.en_US
dc.identifier.citationDrysdale, E. T. (2019). Juvenile specimens of Prosaurolophus maximus (Hadrosauridae, Saurolophinae) from the marine Bearpaw Formation (upper Campanian, Upper Cretaceous) of southern Alberta, Canada reveal ontogenetic change in crest morphology (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/36129
dc.identifier.urihttp://hdl.handle.net/1880/109872
dc.language.isoenen_US
dc.publisher.facultyScienceen_US
dc.publisher.institutionUniversity of Calgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.subjectDinosauren_US
dc.subjectPalaeontologyen_US
dc.subjectOntogenyen_US
dc.subjectHadrosauren_US
dc.subjectProsaurolophusen_US
dc.subjectJuvenileen_US
dc.subjectBearpawen_US
dc.subjectHistologyen_US
dc.subjectMorphometricsen_US
dc.subject.classificationAnatomyen_US
dc.subject.classificationGeologyen_US
dc.subject.classificationPaleoecologyen_US
dc.subject.classificationPaleontologyen_US
dc.subject.classificationPaleozoologyen_US
dc.titleJuvenile specimens of Prosaurolophus maximus (Hadrosauridae, Saurolophinae) from the marine Bearpaw Formation (upper Campanian, Upper Cretaceous) of southern Alberta, Canada reveal ontogenetic change in crest morphologyen_US
dc.typemaster thesisen_US
thesis.degree.disciplineGeoscienceen_US
thesis.degree.grantorUniversity of Calgaryen_US
thesis.degree.nameMaster of Science (MSc)en_US
ucalgary.item.requestcopytrue
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