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dc.contributor.advisorChairperson, Graduate Committee: David Varricchioen
dc.contributor.authorFearon, Jamie Lynnen
dc.contributor.otherDavid J. Varricchio was a co-author of the article, 'Morphometric analysis of the forelimb and pectoral girdle of the Cretaceous ornithopod dinosaur Oryctodromeus cubicularis and implications for digging' submitted to the journal 'Journal of vertebrate paleontology' which is contained within this thesis.en
dc.contributor.otherDavid J. Varricchio was a co-author of the article, 'Reconstruction of the forelimb musculature of the Cretaceous ornithopod dinosaur Oryctodromeus cubicularis: implications for digging' submitted to the journal 'Journal of vertebrate paleontology' which is contained within this thesis.en
dc.date.accessioned2015-01-13T20:40:43Z
dc.date.available2015-01-13T20:40:43Z
dc.date.issued2013en
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/8756en
dc.description.abstractThe basal ornithopod dinosaur Oryctodromeus cubicularis was discovered within a burrow structure in the mid-Cretaceous Blackleaf Formation of western Montana. This, and features of the pelvis, skull, and forelimbs also seen in burrowing mammals led to the interpretation of Oryctodromeus as the first formally described burrowing dinosaur. This study further describes the forelimb specialization of Oryctodromeus and analyzes the validity of the interpretation of Oryctodromeus as adapted for digging using morphometric analyses and muscular reconstructions of the humerus, scapula, and coracoid. The morphometric analyses used two methods, including traditional morphometrics using principal component analysis of a series of element length measurements and geometric morphometrics using relative warp analysis of a series of landmarks superimposed on photographs of elements. Both methods reduce the number of variables to explain the greatest amount of variation between specimens. Results indicated that the humerus of Oryctodromeus is slightly more robust than other basal ornithopods, the coracoid exhibits no specialization for digging, and the scapula is strongly specialized, with a long narrow acromion and strongly expanded posteroventral margin of the scapular blade providing greater surface area for muscle attachment. Reconstruction of the forelimb musculature was generated by comparing both the presence or absence of muscles and the locations of attachment sites between birds and crocodilians, the extant phylogenetic bracket of dinosaur, and by examination of specimens of Oryctodromeus and other ornithopods for osteological correlates. Muscle groups used for burrowing in mammals include the deltoideus scapularis, latissimus dorsi, triceps longus, and teres major. The first three are present in Oryctodromeus, but the presence of the teres major is equivocal. The strongly expanded posteroventral scapula indicates an increased surface area for the origin of the deltoideus scapularis and possibly teres major. This expanded area would be advantageous for burrowing. The origin of the triceps longus near the glenoid of the scapula would not provide strong extension of the antebrachium, a motion important in scratch-digging. The osteology and musculature both provide evidence of slight adaptation for scratch-digging in Oryctodromeus. As many vertebrates burrow without morphological specializations, the presence of these features sufficiently supports adaptation for burrowing in Oryctodromeus.en
dc.language.isoenen
dc.publisherMontana State University - Bozeman, College of Letters & Scienceen
dc.subject.lcshOrnithischiaen
dc.subject.lcshForelimben
dc.subject.lcshBurrowing animalsen
dc.subject.lcshFossilsen
dc.subject.lcshAnatomy, Comparativeen
dc.titleScratch-digging in the Cretaceous basal ornithopod dinosaur Oryctodromeus cubicularis : evidence from morphometric analyses and reconstruction of the forelimb musculatureen
dc.typeThesisen
dc.rights.holderCopyright 2013 by Jamie Lynn Fearonen
thesis.catalog.ckey2666221en
thesis.degree.committeemembersMembers, Graduate Committee: Steve Cherry; John R. Horneren
thesis.degree.departmentEarth Sciences.en
thesis.degree.genreThesisen
thesis.degree.nameMSen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage172en
mus.data.thumbpage128en


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