Pneumatic postcranial bones in dinosaurs and other archosaurs

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dc.contributor.advisorHall, Russell L.
dc.contributor.authorBritt, Brooks B.
dc.date.accessioned2005-08-05T16:38:01Z
dc.date.available2005-08-05T16:38:01Z
dc.date.issued1993
dc.descriptionBibliography: p. 290-317en
dc.description.abstractAmong amniotes, pneumatic postcranial bones are shared by Aves, Theropoda, Sauropoda, and Pterosauria. Comparison of pneumatic characters in the vertebrae of birds and non-avian dinosaurs demonstrates that the Theropoda and the Sauropoda had pneumatic vertebrae and ribs. Pneumatic bones of the extinct taxa were invaded by diverticula of an air sac system homologous with that of birds. The nature and extent of pneumatic features in the vertebrae were studied with the aid of cut sections, standard x-rays, and computed tomography. Two types of dinosaurian pneumatic vertebrae are recognized based on internal structure: 1) simple (camerate), with relatively large, open chambers or fossae, as in Syntarsus, Torvosaurus, Saurornitholestes, and Barapasaurus; and 2) complex (camellate), with supernumerary, interconnected chambers as in Tyrannosauridae, Ornithomimidae, Aves, and Pterosauria. Among the Theropoda complex vertebrae are restricted almost exclusively to Tetanurae, suggesting that this is an apomorphic character state for that taxon. Pterosaurs, sauropods, and theropods share with birds dorsoventrally widelyseparated articular facets on the ribs. Pneumatization significantly reduced the mass of dinosaur vertebrae. The location of diverticula tracks and foramina in some non-avian tetanuran theropods suggests that the air-sac system played a role in thermoregulation, as in extant birds. Pneumatic characters are of major taxonomic and phyletic significance because they can be used to test phyletic hypotheses based on other character suites, as well as to diagnose taxa. It is demonstrated that segnosaur vertebrae were pneumatic and of the complex type. These characters, along with non-pneumatic characters, indicate the enigmatic segnosaurs are tetanuran theropods. The distribution of pneumatic characters suggests that Pterosauria, Theropoda, and Sauropoda share a close common ancestry. Pneumatic postcranial bones indistinguishable from those of theropods are present in Archaeopteryx. Therefore, postcranial pneumaticity in birds is not an adaptation but an exaptation to flight. Pneumatic para-axial postcranial bones are found only in pterosaurs and birds, indicating that they are an adaptation to flight.en
dc.format.extentxvii, 383 leaves : ill. ; 30 cm.en
dc.identifier.citationBritt, B. B. (1993). Pneumatic postcranial bones in dinosaurs and other archosaurs (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/12190en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/12190
dc.identifier.isbn0315831057en
dc.identifier.lccQE 862 D5 B74 1993aen
dc.identifier.urihttp://hdl.handle.net/1880/30913
dc.language.isoeng
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
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.
dc.subject.lccQE 862 D5 B74 1993aen
dc.subject.lcshDinosaurs
dc.subject.lcshBones - Analysis
dc.titlePneumatic postcranial bones in dinosaurs and other archosaurs
dc.typedoctoral thesis
thesis.degree.disciplineGeology and Geophysics
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
ucalgary.thesis.accessionTheses Collection 58.002:Box 859 520541929
ucalgary.thesis.notesoffsiteen
ucalgary.thesis.uarcreleaseyen
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