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Functional morphology and phylogeny of Keichousaurus hui (Sauropterygia, Reptilia

Keichousaurus hui Young, 1958, from the Middle Triassic of Guizhou, China is a small sauropterygian reptile. It has short snout and elongated temporal openings resembling the European pachypleurosaurid Dactylosaurus. Unlike all the other sauropterygians, the parietal opening is anteriorly positioned. The neck is long and flexible. The body is rigid and the bones are pachyostotic. It has two or three sacral vertebrae. The most striking feature of Keichousaurus is its broad ulna. The entire forelimb has the outline of a paddle or an oar, and may have functioned like one. There is noticeable sexual dimorphism, as is the case for Alpine pachypleurosaurids. The growth of the humerus is highly positive allometric, indicating an important role of the forelimb in locomotion. The horizontal orientation of the pectoral girdle indicate that Keichousaurus, as well as other pachypleurosaurids, was not a subaquatic flyer. Instead, a drag-based regime was followed in locomotion. The symmetrical rowing of the forelimbs precludes lateral undulatory movement of the body. However, vertical undulation is theoretically possible. The reassessment of the phylogenetic position of Keichousaurus hui confirmed that it is a member of the monophyletic group Pachypleurosauroidea.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28485
Date January 1994
CreatorsLin, Kebang
ContributorsCarroll, Robert L. (advisor)
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageDoctor of Philosophy (Department of Biology.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 001432947, proquestno: NN00110, Theses scanned by UMI/ProQuest.

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