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Title: The phylogeny and early evolution of the ornithischian dinosaurs
Author: Butler, R. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
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The Elliot Formation of South Africa and Lesotho contains one of the most important but relatively understudied, early ornithischian faunas; here a review is presented of its known ‘fabrosaurid’ (non-heterodontosaurid) specimens. The first ornithischian collected from the Lower Elliot Formation (Late Triassic) is described, representing a new taxon of basal ornithischian. Within the Upper Elliot Formation (Early Jurassic), ‘Fabrosaurus australis’ is considered a nomen dubium, a new diagnosis of Lesothosaurus diagnosticus is presented, and a new taxon, Stormbergia dangershoeki gen. et sp. nov., is described. A comprehensive new cladistic analysis tests global ornithischian phylogeny. Results support the generally understood framework of ornithischian interrelationships; however, support is weak for many major clades, and the positions of certain taxa differ significantly from previous analyses. The enigmatic clade Heterodontosauridae may represent some of the most basal known ornithischians. Strong evidence supports hysilophodontid paraphyly, with some Middle Jurassic taxa (Agilisaurus, Hexinlusaurus) cladding as sister taxa to Cerapoda (Marginocephalia + Ornithopoda). Biogeographical analyses support hypotheses of vicariance related to the Late Jurassic geographical isolation of Asia. Synthesis of anatomical, taxonomic, phylogenetic, and biogeographical data allows the development of a broad overview of early ornithischain evolution. Triassic ornithischians were scarce and geographically limited. Ornithischians underwent a significant increase in diversity, abundance, and geographical distribution across the Triassic-Jurassic boundary, perhaps coincident with the origin of the clade Genasauria.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available