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THE UNIVERSITY OF CALGARY Eric Snively A ... - Ohio University

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) Shaft and region of proximal articulations (distal to proximal). The figured<br />

MT III that was subject to measurement (Huene 1907-8: Figure 2.1 h) and the<br />

photographed specimen have a medial curvature. A more robust specimen lacks<br />

this curvature (Gresslyosau~s robustus in Heune l9Oï-û; referred to P.<br />

engelhardti by Galton 1 986).<br />

Two proximal features of the MT III of Plateosaurus differ greatly from the<br />

condition seen in theropods. The mesotarsal articular surface comes to a point<br />

anteriorly, making the proximal face of the metatarsal subtriangular in cross<br />

section. A keel extends distally from this apex, about 15-20% of the rnetatarsal's<br />

length along the anterior surface (Figure 2.1 h).<br />

These qualitative assessments delineate morphological variation along the<br />

longitudinal axis of the theropod MT III. The results and accompanying figures<br />

leave the impression of striking disparity in proximal robustness between the<br />

arctometatarsalian morphologies (typified by the tyrannosaurids, the<br />

ornithomirnid, Troodon, and Elmisaufus) and the other specimens. The<br />

quantitative results below provide an independent appraisal of the foregoing<br />

descriptive elucidation.<br />

QUANTITATIVE RESULTS<br />

Numerical results from PCA<br />

Table 2.4 displays the loading of each measurement along the first three<br />

principaI components, the percentages the measurements contribute to each<br />

component, and component correlations. The first three principal components<br />

account for 98.29% of total variance: PC1 explains û6.65%, PC2 10.61 4%, and

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