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

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positively with relative metatarsal gracility, while proximal width decreases with<br />

gracility. However, a high positive loading for HGlNGL may reflect the relatively<br />

high values for this measurement in the large tyrannosaurid specimens (see<br />

Discussion), and therefore may be correlated more with overall metatarsal length<br />

than with proximal narrowing.<br />

Grouping of speàmem by PCA<br />

Table 2.5 gives statistics for al1 specimens measured for PCA, including the<br />

total variance for each specimen, the amount of each specimen's variance<br />

explained by each PC (Varcamp), and the distance of the specimen from the<br />

origin of al1 PC axes. The last quantity gives the degree of deviation from a<br />

hypothetical average morphology in size and shape as deterrnined by the<br />

constituency of the entire data base. The value of distance from the origin is<br />

simply the square root of the variance, and is the number of standard deviation<br />

units (SD) a specimen plots away from the origin.<br />

The distribution of standard deviations (Distance: Table 2.5) facilitates the<br />

general identification of unusual and typical morphologies. Because PC1 , a size<br />

related component, explains 86.65% of total variance, distance from the origin in<br />

SD primarily shows deviations in overail size from the average of the sample. At<br />

0.15 SD, the Elaphrosaurus MT III is closest to the average in linear dimensions.<br />

By far the most aberrant are Omzholestes and the smaller lngenia specimen, at<br />

distances of 1.474 and 1.480 SD, respectively. These are the smallest<br />

specimens in overall length. At the other extreme, Allosaurus (Saurophaganax)<br />

maximus (1 .O8 SD) and the larger Tjmnnosaurus rex specimen (1 -04 SD) have

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