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

1995), can informatively map specimens onto graphs of two or three pertinent
variables. Principal Cornponents Analysis has two major advantages over these
approaches. First, because PCA consolidates multiple variables, it distills trends
and correlations in voluminous data more expeditiously than juxtapositions of
onIy h o or three measurements (Weishampel and Chapman 1 990). Second,
?CA atso calculates the relative contribution of specifk measurements ta overall
variation. Specirnens are plotted ont0 graphs of the most important constituents
of variation, which can be interpreted as important differences in shape or sire.
This statistical segregation of metatarsal morphologies, complemented by
thorough description, potentialiy suggests analogous andior homoIogous pedal
biornechanics within various groups. If discrete morphologies can be classified
statistically and qualitatively, the separation fosters the development of
biomechantcal, functional, and phylogenetic hypotheses. The work in mis chapter
therefore integrates descriptive and mathematical approaches in order to derive
such hypotheses.
General approach and hypotheses
Qualitative methods elucidate subtleties of morphology apparent in theropod
third metatarsals, and PCA is then used to circumscribe morphologies on the
basis of anterior silhouette. Specifically, the goals and approaches are as foltows:
1) Results from qualitative description of specimens are applied to the
following hypothesis:
Ha: The tyrannosaurid MT III is qualitatively diierentiable from sirnilar forms in
ways not predictable h m simple allometry.