Boyer diss 2009 1046..

zero or less were excluded from geometric mean calculations (e.g., the distance that the
greater trochanter of the femur projects proximal to the femoral head could easily be
positive, zero or negative in a taxon of any absolute size). Particular variable sets used to
create geometric means are cited in relevant table legends below. The resulting
geometric mean ratios were then natural-log transformed. Whether it is necessary to use
logarithms of ratios is debated (e.g., Jungers et al., 1995). I chose to do so here based on
the fact that it frequently improves normality of distributions of ratios (Sokal and Rohlf,
1997). Furthermore my own experimentation with different data formats lead me to use
logs rather than raw ratios. For instance, a version of the analysis of humeral variables
performed on un-logged ratios captured less variance, and captured it less evenly in the
first two coordinates, than the logged version of the same data (see additional discussion
in Chapter 5).
Body mass estimation.—Body mass is estimated for P. cookei and other
plesiadapids using six limb bone lengths and six diameters. Two different sets of
regressions are used: Gingerich (1990) generated regressions from data of Alexander et
al. (1979). This dataset samples a phylogenetically diverse array from shrews to
elephants. An unpublished dataset of primates from the UMMZ collection is used to
generate a parallel set of regressions. The results of these two sets of regressions are
presented and compared.
Intrinsic hand proportions.—A reconsideration of digit proportions of P. cookei
using methods and the comparative data set of Kirk et al. (2008) is undertaken.
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