Boyer diss 2009 1046..

differences generated from information on skull length. The postcranium suggests that P.
cookei is at most five times the mass of the smallest plesiadapid N. intermedius, while the
skulls suggest that it was 10 or 16 times the mass. The contradiction between skull and
postcranial estimates most likely indicates that there is not an isometric relationship
between skull length and body mass among plesiadapids. Further, the negatively
allometric relationship of the Silcox et al. (in press) regression is an even less accurate
representation of the relationship between plesiadapid head length and body mass.
Instead, it seems that there is a positive allometric relationship between body mass and
head length among plesiadapids. That is, head length increases at a faster rate with
increasing body mass than predicted by isometry.
The fact that P. cookei and P. tricuspidens are estimated to have had a similar
body mass based on limb lengths and diameters is taken as further evidence that the
absolute difference in tooth size between these two taxa is due to different ecological
niches (see Chapter 3). A head that is relatively large compared to the body may promote
interspecific variance in tooth size that is not correlated to differences in body size.
SUMMARY
While the skeleton of P. cookei provides new insight into plesiadapiform
morphology and behavior, many of the observations presented here still have no
statistical basis and some of the comparative methods used to identify ambiguously
associated elements are speculative. Therefore, it is likely that some of the information
presented here is wrong, and that some of the conclusions based on it are misguided.
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