Boyer diss 2009 1046..

could be accomplished by rotating the transverse tarsal joints and metatarsals, but just
exactly how and how much these bones should be moved with respect to each other is
difficult to constrain. It is interesting to compare the posture of P. cookei depicted in
Figure 4.51 to the cineradiography-based drawing of hind foot reversal in Tupaia in
Jenkins (1974: p.102, fig. 6) because it shows the postures to be similar except for the
increased degree of abduction in the hind limb of P. cookei.
The major features differentiating P. cookei from other plesiadapids are its more
gracile limb bones, in some cases proportionally longer limb bones, and its proportionally
narrower intermediate phalanges (Boyer and Bloch, 2008). Additionally, P. cookei has
features of the ankle that appear to give it more mobility than the ankle of other
plesiadapids. The metacarpals of P. cookei and P. tricuspidens appear to be more robust
than those of Nannodectes, although not proportionally shorter compared to the
phalanges (see below). Finally, the vertebrae of P. cookei differ from those of
Nannodectes in having features that suggest the vertebral column was more rigid and
“stabile.” Overall, these unique features of P. cookei may correspond to a lifestyle that
was more committed to arboreal settings and possibly orthograde postures.
However, it has also been previously stated that P. cookei was not only an
arborealist but had morphology suggesting “suspensory tendencies” (Bloch and Boyer,
2007; Boyer and Bloch, 2008). These authors specifically mentioned features of the
scapula, humerus, intermediate phalanges and claws. The differences between the
scapulae of P. cookei and N. intermedius actually are consistent with a less mobile
shoulder in P. cookei and do not clearly support the case of a suspensory habitus in P.
cookei. While there are some differences between the humerus of P. cookei and those of
384