Boyer diss 2009 1046..

autapomorphy, because it appears that the lunate ossification center in Cynocephalus
intervenes between the triquetrum and scaphoid before fusing to the scaphoid. From a
phenetic perspective, the fact that plesiadapids have humeri that are morphologically
more similar to those of primates than to those of other euarchontans could reflect a
special relationship of plesiadapids (and other plesiadapiforms) to euprimates. However,
this signal is not paralleled by similar analyses of the morphology of the astragalus,
calcaneum, vertebrae, or body segments.
Functional significance.—The opportunity to consider the functional significance
of mobility at several joints of the limbs at a time is a major benefit provided by such a
complete skeleton of a single individual. Analyses presented in the Results section reveal
that P. cookei probably utilized postures in which the arm was typically extended or
flexed in the sagittal plane to some degree, but not substantially abducted or laterally
rotated (i.e., the distal end of the humerus pointed caudally or ventrally, but not
substantially laterally). As discerned in previous studies of P. tricuspidens (Szalay et al.,
1975), it seems that the elbow was typically flexed from a fully extended posture by
around 90º or more. The forearm would have been abducted by ~30º, relative to the
anteroposterior axis of the humerus. The manus was typically partly supinated and
slightly dorsiflexed, although it had the capacity for a large range of dorsiflexion. The
mechanical capacity for such a large range of dorsiflexion of the hand (and digits) is most
likely important for pronograde quadrupedalism, and possibly descents of large diameter
vertical substrates (Jenkins, 1974).
A typical hind limb posture would have been characterized by a femur that was
abducted, flexed, and laterally rotated relative to the innominate. The knee would have
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