Boyer diss 2009 1046..

distinct, convex distal radial facet reinforces the inference that there was substantial axial
mobility in the radius with respect to the ulna. Its location on the dorsal aspect of the ulna
is consistent with morphology of the radius, suggesting that the wrist was maintained in a
semi-supinated orientation most of the time.
Comparison.—In general, the ulna of P. cookei does not differ appreciably from
those of other plesiadapids. None of the shape indices in Table 4.6A reveal any
quantified differences. Qualitatively comparing more subtle aspects of the morphology,
it can be stated that the ulna of P. cookei seems to be unique in the shallowness of the
longitudinal groove marking the lateral side of its shaft for origination of extensor
musculature. The ulna of P. cookei also appears more gracile than those of other
plesiadapids; however, as mentioned, this is not borne out by any measurements (e.g.,
Table 4.5A: NSV and SSV).
Scaphoid
Description.—The right scaphoid is preserved (Table 4.6; Fig. 4.7A). It was
originally identified by comparisons to the scaphoid of N. intermedius USNM 442229
(Beard, 1993a) and a scaphoid dentally associated to the paromomyid Acidomomys
hebeticus (Boyer and Bloch, 2008). Aside from being “boat-shaped,” as the etymology
of the bone’s name suggests, with a convex proximal articular surface forming the “hull
of the boat” and the concave distal articular surface forming the “boat’s interior,” the
scaphoid of P. cookei could also be described as “barbell-shaped” because the ventral
tubercle is quite large and distinct from the articular surface for the radius. On the
proximal surface, the radius facet is triangular to pyriform in outline (Figs. 4.7A, 4.8: 5),
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