Boyer diss 2009 1046..

etween N. gidleyi and other plesiadapids — a convex, rather than concave lateral
condyle, as seen in tree squirrels and treeshrews — is also consistent with agile
pronograde locomotion.
Fibula
Description.—The fibula is known from fewer plesiadapid specimens even than
the tibia. However, both right and left fragmentary fibulae are preserved with UM 87990
(Figs. 4.27, 28; Table 4.19). The right side has an undistorted complete diaphysis, the left
is broken, and shifted (this seems to be postmortem breakage). The epiphyses are missing
from both elements. The proximal end of the shaft, where the epiphysis would have
sutured, is expanded anteromedially to posterolaterally, but is narrow in the perpendicular
direction. Thus the proximal shaft can be described as “blade-like.” Approximately 2
mm distal to the proximal end, the shaft depth narrows to about two-thirds its proximal
end depth. Farther distally, the shaft continues to narrow gradually until just prior to
reaching the distal end, where it flares out in all directions and develops an
anteromedially oriented rugosity, which would have contacted the fibular notch of the
tibia, just posterior to the tibia’s crest for the anterior tibiofibular ligament. The
anteromedial “edge” of the “blade” of the fibula’s proximal end is concave, while the
posterior posterolateral margin is convex. The proximal end of the anterolateral surface
has a proximodistally oriented crest toward the anterior margin that separates this bone
into a smaller, more anteriorly-facing surface and a posterior more laterally-facing
surface. The more anterior surface is that typically referred to as the anterior surface with
medial and lateral lips (Stern, 1988), while the larger, more posterior surface is equivalent
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