Boyer diss 2009 1046..

have stouter shaft diameters for their length, and to have absolutely and proportionally
shallower dorsoventral dimensions of the proximal and distal ends. Natural logarithm
shape ratios constructed to quantify these differences show that among the P. cookei
sample, as well as among other plesiadapids, the manual proximal phalanges are probably
more robust (have a greater SSV: Table 4.13). However, the dorsoventral dimensions of
the proximal and distal ends to not appear to consistently differentiate proximal
phalanges into manual and pedal groups (BSV and HSV: Table 4.13).
In general all proximal phalanges have a proximal articular surface that is
spherically concave. Relative to the shaft, the proximal articular surface faces proximally
and slightly dorsally. A pair of tubercles laterally flanks the proximal articular surface
and extends proximoventrally. These tubercles are usually asymmetrical with one being
larger, blunter, and extending farther proximally than the other. Distal to the proximal
end, the shaft narrows mediolaterally to near its midpoint, before widening slightly just
proximal to the distal articular surface. The dorsoventral dimensions of the shaft tend to
decrease continuously from the proximal to distal end. Oftentimes the shaft curves away
from the side with the larger proximal tubercle. The ventral surface of the shaft is usually
marked by prominent flexor sheath ridges. Although these ridges are impressive in
covering almost the entire length of the shaft, they are subtle in their ventral projection.
Their presence is more distinctly highlighted by the groove formed where they meet the
ventral surface of the shaft (Figs. 4.19, 20). The distal articular surface is distinctive in
the presence of two longitudinal grooves separating three trochleae, as can be seen in
ventral and distal views of these bones. The lateral trochleae are mediolaterally narrower
than the median one. They also tend to have a larger radius of curvature. One of the
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