Boyer diss 2009 1046..

Distal phalanges
Description.—There are ten distal phalanges preserved, only three of which are
virtually complete (Fig. 4.22, Table 4.15). These elements are all quite similar to each
other. There is no morphological basis to sort manual and pedal claws. There are,
however, two phalanges in the sample (Fig. 4.22A, D) that appear similar to one another
and different from the others. They have a mediolaterally wider flexor tubercle that also
has two processes that project proximally from the lateral aspects of its proximal margin.
If there is any significance to this distinctive morphology, it may be that these two
phalanges represent first digits.
The distal phalanges can be described as relatively large, “hook-like” claws with
narrow shafts and pronounced flexor tubercles. More specifically, the proximal articular
surface is much taller dorsoventrally than it is mediolaterally wide. It is marked by a
central ridge, which meets the central grooves of the corresponding distal facet on the
intermediate phalanges. Dorsal to the proximal articular surface is a vertically expanded
area for insertion of the extensor tendon (the extensor tubercle). Ventral to the proximal
articular surface is another larger vertically expanded area, possibly for contact with a
distal sesamoid. Distal to this, on the ventral surface of the claw, are two nutrient
foramina – spaced side by side with a thin rod of bone separating them. Distal to these
foramina is the flexor tubercle. The flexor tubercle is usually slightly longer
proximodistally than mediolaterally wide. Its mediolateral width is typically greater than
that of the claw shaft to which it attaches. The ventral surface of the flexor tubercle is
typically separated proximodistally into three regions. The most proximal part is flat to
slightly convex, is continuous with the rod-like bony process separating the nutrient
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