Boyer diss 2009 1046..

form. The bulla measures 11.23 mm in anteroposterior length. There is no obvious suture
with the ectotympanic (Figs. 2.10-12).
Ectotympanic.— The left ectoympanic is missing most of the eam. The crista
tympanica and its concentric, inward projection are visible (Figs. 2.11, 12: 44). On the
right side, some of the eam is preserved (Fig. 2.9). It was 4.07 mm in mediolateral
projection. Its anteroposterior width is not preserved well enough to allow measurement;
however, it can at least be stated that the eam was not tubular. The crista tympanica is not
as well preserved on this side (Fig. 2.9: 44), but more of it is visible. The connection
between the crista tympanica and the bulla is solid and marked by subtly raised ridges
(Fig. 2.9: 45), not prominent bony struts as in P. tricuspidens. The diameter of the crista
tympanica is 5.3 mm (although it may be slightly distorted) and gives an indication of the
tympanic membrane diameter. As with other plesiadapids there is no telling how much of
the eam and bulla were comprised of ectotympanic.
Occipital.— The occipitals are fairly well preserved (Figs. 2.10, 11, 13). The
basioccipital is a narrow element 7.22 mm in anteroposterior length and 2.21 mm in
width at the spheno-occipital synchondrosis (Figs. 2.10, 11). At the anteroposterior
midpoint the width is 2.04 mm. The width of the posterior margin cannot be measured
reliably due to breakage. There is only faint development of a sagittally positioned
longitudinal ridge on the element (Figs. 2.10, 11, 13: 46). The lateral margins project
ventrally and would have braced the edge of the bulla in the pristine specimen (Figs.
2.11, 13: 47).
The preserved parts of the exoccipitals include the right occipital condyle (Figs.
2.10, 11, 13: 48), foramen magnum diameter (Fig. 2.13: 49), and jugular process (Fig.
52