Boyer diss 2009 1046..

identifiable. No ethmoid foramina could be identified. At the parietal’s most anterior
point of contact with the frontal, it reaches a few millimeters beyond the apex of the
converging temporal crests, to the point of maximum mediolateral constriction of the
orbitotemporal region (Fig. 3.1, 4: 17). This suture is difficult to see with the naked eye
or light microscopy; however, HRxCT imagery reveals its position and form more
distinctly. The parietal onlapped the frontal (Fig. 3.7: 18). Thus, although much of the
neurocranium has an “outer shell” of parietal, the frontal extends quite far posteriorly.
Most likely, the frontal forms at least the anterior part of the endocranial surface, the
topology of which reflects that of the brain, mainly the olfactory bulbs (Fig. 3.5: 19). In
fact, the posterior part of the frontal has its endocranial surface and the endocranial
expression of its suture with the parietal exposed (Fig. 3.5: 20). This region is described
by Gingerich and Gunnell (2005).
Palatine.— The palatal processes of the palatines are visible and well preserved
(Fig. 3.5). The base of the left pterygoid process is preserved (Fig. 3.5: 21). More of the
posterior parts also may be present, but shifted dorsally and posteriorly into the
neurocranium (Fig. 3.5). On the palate, the palatines terminate at the choanae in a
swollen rim of bone, also referred to as a postpalatine torus (Fig. 3.5: 22). The outer
margin of the torus reaches the lateral margin of the pterygoid processes. Furthermore,
the outer margin of the torus is sharply angled, with the anterior part of it following a
straight, transversely-running course, and the lateral parts following a straight,
anteroposteriorly-running course. Prior to shifting of the contralateral palatines the inner
margin of the horizontal process of the palatine, which forms the direct boundary to the
choanae, would have been biconcave with a postpalatine spine present (Fig. 3.5: 23). This
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