Boyer diss 2009 1046..

face ventrally. The centrum is rectangular with a distinct midline ventral ridge. Its
cranial facet faces cranially and is angled slightly ventrally. Within the vertebral canal,
the dorsal surface of the centrum is marked by two foramina. The transverse processes
are long and narrow, projecting inferolaterally.
Another cervical vertebra is represented by the centrum alone (Fig. 4.41D). It is
considered to be C4, even though it cannot be articulated with C3, due to the missing
caudal C3 epiphysis. There is slight mismatch between the caudal epiphysis of “C4” and
C6, which is taken as additional evidence that it is correctly identified as C4. The C4
centrum is even more “rectangular” than that of C3, because the dorsal and ventral
surfaces are parallel to one another, and there is no midline ridge on the ventral surface.
Like C3, there are two foramina on the dorsal surface. The cranial centrum facet faces
slightly ventrally, like that of C3. The caudal facet faces slightly dorsally; however it has
a dorsal lip, which makes the surface cylindrically concave.
The last preserved cervical vertebra is identified as C6, mainly due to the presence
of broken roots of hypertrophied anterior tubercles, as typically characterize this position
(Fig. 4.41E). The left half of the pedicle and lamina are also broken away, as are the tips
of the transverse processes. The prezygapophyses are oriented slightly more medially
than the dorsally facing facets of C3, while the postzygapophyseal facets are oriented
slightly more laterally than the ventrally facing facets of C3. The foramina transversaria
are preserved. The centrum is basically identical in shape and morphology to that of C4.
Comparison.—Again, a comparative context is needed to comment on
functionally salient features of the cervical vertebrae. C3, C4 and C6 in P. cookei have
morphology similar to that preserved in N. gidleyi and N. intermedius, although these
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