Boyer diss 2009 1046..

Its anteroposterior length is 4.49 mm, while its mediolateral width is 4.11 mm. Due to
broken anterior and medial margins and a missing entoglenoid process, these values are
likely to underestimate the dimensions of the pristine element. The postglenoid process
projects straight ventrally by 1.43 mm. On the left side, some of the zygomatic process of
the squamosal is preserved (Fig. 2.8), but not enough to warrant description.
Petrosal.— Both petrosals are preserved, including regions of pars cochlearis and
canalicularis (Figs. 2.9-13). Remains of both ectotympanics and a substantial portion of
the left auditory bulla also exist. The maximum diameter of the aperture for the fenestra
vestibuli is 1.16-1.19 mm (left-right). The left spiral cochlea measures 14.5 mm in length
(Fig. 2.9H) and completes 2.5 turns. The width of the pars cochlearis is 3.6-3.8 mm,
while its dorsoventral depth as measured from the endocranial surface is 3.5-3.6 mm.
The promontorium has only two visible grooves on its surface (Figs. 2.9-11). The
identification of some of these requires consideration of how they relate to the preserved
bony septa that buttress the promonotory. Four bony septa are preserved. The left
promontorium visibly preserves the posterior septum (Figs. 2.10, 11) and the s1 (Fig.
2.11A-C, C’, E). HRxCT data shows that it additionally preserves the s2, and cochlear
canaliculus, but no s3, arising from the medial tympanic process (Fig. 2.11E). This
medial process appears to have a smooth, edge. It projects medially from the
promontorium an average distance of 1.2 mm. The right promontorium preserves the
cochlear canaliculus, but is broken on the medial side more anteriorly (Fig. 2.9).
The g1 groove is present on the ventrolateral aspect of the promontorium. It
actually grooves the ventral part of the posterior septum anteriorly; however, more
posteriorly, it diverges to the lateral side of the posterior septum (Figs. 2.9-11). The g1
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