Boyer diss 2009 1046..

Figure 2.39. UM 108207 Acidomomys hebeticus: Left promontorial fragment of petrosal
HRxCT surface reconstructions and individual slices (64, 175, and 274 – slice numbers
increase anteriorly). Medial is to left in all images. This individual is a juvenile with very
porous bone, unshed deciduous teeth and unerupted adult teeth. These images were
acquired to evaluate whether grooves illustrated for adult Ignacius specimen in Fig.
2.41B (bs?) and Fig. 2.41 D-F (bs) are in fact sutures. There is a density difference
between dorsal region of bone and cochlea containing bone, specifically. Thus,
structures illustrated for Ignacius in Fig. 2.41D-F appear to be sutural in that they are a
meeting of two different types of bone, but that in Fig. 2.41B appears to be a meeting of
two different outgrowths from same bone. The bone forming the medial process of the
petrosal appears to extend over entire dorsal surface of bones housing cochlea in this
specimen, and thus likely represents part of temporal bone (see text). Numbers and
abbreviations: bs – bullar suture; Ptr – petrosal; rtp – rostral tympanic process; s1 – first
(anterior) septum; s2 – second septum: forms medial to s1.
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