Download Brief description of non ear region anatomy of Bothriogenys, DUPC

Brief description of non ear region anatomy of Bothriogenys, DUPC
5248. The partially-preserved, single sagittal crest (Fig. 2.2) starts at the junction
of the two frontal crests and extends to the nuchal crest; a deep crease lies
between the frontal crests. The two temporal crests (Fig. 2.1) start superior to
the external acoustic meatus and meet the nuchal crest dorsally. The external
acoustic meatus extends several centimeters superior to skull base. The
squamosal forms both postglenoid and posttympanic processes, which do not
meet ventrally, and both are fused with the elongate, bony meatal tube. The
postglenoid foramen (diameter ~ 2 mm) is wedged deeply between the meatal
tube and the postglenoid process. The long axis of the glenoid fossa (Fig. 2.3) is
oriented such that the lateral margin is slightly more anterior than the medial
margin. No significant preglenoid process exists. Superior to the glenoid fossa
is a large supraglenoid foramen (~ 2 mm in diameter), which, on the right side
only, has a second, smaller foramen adjacent to it (Fig. 2.2).
The occiput is tall and mediolaterally narrow (Fig. 2.4). The external
occipital crest is subtle; it is best preserved at its base but extends to the superior
aspect of the occiput where it ends in a “V” shape. On either side of it superiorly
are two deep depressions that are holes but may not have been true foramina.
The superior edge of the exoccipital is distinct from but fused to the squamosal.
The slit-like mastoid foramen is roofed superiorly by a short, straight shelf of
squamosal (this resembles the morphology of Pakicetus inachus, UM-GSP
084). The occipital condyles are triangular in distal view; superior to them (Figs.
2.1, 2.4) is a small dorsal condyloid foramen. The large foramen magnum is
marked superiorly by a small nuchal tubercle (not preserved on right).
The occipital condyles are separated at the ventral midline (Fig. 2.3) by a
very small space. Both extend anteriorly forming flexion stops (Janis and Scott,
1987). Just lateral to each of these is one large foramen that Schmidt (1913)
called the condyloid foramen. This foramen (~ 10 mm in diameter), the only one
in the area, is more likely the hypoglossal foramen.