BSPECIALLY MYCTOPHOIDS 9 
The sphenotic makes up the postero-dorsal corner of the orbit, contacting the 
pterotic posteriorly and the frontal dorso-medially. The pterotic forms the postero- 
lateral border of the skull-roof and is inclined ventro-laterally. The anterior region 
of the hyomandibular facet is composed of sphenotic with the possibility of a con- 
tribution from the prootic, while the main part of the facet is formed from pterotic. 
The epiotics form the postero-lateral region of the occipital border of the roof bound- 
ing the parietals posteriorly. The dorsal region of the epiotic is thickened to produce 
a knob of bone with which the dorsal limb of the post-temporal articulated. 
Within the posterior region of the orbit, traces of median bony elements are 
observable which may correspond to an orbitosphenoid and a basisphenoid, but may 
simply be other neurocranial bones which have become displaced. 
Jaws and suspensorium. The dermal upper jaw is extended into a long thin 
rostrum, with contributions from the palate and neurocranium. The hyomandibular 
has an elongated head with a lateral crest passing back to the rear edge of the bone. 
The hyomandibular is held vertically and the quadrate condyle is immediately below 
the occiput. The quadrate is a shallow, triangular bone with an expanded and 
extremely well ossified ventral condyle. The condyle is transversely orientated and 
fits into a shallow articular facet. The quadrate meets the ectopterygoid anteriorly 
and the metapterygoid dorsally. The metapterygoid is clearly visible overlapping 
the anterior regions of the lateral face of the hyomandibular. The anterior edge of 
the metapterygoid is produced into an oblique thickened ridge which is continuous 
with a ridge on the postero-dorsal part of the ectopterygoid. The ectopterygoid is 
thin and elongated, posteriorly contacting the quadrate and the metapterygoid, and 
anteriorly the palatine. The connection with the palatine is in the region of the 
lateral ethmoid at the anterior end of the orbit. The palatine continues forwards as 
a direct extension of the ectopterygoid along the entire length of the rostrum. The 
palatine bone is supported medially by the extended mesethmoid and vomer and 
takes the form of a thin vertical lamina of bone. Its ventral edge bears a single 
row of relatively large, slightly recurved needle-like teeth. 
The dermal upper jaw is composed of premaxilla and maxilla, although it is practic- 
ally impossible to determine to what extent the maxilla enters the oral border. It 
would appear that at least the anterior two-thirds of the gape is produced by the 
premaxilla and possibly more. The dermal upper jaw bears a marginal row of 
minute teeth. 
The mandible is long and shallow bearing two rows of teeth, a marginal row of 
minute teeth and an inner row of larger teeth approaching the size and form of those 
on the palatine. Almost all of the mandible is composed of dentary, the articular 
being a relatively small component. The articular facet is shallow, despite the size of 
the quadrate condyle, and there is no coronoid or retroarticular process. 
Operculay bones. The preoperculum is narrow and upright with a slight basal 
expansion. The anterior edge of the preoperculum abuts against the posterior face 
of the hyomandibular crest dorsally, and against the rear edge of the quadrate 
ventrally. The operculum is large, slightly deeper than it is long with a rounded 
upper and posterior margin and a straighter, postero-dorsally inclined ventral edge. 
The suboperculum is large with rounded ventral and posterior edges. Dorsally it is 
