| BARYONYX WALKERI 
y 
| lateral. x 0.5. 
jend. Viewed posteriorly, the quadrate tapers rapidly upwards from 
‘the lower jaw articulation into a narrow shaft that swings a little 
/anterolaterally and then dorsally. It terminates in an expanded knob- 
like head that fitted into the underside of the squamosal; on the 
lateral side of the head is a small, distinct, slightly concave facet. The 
jlateral surface of the broad basal part of the quadrate forms a large, 
\rugose, kidney-shaped concavity which provided an immovable 
)sutural attachment for the quadratojugal. Higher up the shaft is a 
laterally directed ridge, its outer end forming a narrow sutural 
surface, also for the quadratojugal. Between these two quadratojugal 
attachments lay a large, elongated quadrate foramen delimited 
‘medially by the quadrate and laterally by the quadratojugal. This 
foramen is much larger than the equivalent foramen of Allosaurus, 
which is almost entirely enclosed by the quadrate. 
The entire anterior side of the quadrate is extended forwards into 
ja wide pterygoid flange; the medial side of the lower half of this 
‘/flange was presumably applied to the lateral face of the pterygoid. In 
llosaurus this flange is directed obliquely towards the midline. The 
road quadrate condyle, extending transversely mediad from the 
uadratojugal facet, is characterized by a screw-like sigmoid swell- 
ing; this is anterior in position on the medial side but curves round 
elow the condyle to a posterior position on the lateral side. This 
surface, which articulated with the lower jaw, is much wider medi- 
ally than laterally. 
23 
j 
Fig. 9 cont Baryonyx walkeri, holotype, BMNH R9951; occiput and posterior part of braincase, lacking detached left opisthotic. C, anterior view; D, left 
Lower jaw (Fig. 12) 
Parts of both rami are preserved, including: 
Left side: dentary (virtually complete); splenial (fragmentary); 
angular (partial). 
Right side: dentary (a section of the dentigerous bar containing eight 
alveoli, probably nos. 18-25); splenial (complete); surangular 
(fragmentary); angular (partial); coronoid (complete). 
DENTARY (Figs 13, 14). Of all the elements in the mandible, the 
left dentary is the best preserved. It was found broken into two: an 
anterior portion containing the first 26 tooth alveoli and a posterior 
portion containing the last 6. The broken ends had remained in 
contact with each other, but the two parts had undergone a relative 
dislocation to produce a divergence of about 45° from the straight 
line. Nevertheless, their two ends can be fitted together without the 
interpolation of any significant missing portion. There were there- 
fore 32 teeth in each complete dentary, 64 in the entire lower jaw. 
The anterior two-thirds of the dentary (apart from the terminal 
expansion) is essentially elongated from front to back and flattened 
from side to side. Its labial and lingual sides are flat and parallel; the 
dorsal and ventral margins are nearly parallel, but they do converge 
a little anteriorly. The dentigerous dorsal surface is also flat and 
demarcated from the labial and lingual surfaces on either side by a 
