BARYONYX WALKERI 
showing also vomers. x 0.5. 
however, that our knowledge of the maxillary dentition is 
restricted to the first 7 teeth). 
The extremely fragile, laminar nature of the post-dentary bones in 
the lower jaw. 
The lack of co-ossification between the elements, except in the 
midline and in the braincase. 
The last character suggests that R9951, despite its great size, was 
juvenile, from which we might deduce that the fully mature animal 
as probably much larger still. The possibility that a member of the 
dinosauridae (see p. 55) might attain a truly vast size is confirmed 
Stromer’s illustrations (1915) of the dentary of Spinosaurus 
gyptiacus, an element twice the linear size of that of Baryonyx. 
REMAXILLA (Fig. 2). Both premaxillae are preserved, firmly 
med.r id.p 
i g-2 Baryonyx walkeri, holotype, BMNH R9951; snout. A, conjoined premaxillae in dorsal view; B, same, right lateral; C, premaxillae in palatal view, 
sutured together; the median suture between them is clearly visible 
on the dorsal surface, though it fades out towards the rear. Both 
elements are complete anteriorly but broken off behind. The pre- 
maxillae (as preserved) are not fused to any other elements; each, 
however, has (or had) a complex articulation with the maxilla. 
The snout is unlike that of most other known dinosaurs, in which 
an ascending process rises from the very front of the conjoined 
premaxillae and forms the rounded anterior border of the external 
nares. Here, by contrast, the snout is long and low; the equivalent 
process originates 172 mm behind the tip of the snout and is 
directed almost horizontally backwards. Thus the heavy, robust 
snout formed by the conjoined premaxillae is seen in lateral view to 
bifurcate posteriorly into two rami on each side, a short one below 
(the main body of the premaxilla) and a longer one above (the 
