48 
Fig. 36 Baryonyx walkeri, holotype, BMNH R9951; three articulated phalanges from digit II or III of left manus. A, proximal and middle phalanges in 
dorsal view; B, digit with ungual phalanx, left lateral; C, proximal and middle phalanges, ventral; D, proximal end of ungual; E, distal end of middle 
phalanx; F, proximal end of middle phalanx; G, distal end of proximal phalanx; H, proximal end of proximal phalanx. x 0.5. 
excavated ventral surface. This deep excavation is the brevis fossa, 
and the ventromedially directed ridge which partly encloses it is the 
brevis shelf. The ventral part of the otherwise concave medial surface 
is broadly convex, with faint subparallel ridges, and it appears to 
terminate posteriorly in a pronounced thickening; the rest of the 
ventromedial blade is very slender. The brevis shelf and the iliac 
blade are of uniform and approximately equal thickness along their 
length; the brevis shelf thins towards its ventral edges. The ventro- 
lateral ridge, by contrast, is much stouter and smoothly rounded, and 
it thickens anteriorly in the direction of the acetabulum. 
The iliac blade as a whole is of almost uniform thickness, and its 
lateral surface is strongly dished anteroventrally where it thickens 
towards the (missing) anteroventral termination. Further, its medial 
surface bears two scars for the direct attachment of the truncated 
diapophyses of the sacral vertebrae: one lies more or less dorsal to 
the pubic peduncle and is broadly U-shaped, the other lies dorsal to 
the ischiadic peduncle and is narrow and curved. (The distance 
between these two scars suggests that there must have been another 
scar midway between them, where the bone of the blade is missing 
A.J. CHARIG AND A.C. MILNER 
and the mould of its medial surface is not well enough preserved toy 
indicate its presence.) These scars have no distinct border, but are), 
characterized by their finely rugose surface, easily distinguishable 
from the smooth surface of the rest of the blade. It would be expected 
that the most ventral portion of the blade would bear another row of} . 
scars, marking the distal attachment of what are usually calledy 
‘sacral ribs’ but which generally consist of no more than the capitu-/ 
blade is missing, but the mould of its medial surface shows two)». 
prominent and well-defined scars which presumably mark the) 
attachment of the last two sacral ribs. | 
The pubic peduncle is very robust; its articular surface forms 4} ., 
narrow triangle, the short side being the acetabular edge. The surface e! 
