v 
_ BARYONYX WALKERI 
| On the lateral side of the proximal expansion, where it begins to 
‘narrow into the shaft, are two obvious areas of muscle attachment. 
Immediately posterior to the apex of the deltopectoral crest is a low, 
lightly rugose hump; this is presumed to have been the point of 
insertion of the deltoides clavicularis muscle (cf. Norman 1986: 
338). A little lower down and more posterior in position, indeed 
‘almost in the centre of the lateral surface, is a large shallow depres- 
sion with a distinct raised border below and on either side; this 
probably served as the point of origin of the brachialis muscle (cf. 
! orman 1986, loc. cit.). 
At the distal end of the humerus the ectepicondyle is well ex- 
Be ided, The lower margins of the entepicondyle and the 
ectepicondyle form an angle of approximately 45° with each other, 
: nd their facets for articulation with the radius and ulna respectively 
are subequal in length (the ectepicondylar facet being just a little 
i onger). In Dilophosaurus the humeral shaft is less straight than in 
Baryonyx, and inAllosaurus it is even more curved. The two ends are 
ore offset in Dilophosaurus than in Baryonyx. 
ADIUS (Fig. 33). Both radii are preserved, the left complete but 
the right lacking a section of the shaft so that the two ends are no 
longer connected. The radius is a short, straight, stout bone, not 
distinguished by any remarkable features. It is 225 mm long and 
erefore only 49% of the length of the humerus. The proximal end 
is flattened and expanded, its profile being convex in side view; it 
apers smoothly into the roughly cylindrical shaft, which continues 
to taper slightly until it reaches the less expanded distal end. The 
jatter differs from the proximal end in that it is narrower and not 
| attened; in end view it appears triangular with one corner extended, 
the longest side (in the plane of expansion) being almost perpendicu- 
ar to the plane of flattening and expansion of the proximal end. The 
distal end-surface is perpendicular to the axis of the bone and has a 
Shallow convexity at its centre. 
45 
ig. 33 Baryonyx walkeri, holotype, BMNH R9951; left radius. A, lateral view; B, posterior; C, medial; D, anterior: E, proximal; F, distal. x 0.25. 
ULNA (Fig. 34). Only the left ulna is preserved, almost complete 
and 283 mm long; thus it is considerably longer (61% of the length 
of the humerus) than is the radius. The ulna, unlike the radius, is 
distinctly bowed. The proximal end bears an unusually powerful 
olecranon, projecting posteromedially beyond the head of the bone. 
The articulating surface for the humerus projects anteriorly (making 
an angle of about 130° with the olecranon projection when viewed 
from the proximal end) and has a concavely curved anterior profile 
distal to its apex. The lateral surface of the proximal end actually 
consists of two surfaces, one facing obliquely forwards and the other 
obliquely backwards so that they together make a right angle. This 
angle forms a powerful projection which, unfortunately, has been 
severely damaged. 
The most unusual feature of the ulna is the broad expansion of the 
distal end. This is essentially in the transverse plane, but the greatest 
part of the expansion is on the medial side where the bone has been 
extended anteromedially and, at the same time, somewhat dorsally. 
Although this medial expansion is distinctly more slender than the 
central part of the ulna, the bone thickens again towards the medial 
margin so that the articulating surface is of almost constant width. 
There is also a rather less prominent anterolateral expansion of the 
lateral side, but here the bone becomes appreciably thicker, so that 
this part of the articulating surface is virtually semilunate. The distal 
profile of the ulna, in anterior or posterior view, is markedly convex. 
CARPUS. 
served. 
No recognisable remains of the carpal bones are pre- 
MANUS (Figs 35, 36). The metacarpals too have all been lost, but a 
few phalanges are preserved (including three unguals), and some are 
in excellent condition. They include the original and famous ‘Claw’, 
i.e. a huge ungual, together with what is probably the phalanx with 
which it articulated; three phalanges found in articulation 
