| BARYONYX WALKERI 
| 
| 
ig.31 Baryonyx walkeri, holotype, BMNH R9951; elements of pectoral 
girdle, including sternum. A, left scapula in lateral view; B, left coracoid 
in lateral view; C, sternum in ventral view. x 0.25. 
43 
The thickened posterior edge of the lower part of the scapula, as 
it approaches the glenoid, bears a low but distinct muscle ridge 
running parallel to its lateral margin (Welles’ ‘slight rugosity’, 1984: 
127). 
CORACOID (Fig. 31B). Both coracoids are preserved, but in neither 
has the anterior region escaped damage. The whole of this region is 
missing in the right coracoid; in the left, however, sufficient remains 
to determine its anterior extent but not the shape of the margin. 
As usual in theropods, the plate-like coracoid is medially concave 
and laterally convex, continuing the line of curvature of the adjacent 
scapula. The perfectly preserved posterior region is shaped like a 
hatchet and projects directly backwards, not at all towards the 
midline as in some other theropods. The robust articular region bares 
dorsally the semicircular glenoid facet and the pear-shaped sutural 
surface for the scapula, its junction with the medial surface being 
marked by a prominent rugose ridge. As mentioned above, the line 
of articulation between scapula and coracoid is zigzag-shaped in 
lateral view. Ventral to this articulation the coracoid plate is perfo- 
rated by the coracoid foramen, circular in lateral exposure, 
pear-shaped in medial exposure and approximately 25 mm in diam- 
eter. 
Fore-limb 
As is typical of theropods, all three major bones are short, relative to 
the general size of the animal; but they are also remarkably robust 
and wide, relative to their shortness, with stout shafts and broadly 
expanded ends. 
HUMERUS (Fig. 32). The left humerus is essentially complete, 
although the medial side of the shaft is somewhat crushed. The right 
humerus shows a similar state of preservation, but lacks almost the 
whole of the ectepicondyle (ulnar condyle). The element is 463 mm 
long (Charig & Milner 1990). 
The first impression is of a stout and stubby bone, with two 
broadly expanded ends connected by a straight and relatively short 
shaft; the maximal width of the proximal end is 242 mm and of the 
distal end 183 mm. The two ends, however, are flattened to a 
significant degree; the distal expansion, in particular, appears very 
thin in end view. The plane of the distal expansion is offset with 
respect to that of the proximal expansion by some 30°. At the 
proximal end there is considerable expansion of the deltopectoral 
crest on the anterior side, and a greater expansion of the internal 
tuberosity (the entotuberosity of Welles 1984) on the posterior side. 
Although the deltopectoral crest projects from the anterior side of 
the bone, its apical portion is bent round anteromedially so that the 
lateral surface of the proximal expansion is distinctly convex and its 
medial surface correspondingly concave. 
The distance between the upper end of the humerus and the apex 
of the deltopectoral crest is approximately 43% of the entire length 
of the element, while the deltopectoral crest as a whole constitutes 
51% of that length. Between the deltopectoral crest and the internal 
tuberosity lies the head of the humerus, a thickened region that 
articulated with the glenoid. On the medial surface of the proximal 
expansion, about half-way between the head and the apex of the 
deltopectoral crest, is a distinct ridge some 35 mm in length running 
along a line that is directed towards the centre point of the shaft. This 
ridge, which is clearly present on both humeri, is a rounded hump 
distally and tapers proximally to become lower and narrower as it 
approaches the edge of the bone. To the best of our knowledge, no 
similar structure has been found elsewhere; it may be a prominent 
insertion for the pectoralis muscle. 
