» BARYONYX WALKERI 
the lateral (fibular) extends about 15 mm below the medial (tibial) 
' They are separated by deep intercondylar grooves on both anterio1 
| and posterior surfaces; the anterior groove is V-shaped, while the 
| posterior is broader and U-shaped. The tibial condyle, seen in 
/ anterior or posterior view, appears to be displaced medially from the 
line of the shaft; it is greatly expanded anteroposteriorly (though 
) somewhat obliquely) but is relatively narrow from side to side. The 
/ fibular condyle, by contrast, lies more or less on the line of the shaft 
| and is less expanded anteroposteriorly. On its posteromedial surface 
arises a prominent longitudinal flange; this is equivalent to the 
‘blocky protuberance’ described in Allosaurus by Madsen (1976: 
43) and the “ectocondylar tuber’ described in Dilophosaurus by 
' Welles (1984: 137). The deep concavity between this flange and the 
fibular condyle itself is the trochlea fibularis of Currie & Zhao 
/ (1993). A longitudinal groove, deep and V-shaped, runs up the 
“medial surface of the distal part of the shaft; apart from this, the 
preserved portion of the shaft is in too poor a condition to merit 
description. 
TIBIA. One fragment is recognisable as a distal part of a tibia, but 
“it is too badly crushed to be described. 
|FIBULA (Fig. 42). The right fibula is in good condition and lacks 
jonly its extreme distal end; it is 510 mm long as preserved. The 
' proximal end is broad and flat and expanded anteroposteriorly; the 
expansion is mostly towards the rear, so that the posterior profile is 
)weakly concave. The lateral surface is weakly convex and the medial 
‘surface weakly concave (the latter would have faced the tibia). The 
elongated, weakly crescentic end-surface is just a little thicker 
anteriorly than posteriorly. The anteromedial edge of the shaft, just 
below the head, is slightly thickened for the attachment of the 
| tibiofibular ligaments, but this thickening is less well developed in 
Baryonyx than in Allosaurus, Dilophosaurus and certain other 
‘theropods. Seen in lateral or medial view, the proximal end tapers 
‘rapidly distad (with a very weakly concave profile both anteriorly 
and posteriorly) into a straight, slender, rod-like shaft; the shaft 
continues to taper more gently, and its anterior and posterior margins 
‘eventually run parallel to each other, after which the fragment is 
\terminated by the distal break. 
_ The weak concavity of the medial surface of the proximal end, i.e. 
\the medial sulcus, is continued distad into the medial surface of the 
‘shaft, eventually becoming a relatively deep V-shaped trough that 
\terminates suddenly about half-way down the bone (as preserved). 
/Below this the shaft is almost circular in cross-section for a short 
‘way but then becomes concave again on the medial side, so that the 
‘broken end-surface is clearly crescentic. This medial sulcus is better 
developed inAllosaurus, Torvosaurus, troodonts and dromaeosaurs; 
in Allosaurus it is continuous all the way down the shaft. 
/ASTRAGALUS. A flattened piece of bone compares well with the 
‘ascending process of the left astragalus of Allosaurus, but is too 
broken and irregular in outline to merit description. 
|CALCANEUM (Fig. 43). The right calcaneum is virtually complete. 
Un lateral or medial view it is semilunate, with a weakly concave 
‘proximal profile and a strongly convex distal profile. In proximal 
‘view, the proximal surface is thick and rounded at the anterior end 
but tapers to a sharp point posteriorly; the surface itself is weakly 
concave to receive the distal end of the fibula. The lateral margin of 
this proximal surface is not higher than the medial margin, in which 
respect Baryonyx is like Torvosaurus, but unlike Allosaurus and 
\Sinraptor. 
The lateral surface is almost flat and very slightly dished. The 
jmedial surface is convex and bears, at its anterior end, two deep 
jrounded hollows, with a slight protuberance between them. One of 
Fig. 42 Baryonyx walkeri, holotype, BMNH R9951; right fibula. A, 
medial view; B, lateral. x 0.25. 
these is above and slightly anterior to the other; they are the facets for 
the two lateral tuberosities of the astragalus, the proximal facet being 
the larger of the two. The remaining part of the medial surface forms 
a Shallow facet for the reception of the tibia; this facet is much deeper 
and more cup-shaped in Allosaurus. 
PEs. The collection includes two damaged distal ends of metatar- 
sals, with typical broad, rounded articular surfaces and with fairly 
well-developed ligament pits. They could be metatarsals II, III or 1V 
of either foot. 
Another fragment is the basal part of an ungual from the foot, as 
indicated by its large radius of curvature and flattened ventral 
(internal) surface. 
