144 
J. Long 
theropod dinosaur by direct comparison with that 
of Allosaurus fragilis (Madsen 1976) and other 
theropods (casts and material examined by the 
author include Tyrannosaurus, Tarbosaurus, 
Albertosaurus, Deinonychus, Allosaurus and isolated 
omithomimosaur pedal phalanges from the Judith 
River Formation, Alberta) differing from A. fragilis 
only by its smaller size and slight proportional 
differences, such as the depth of the proximal end 
(Figure 1 A, E). The phalanges of the manus in 
Allosaurus are all much narrower with more 
slender shafts than observed in the Gingin bone. In 
addition, a cast of the bone was shown to various 
dinosaur experts (Dr Philip Currie, Dr Peter 
Dodson, Mr Gregory Paul) in the U.S.A. at the 
Dino Fest Conference (Indianapolis, March 1994) 
who all commented that it appeared to be "an 
indeterminate theropod pedal phalange" bone . 
In general the phalanges of ornithopods reflect 
their broader feet proportions in having wider 
phalanges with flatter dorsal and ventral surfaces. 
Direct comparisons were made with casts of 
Muttaburrasaurus, Hypsilophodon, Saurolophus, 
Corythosaurus and lguanodon. Only the fourth digit 
proximal phalanx in Allosaurus has the same 
proportions as the Gingin bone in that the proximal 
face is relatively triangular in outline, much deeper 
than the distal end, and lacks a distinct vertical 
median crest (Madsen 1976, figs 54, 55). 
The size of the Gingin bone is about half 
the length of the equivalent element in Gorgosaurus 
libratus (WA Museum cast of 1933 Sternberg 
specimen) and approximatly half the size of that in 
Allosaurus fragilis. Based on the adult sizes of 
these camosaurs it is estimated that the Gingin 
theropod may have been about 4 metres maximum 
length. 
Figure 1 Theropod pedal phalanx, proximal element 
of fourth digit, left side. WAM 
92.7.1.Molecap Greensand (Late Cretaceous), 
Molecap Quarry,Gingin, Western Australia. 
Specimens shown in A, dorsal; B, ventral; C, 
left lateral; D, distal and E, proximal views. 
DISCUSSION 
In its robust nature the specimen differs from the 
slender phalanges of advanced theropods like 
dromaeosaurids, oviraptosaurids, troodontids and 
Figure 2 Comparison between the left fourth pedal proximal phalanx in Allosaurus fragilis (A-D) and the Gingin 
theropod (E-H). A, E, lateral views; B, F, ventral views, arrow points to flexor tubercle; C, G, proximal face; 
D, H, distal view of articular condyles. A-D after Madsen (1976). 
