104 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



Comparative measurements of radii, Ceratosaurus and 

 Antrodemus. 



Ceratasaurm 

 nasicornis, 

 No. 4735, 

 U.S.N.M. 



Antrodemus 



miens. 



No. 4734, 



U.S.N.M. 



Greatest length of radius 



Greatest transverse diameter of 



proximal end 



( treatest transverse diameter of 



distal end 



150 

 48 

 36 



222 

 56 

 40 







Forefoot. — As mentioned above a complete 

 fore foot of Ceratosaurus is as yet unknown, 

 though the articulated left manus gives a fairly 

 good idea of its structure. The phalangial 

 formula, however, remains to be definitely 

 determined. With the tj'pe the following 

 bones of the fore feet are preserved: Meta- 

 carpals I, II, III, IV, and proximal phalanges 

 of digits 2, 3, and 4 of the left nianus; meta- 

 carpals IV, distal halves of metacarpals I and 

 II, and proximal phalanx of digit 2 of the 

 right foot. 



Carpus. — Ossified carpal bones are unknown 

 in Ceratosaurus, and although the articidated 

 foot mentioned above was foimd in position 

 in relation to the distal ends of the radius 

 and ulna (fig. 60), no carpal ossifications 

 were found in the intervening matrix. This 

 would appear to indicate an unossified carpus, 

 for this specimen is an old individual, as 

 clearly demonstrated by the coossified pelvic 

 and metatarsal bones. 



Metacarpus. — The metacarpus consists of 

 four bones, as shown by the foot found in 

 Fig. eo.-LEFT KADius, ULNA AND FOEE FOOT OF Cera- pjace 33 dcplctcd in figure 60. The two me- 



TOSAURUS NASICORNIS MaKSH. NO. 4735, U.S.N.M. . , 1 j_ 1 "L j. 1 



TypE-j NAT. SIZE, ij , BADins; 17, Ulna, I, II, m, diau metacarp;ds are moderately robust ele- 

 and IV, METACARPALS ONE TO FOUR. SHOWN AS jneuts, but I and IV are much reduced. 



FOUND I.\ THE M.iTRLX, SEVERAL OF THE BONES NOT -- it- 1 il -il Tljl 



ENTiEELT UNCOVERED. MctacarpaJ 1 IS a short bone with slight!}^ 



expanded proximal and distal ends. The dis- 

 tal end is deeply grooved and turns inward away from the central axis of the 

 foot as in most other Theropod dinosaurs. This diversion is due to the unequal 

 development of the articulating facets, the outer one bemg the larger and extending 

 farther forward, as in Gorgosaurus. It is unlike Antrodemus in this respect, where 

 a bend in the shaft diverts it inward. Both facets on tlais end curve down and 



xW^**' 



