OSTEOLOGY OF CARNIVOKOUS DINOSAURS. 



101 



/■--) 



The anterior chevrons ot^Ceratosaurus are especially long, slender, and with but 

 slight backward curve. They articulate intervertebraUy with beveled articular 

 facets on the ends of,'theT,centra. 

 They begin between the first and 

 second vertebrae and continue 

 to the forty-first caudal. The 

 second, the longest one of the 

 series, measures 254 mm. in 

 length. The haemal opening 

 between the branches forming 

 the Y-shaped proximal ends are 

 very much constricted trans- 

 versely. The proximal end is <> 

 very slightly expanded, but it ,' 

 forms a bridge across the upper j 

 boimdary of the haemal open- \ 

 ing. These chevron bones of 

 Ceratosaurus can be readily dis- 

 tinguished from the homolo- 

 gous elements of other American 

 Theropodous dinosaurs by 

 their greater relative length and 

 slenderness, and by the very 

 sUght exjiansion of their proxi- 

 mal and distal ends. 



The distal series are short, 

 with expanded free ends that 

 curve decidedly backward. 

 Chevrons 29 to 34, viewed from 

 the side, show a spur-like pro- 

 longation that extends well up- 

 ward between the two centra. 

 In a lesser degree the anterior 

 chevrons of Tijrannosaurus ' 

 have a somewhat similar devel- 

 opment, as they do also in Gor- 



gOSaurUS hbratUS Lambe.- ^j^, ,53 _LEfT fore limb and foot of ceratosaurus nasicornis Maesh. 



jjjgg Cat. No. 4735, U.S.N.M. Type. About J NAT. size. Viewed 



FROM THE front. GREATER PART OF THE CORACOID, DISTAL END OF 



TJlOTOcic ribs. The thoracic scapula, humerus, carpus, and terminal phalanges of Ceratosau- 



. f /~i 4 ^^^ UNKNOWN. These are restored here from allied forms. 



ribs 01 CeVQtOSdUTUS are un- this figure was first published by Marsh as the fore limb of 



known at this time, except the allosaurus feagius. (after marsh.) 



right articulating with presacral Xo. 21, shown as found in position in plate 21, 



figures 1 and 2. 



' Osbom, H. F. Bull. Amer. Mus. Nat. Hist., vol. 35, 1917, pi. 27. 

 » Lambe, L.M. Mem .100 Geo:. Surv. Canada, 1917, fls. 19. 



144035—20 8 



