OSTEOLOGY OF CARNIVOROUS DINOSAURS. 



45 



this border of the ilium. The upper ends of the neural spines are roughened and 

 slightly expanded transversely. 



The principal dimension of the sacral vertebrae are given in the accompany- 

 ing table of measurements below: 



Measurements of Antrodemus sacral vertebrae in millimeters. 



No. 4734, 

 U.S.N.M. 



No. S423, 

 U.S.N.M. 



No. &40o, 

 U.S.N.M. 



No. &367, 

 U.S.N.M. 



Length of centrum: 

 Length of centrum: 

 Length of centrum: 

 Length of centrum: 

 Length of centrum: 

 Width of centrum: 



Total length of five coossified vertebrae 



Greatest expanse of transverse processes of S t . 



, mid height. 

 , mid height. 

 . mid height. 

 , mid height . 

 . mid height, 

 mid height.. 



116 

 104 

 104 

 108 

 104 

 108 

 536 



*90 

 99 

 104 

 120 

 114 

 117 

 540 



120 

 96 

 107 

 125 

 118 

 125 

 575 

 190 



152 

 132 

 146 



i Estimated. 



Caudal vertebrae. — Though the United States National Museum collections do 

 not contain a complete articulated caudal series of Antrodemus, after a study of the 

 incomplete tail of No. 4734, U.S.N.M., it is estimated that the entire series would 

 consist of at least 45 caudal vertebrae. In number, therefore, it is intermediate 

 between Gorgosaurus, with Lamb's estimate of 36 and Tyrannosaurus, with 

 Osborn's estimate of 53. 



In specimen No. 4734, U.S.N.M., there are vertebrae present from all parts of 

 the tail except the extreme tip, but most of these are poorly preserved. When first 

 found in the quarry, as all of the available evidence appears to indicate, the caudal 

 series of this individual was articulated with the sacrum and nearly if not quite 

 complete. Unfortunately, before it was recognized as pertaining to so perfect a 

 skeleton, the bones were quarried out and thrown on to the pile of detrital material. 

 In the subsequent attempt to salvage these vertebrae from the "dump" many of 

 the vertebrae were entirely lost, as shown by the impressions in the sandstone 

 blocks, and those caudals recovered in most instances were so mutilated by the loss 

 of processes and other parts as to destroy much of their original value. However, 

 having vertebrae present from different sections of the tail, gives some information 

 of the changes that take place from front to back and it is especially valuable for 

 comparison with the quite different series of Ceratosaurus. From this "dump" 

 material 33 caudal vertebrae are recognized. 



With specimen No. 8367, U.S.N.M., there are eight caudal vertebrae, seven of 

 which represent the first seven of the caudal series, as shown in figure 21. (Quarry 

 Nos. 10, 9, 8, 7, 6, 5, and 4.) The remaining caudal (quarry No. 15) is from the 

 mid-region of the tail. 



The characteristics of the anterior caudal vertebrae will be largely described 

 from specimen No. 8367, U.S.N.M. These vertebrae are heavy and stout, the 

 first four having centra that are higher than long. In passing backward they soon 

 assume a lengthened cylindrical form as the diminution in length is less rapid (see 

 table of measurements) than the decrease in height. 



