100 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



the postzygapophyses of the preceding vertebra, as shown in the drawing of the 

 skeleton (plate 30). The postzygapophyses slightly overhang the centrum in the 

 distal caudal region. . Most of the caudals have well-defined oblique chevron facets, 

 as shown in figure 1, plate 22. These become less and less well defined as the distal 

 end of the tail is approached. 



The tall neural spines and long slender chevrons of the anterior half of the 

 series would indicate a high thin tail for this part, but it becomes more and more 

 cylindrical toward the end. The whole apparently indicates, in life, a tail capable 

 of great transverse flexibility for the proximal portion, with a more sinuous move- 

 ment possible for the distal half. 



Measurement!: 



of caudal 



vertebrae c 



)f Ceratosaurus nasicornis 



Marsh. 







Number of vertebra 

 in series. 



Greatest 

 length 



of 

 centra. 



Greatest 

 height 

 of ver- 

 tebra 

 over all . 



Greatest 

 length 



of 

 chevron. 



Number of vertebra 

 in series. 



Greatest 

 length 



of 

 centra. 



Greatest 

 height 

 of ver- 

 tebra 

 overall. 



Greatest 



length 



of 



chevron. 



1 



mm. 

 79 

 80 

 80 

 79 

 78 

 76 

 81 

 79 

 78 

 78 

 77 

 76 

 74 



mm. 

 278 



mm. 



27 2 



mm. 



mm. 



mm. 



2 



28 3 ... 



55 

 51 

 48 

 49 

 48 

 50 

 47 

 47 

 43 

 41 

 40 

 39 

 39 

 36 

 35 

 30 

 29 

 32 

 28 

 26 

 24 

 20 

 18 

 18 



65 





3 



244 

 250 

 252 

 249 

 252 

 248 



258 

 221 



29 





4 



30 



54 

 53 

 50 

 47 

 40 

 40 

 - 40 

 37 



53 



5 



31 



49 



6 



32 





7 



33 



43 



8 



34 





9 



35 



34 



10 







36 





11 







37 





12 







38 :... 





13 







39 





24 



14 



152 



l 132 



40 



23 



15 





41 ■ 





16 







42 







17 









43 







18 



62 



58 







44 







19 







45 







20 



106 





46 







21 







47.. 







22 



59 

 62 

 58 

 58 

 56 







48 







23 







49 







24 







50 







25 







51 







26 '. 





















1 Chevron placed. 



2 Vertebra restored. 

 CHEVRONS. 



s Vertebra placed. 



The chevron bones present in the type are the second to the ninth, and the distal 

 series of 12 from the twenty-ninth to the fortieth. All were found articulated 

 excepting the fifteenth, which was placed as shown in plate 30. It was found 

 detached, but in a block of sandstone containing other bones of the skeleton, and 

 on the basis of this association was considered as belonging to the type. The 

 anterior chevrons have suffered loss of parts since the drawing was made for Marsh, 

 as may be seen at once by comparing figure 1, plate 22, with upper figure, plate 27. 



