100 



BULLETIN 89, UNITED STATES NATIONAL MUSEUM. 

 Measurements of dermal plates of Stegosaurus stenops No. 4334. Type. 



Plate 







Greatest 



Greatest 



Plate 







Greatest 



Greatest 



Xo. 





Greatest 



length 



trans- 



No. 





Greatest 



length 



trams- 



(counting 





diameter 



antero- 



verse 



(counting 



Greatest 

 height. 



diameter 



antero- 



verse 



back- 



height. 



antero- 



posterior 



width 



back- 



antero- 



posterior 



width 



ward 



posteri- 



of rough- 



of rough- 



ward 



posteri- 



of rough- 



of rough- 



from the 





or^. 



ened 



ened 



from the 





orlv. 



ened. 



ened 



skull). 







base. 



base. 



skull). 







base. 



base. 





mm. 



mm. 



mm. 



mm. 





mm. 



mm. 



mm. 



mm. 



' 1 



97 



60 







10 



2 610+ 



535 



423 



40 



2 

 3 

 4 

 5 



119 

 134 

 172 

 1S5 



45 

 S2 

 75 

 76 



36 



17 



11 

 12 

 13 

 14 





560 

 610 

 695 

 785 





55 





590 

 590 

 720 



55 

 60 











760 



S7 



6 





191 



96 





3 15 



627 



630 



450 



105 



7 

 S 

 9 





* 323 



430 



205 

 ISO 



105 



'16 

 3 17 

 <1S 



335 

 225 

 537 



410 

 290 



300 

 220 

 115 







50 

 65 



2 610+ 













1 Plates with odd numbers pertain to left row, even to the right row. 



2 Estimated. 



3 Dermal elements not in sequence. 

 * Dermal spine. 



Position of plate centers in relation to underlying vertebrae. 



Plate 

 No. 



(counting 

 back- 

 ward 



from the 

 skull). 



Vertebrae in vertebral 

 column. 



Plate 

 No. 

 (counting 

 back- 

 ward 

 from the 

 skull). 



Vertebrae in vertebral 

 column. 



Plate 

 No. 



(counting 

 back- 

 ward 



from the 

 skull). 



Vertebrae in vertebral 

 column. 



1 

 2 

 3 

 4 

 5 



Atlas. 



Axis. 



Third and fourth (between) . 



Fourth and fifth (between) . 



Fifth and sixth (between) . 



6 



7 

 8 

 9 



Sixth and seventh (het ween) . 

 Eighth. 

 Tenth. 



Thirteenth and fourteenth 

 (between) . 



10 

 11 

 12 

 13 

 14 



Seventeenth. 

 Twentieth. 

 Twenty-fourth. 

 Second caudal. 

 Eighth caudal. 



Morphology op Plates. 



Lull 1 has given the following interesting explanation of the development of 

 the dermal plates: 



Upon comparing a given plate with a scute of a crocodile or that of such a dinosaur as Antylosaurus 

 or Stegopelta it at once becomes apparent that the great expanse of the first represents merely an enor- 

 mous hypertrophy of the median ridge or carina of the latter. This expanse is practically alike on both 

 sides, with blood-vessel impressions and no indication that either one side or the other was in contact 

 with the creature's flesh. On the other hand, the base, the morphological equivalent of the body of 

 the scute in crocodile or Ankylosaur, is always somewhat asymmetrical, even when divided into two 

 portions by the longitudinal cleft of those of the cervical region. This base in the great dermal plates 

 particularly is extremely rugose, implying either a heavy pad of cartilage or a very thick connective 

 tissue between the plate and its underlying skeletal support. There is in no instance any indication 

 of a true articulation with the subadjacent bones. 



Amer. Joum. Sci., vol. 29, 1910, pp. 204-205. 



