A NEW RESTORATION OF STEGOSAURUS. 



By Charles W. Gilmore, 



Assistant Curator of Fossil Reptiles, United States National Museum. 



In a recent paper * I have reproduced ten restorations of Stego- 

 saurus as depicted by various authorities between the years 1891 and 

 1912. These show a considerable variety of interpretations, and are 

 of interest as exhibiting the diverse opinions held regarding its prob- 

 able appearance in the flesh, and especially as to the arrangement of 

 the dermal armor, which forms such a conspicuous feature of the 

 external anatomy of this curious reptile. Since none of these resto- 

 rations portray fuUy the ideas set forth in the bulletin cited above, I 

 have recently prepared a small model of Stegosaurus one-twelfth 

 linear dimensions, the proportions of the model being based upon 

 careful measurements made from the type-specimen of Stegosaurus 

 stenops Marsh now in the United States National Museum. In this 

 model I have incorporated all of the evidence relating to its external 

 appearance accumulated during several years' study of a large series 

 of Stegosaurian remains, and I believe that the more important facts 

 relating to the proper arrangement of the dermal armor has now been 

 quite fully established. 



Briefly, these facts are: That the dermal plates of opposite rows 

 alternate, not paired; that the largest plate of the series, as shown by 

 two individuals found in place, is above the base of the tail, not over 

 the pelvis; that there are not more than 18 ^ in the complete series 

 of flat plates; that the dermal spines number four, based upon the 

 evidence of association in six individuals ; that the bases of the plates 

 of opposite rows are comparatively close together on either side of 

 the median line of the back; that although the evidence is not con- 

 clusive, there is every probability that the so-called gular ossicles 

 covered the top and sides of the head and neck, as indicated in the 

 model, rather than the throat, as represented in previous restorations. 

 In fig. 1 is shown a drawing of the plates in alternating position, prob- 

 ably made under the supervision of Dr. F. A. Lucas at the time he 



• Charles W. Gilmore, Bulletin 89, U. S. National Museum, December 31, 1914, pp. 122-126, pis. 32-36. 

 ' In Bulletin 89, U. S. National Museum, it was stated "there are not more than 22 and perhaps only 

 20," but after preparing this model to scale I am now convinced that my first estimate was too large. 



Proceedings U. S. National Museum, Vol. 49— No. 2110. 



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