THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE III. VOL. Vlil. 



No. IX.— SEPTEMBER, 1891. 



<D:RX(3rXi<TjL.Xj ^^laariaXjES. 



I. EeSTOKATION of STEaOSAUKUS. 



By Prof. 0. C. Marsh, Ph.D., LL.D., F.G.S., etc. 

 (PLATE XI.) 



IN the American Journal of Science in 1877, the writer described 

 a remarkable extinct reptile from Colorado, under the name 

 Stegosaurus armahis,^ and later a much more perfect specimen of 

 another species, Stegosaurus ungulatus, from essentially the same 

 horizon, in the Jurassic of Wyoming.^ The latter specimen was 

 in fine preservation, and the more important parts of the skull and 

 skeleton, and especially of the remarkable dermal armour, were 

 secured. Subsequently, more than twenty other specimens of these 

 and other species were obtained, so that nearly every part of the 

 osseous structure thus became known, and only portions of the 

 dermal armour were in doubt. A fortunate discovery cleared away 

 most of the doubt in regard to one species, Stegosaurus stenops, as 

 the type specimen had the skull, skeleton, and dermal armour 

 together when entombed, and almost in the position they were when 

 the animal died. 



With this rich material at hand, an attempt has been made to 

 give a restoration of one of the group, and the type specimen of 

 Stegosaurus ungulatus has been selected as the basis. This has been 

 supplemented by a few portions of the skeleton of Stegosaurus duplex, 

 apparently a closely allied species from nearly the same locality, 

 while some other parts, especially of the dermal armour, have been 

 placed in accordance with their known position in Stegosaurus 

 steuops. 



The result is given in Plate XL, which is believed to represent 

 faithfully the main features of this remarkable reptile, as far as the 

 skeleton and principal parts of the dermal armour are concerned. 

 This figure, one thirtieth natural size, is reduced from a larger 

 restoration, one-tenth natural size, made for a lithographic plate 

 to accompany the monograph of the Stegosauria, prepared by the 

 writer for the U. S. Geological Survey. When alive, the animal 

 was about twenty feet in length, and nearly or quite twelve feet 

 in height. 



1 American Journal of Science, III. vol. xiv. p. 513, December, 1877. 



2 Jbid. vol. xviii. p. 504, December, 1879. See, also, vol. xix. p. 253, March, 

 1880 ; vol. sxi. p. 167, February, 1881 ; and vol. xsxiv. p. 413, November, 1887. 



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