386 "Prof. 0. C. Marsh — Restoration of Stegosaurus. 



In this restoration, the animal is represented as walking, and the 

 position is adapted to that motion. The head and neck, the massive 

 fore limbs, and, in fact, the whole skeleton, indicate slow locomotion 

 on all four feet. The longer hind limbs and the powerful tail show, 

 however, that the animal could thus support itself, as on a tripod, 

 and this position must have been easily assumed in consequence of 

 the massive hind quarters. 



• In the restoration as here presented, the dermal armour is the 

 most striking feature, but the skeleton is almost as remarkable, and 

 its high specialization was evidently acquired gradually as the 

 armour itself was developed. Without the latter, many points in 

 the skeleton would be inexplicable, and there are still a number 

 that need explanation. 



The small, elongated skull was covered in front by a horny beak. 

 The teeth are confined to the maxillary and dentary bones, and are 

 not visible in the figure here given. They are quite small, with 

 compressed, fluted crowns, and indicate that the food of this animal 

 was soft, succulent vegetation. The vertebrae are solid, and the 

 articular faces of the centra are bi-concave or nearly flat. The ribs 

 of the trunk are massive, and placed high above the centra, the 

 tubercle alone being supported on the elevated diapophysis. The 

 neural spines, especially those of the sacrum and anterior caudals, 

 have their summits expanded to aid in supporting the massive 

 dermal armour above them. The limb bones are solid, and this is 

 true of every other part of the skeleton. The feet were short and 

 massive, and the terminal phalanges of the functional toes were 

 covered by strong hoofs. There were five well-developed digits 

 in the fore foot, and only three in the hind foot, the first toe being 

 rudimentary, and the fifth entirely wanting. 



In life, the animal was protected by a powerful dermal armour, 

 which served both for defence and ofiience. The throat was covered 

 by a thick skin in which were imbedded a large number of rounded 

 ossicles, as shown in the figure. The gular portion represented was 

 found beneath the skull, so that its position in life may be regarded 

 as definitely settled. The series of vertical plates which extended 

 above the neck, along the back, and over two-thirds of the tail, is 

 a most remarkable feature, which could not have been anticipated, 

 and would hardly have been credited had not the plates themselves 

 been found in position. The four pairs of massive spines charac- 

 teristic of the present species, which were situated above the lower 

 third of the tail, are apparently the only part of this peculiar 

 armour used for offence. In addition to the portions of armour 

 above mentioned, there was a pair of small plates just behind the 

 skull, which served to protect this part of the neck. There were 

 also, in the present species, four flat spines, which were probably 

 in place below the tail, but as their position is somewhat in doubt, 

 they are not represented in the present restoration. 



All these plates and spines, massive and powerful as they now are, 

 were in life protected by a thick, horny covering, which must have 

 greatly increased their size and weight. This covering is clearly 



