218 DINOSAURS OP NORTH AMERICA. 



RESTORATION OF TRICERATOPS. 

 Plate LXXI. 



The abundant material now available, for examination makes it pos- 

 sible to attempt a restoration of one characteristic form of this group, 

 and the result is given in PL LXXI. This figure, about one fortieth 

 natural size, is reduced from a large outline plate of a memoir now in 

 preparation by the writer for the United States Geological Survey. 



This restoration is based mainly on two specimens. One of these is 

 the type of Triceratops prorsus Marsh, in which the skull, lower jaw, 

 and cervical vertebra: are in remarkable preservation. The other 

 specimen, although somewhat larger, is referred to the same species. 

 It consists of parts of the skull, of vertebra 1 , the pelvic arch, and 

 nearly all the important limb bones. The remaining portions are 

 taken mostly from other remains found in the same horizon and locali- 

 ties, and at present are not distinguishable specifically from the two 

 specimens above mentioned. The skull as here represented corresponds 

 in scale to the skeleton of the larger individual. 



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

 enormous head is in a position adapted to that motion. The massive 

 fore limbs, proportionally the largest in any known dinosaur, corre- 

 spond with the head, and indicate slow locomotion on all four feet. 



The skull is, of course, without its strong horny covering on the 

 beak, horn cores, and posterior crest, and hence appears much smaller 

 than in life. The neck seems short, but the first six cervical vertebras 

 are entirely concealed by the crest of the skull, which in its complete 

 armature would extend over one or two vertebrie more. The posterior 

 dorsals with their double-headed ribs continue back to the sacrum 

 itself, there being no true lumbais. although two vertebra;, apparently 

 once lumbais, are now sacrals, as their transverse processes meet the 

 ilia, and their centra are coossitied with the true sacrum. The four 

 original sacral vertebra' have their neural spines fused into a single 

 plate, while the posterior sacrals, once caudals, have separate spines 

 directed backward. 



Xo attempt is made in this restoration to represent the dermal armor 

 of the body, although in life the latter was more or less protected. 

 Various spines, bosses, and plates, indicating such dermal armature, 

 have been found with remains of this group, but the exact position of 

 these specimens can be, at present, only a matter of conjecture. 



This restoration gives a correct idea of the general proportions of the 

 entire skeleton in the genus Triceratops. The size, in life, would be 

 about 25 feet in length and 10 feet in height. 



DISTINCTIVE CHARACTERS OF GROUP. 



This group so far as at present investigated is very distinct from all 

 other known dinosaurs, and whether it should be regarded as a family, 



