152 DINOSAURS OF NORTH AMERICA. 



DISTRIBUTION OF TRIASSIC DINOSAURS. 



It is a remarkable fact that the seven skeletons of Triassic dino- 

 saurs now known from the eastern part of this continent are all car- 

 nivorous forms and of moderate size. There is abundant evidence from 

 footprints that large herbivorous dinosaurs lived here at the same time, 

 but no bones nor teeth have yet been found. In the western part of 

 this country a few fragments of a large dinosaur have been discovered 

 in strata of supposed Triassic age, but with this possible exception 

 osseous remains of these forms appear to be wanting in this horizon. 



Fragmentary remains, also, of dinosaurs have been found in the Tri- 

 assic deposits of Pennsylvania and North Carolina, but they throw little 

 light on the animals they represent. Footprints, apparently made by 

 dinosaurs, occur in New Jersey in the same horizon as those of the Con- 

 necticut Valley. Impressions of similar form have been discovered also 

 in the Triassic sandstones of New Mexico. A few bones of a large (lino- 

 saurian were found by Prof. .1. S. Newberry, in strata apparently of 

 this age, in southeastern Utah. These remains were named by Pro- 

 fessor Cope, Dystrophceus vicemalce, in 1877, but their near affinities have 

 not been determined. A single vertebra, apparently belonging in this 

 group, had been previously found at Bathurst Island, Arctic America, 

 and described by Prof. Leith Adams, in 1875, under the generic name 

 Arctosaurus. 



The European Triassic dinosaurs, with which the American forms 

 may be compared, are mainly represented by the two genera Theco- 

 dontosaurus Riley and Stutchbury, from the upper Trias, or Rhaetic, 

 near Bristol, in England, and Plateosaurus (Zanclodon) von Meyer, 

 from nearly the same horizon in Germany. The writer has investigated 

 with care the type specimens and nearly all the other known remains 

 of these genera found at these localities. 



Remains of dinosaurs have been found in Triassic strata, also, in 

 India, in South Africa, and in Australia, but the specimens discovered 

 were mostly fragmentary, and apparently indicate no new types. 



PART II. 



JURASSIC DINOSAURS. 



During the Jurassic period the dinosaurs of North America attained 

 remarkable development, and, as a group, appear to have reached their 

 culmination. The Theropoda, or carnivorous forms, which were so abun- 

 dant, though of moderate size, in the Triassic, were represented in the 

 Jurassic by many and various forms ; some were very minute, but others 

 were of gigantic size and dominated all living creatures during this age. 

 The herbivorous dinosaurs, however, were the most remarkable of all, 

 some far surpassing iu bulk any known land animals; others, also of 

 huge dimensions and clad in coats of mail, assumed the most bizarre 



