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During Triassic time, the Dinosaurs attained in America an 

 enormous development both in variety of forms and in size. 

 Although comparatively few of their bones have as yet 

 been discovered in the rocks of this country, they have left 

 unmistakable evidence of their presence in the foot-prints and 

 otlier impressions upon the shores of the waters which they 

 frequented. The Triassic sandstone of the Connecticut Valley 

 has long been famous for its fossil foot-prints, especially tlie 

 so-called " bird-tracks," which are generally supposed to have 

 been made by birds, the tracks of which many of them closely 

 resemble. A careful investigation, however, of nearly all the 

 specimens yet discovered, has convinced me that there is not a 

 particle of evidence that any of these fossil impressions were 

 made by birds. Most of these three-toed tracks were certainly 

 not made by birds ; but by quadrupeds, which usually walked 

 upon their hind feet alone, and only occasionally put to the 

 ground their smaller anterior extremities. I have myself 

 detected the impressions of these anterior limbs in connection 

 with the posterior foot-prints of nearly all of the supposed 

 " bird-tracks" described, and have little doubt that they will 

 eventually be found with all. These double impressions are 

 precisely the kind which Dinosaurian reptiles would make, 

 and as the only characteristic bones yet found in the same 

 rocks belong to animals of this group, it is but fair to attribute 

 all these foot-prints to Dinosaurs, even where no impressions 

 of fore-feet have been detected, until some evidence appears 

 that they were made by Birds. I have no doubt that 

 Birds existed at this time, although at present the proof is 

 wanting. 



The principal genera of Triassic Eeptiles known from osseous 

 remains in this country are, Am2')hisaurus {Megadactylus), 

 from the Connecticutf Valley, Bathygnathus^ from Prince Ed- 

 ward's Island, Belodon and Clepsysanrus. Other generic names 

 which have been applied to foot-prints and to fragmentary 

 remains, need not be here enumerated, A few remains of 

 Reptiles have been found in undoubted Jurassic rocks of 



