506 MANUAL OF ZOOLOGY. 



birds are in the form of footprints impressed upon certain 

 sandstones in the valley of the Connecticut River in the 

 United States. These sandstones are almost certainly Trias- 

 sic ; and if the ornithic character of these footprints be ad- 

 mitted, then Birds date their existence from the commence- 

 ment of the Mesozoic period, and, for anything we know 

 to the contrary, may have existed during the Palaeozoic 

 epoch. 



The evidence as to the ornithic character of the footprints 

 in the American Trias is as follows : — 



Firstly, The tracks are, beyond all question, those oi a. biped 

 — that is to say, of an animal which walked upon two; legs. 

 No living animals walk habitually upon two legs except Man 

 and Birds, and therefore there is a j>rim& facie presumption 

 that the authors of these prints were birds. 



Secondly, The impressions are mostly tridactylous — that is 

 to say, formed by an animal with three toes o)i each foot, as is 

 the case in many Waders and most Cursorial birds. 



Thirdly, The impressions of the toes show the same numeri- 

 cal progression in the number of phalanges as exists in living 

 birds — that is to say, the innermost of the anterior toes has 

 three phalanges, the middle- one has four, and the outermost 

 toe has five phalanges. 



Taking this evidence collectively, it would have seemed, till 

 lately, tolerably certain that these impressions were formed by 

 Birds. We must not, however, lose sight of the possibility 

 that these impressions may have been formed by Reptiles 

 more bird-like in their characters than any of the living forms 

 with which we are acquainted. The recent researches of 

 Huxley, Cope, and others, go to show that the Dinosaurian 

 Reptiles possessed the power of walking temporarily or per- 

 manently on the hind-ldgs, and many curious affinities to the 

 true Birds have been pointed out. It is therefore by no means 

 impossible that these footprints of the Connecticut valley are 

 truly Reptilian.* 



The size and other characters of the above-mentioned im- 

 pressions vary much, and they have certainly been produced 

 by several different animals. In the largest hitherto discov- 

 ered, each footprint is twenty-two inches long, and twelve 

 inches wide, showing that the feet were four times as large as 

 those of the African Ostrich. The animal, therefore, which 



* The occurrence of many yiJ«/;'-i'oia:^ impressions on tliese same sandstones, 

 and the further discovery of the bones of Dinosaurian Reptiles in the same 

 beds, have rendered the Reptilian nature of these footprints almost certain; 

 but some may possibly have been formed by Birds. 



