032 



REPORT OF NATIONAL MUSEUM, 1904. 



number of phalanges in the trucks of some of the animals classed 

 as Lithichnozoa, he confessed to a doubt if the animals heretofore 

 grouped under this name should be classed as birds; and. as a general 

 conclusion, announced that in fossil footmarks birds could not be dis- 

 tinguished from quadrupeds by the number of phalanges. In this 

 same paper he announced the finding of tracks which were accom- 

 panied by certain markings which were evidently made by the tail of 

 the animal, such being particularly characteristic of his Anisopus 

 gracilis, an animal the quadrupedal nature of which had already been 

 recognized. The presence of such tail-like markings in the case of 

 the Anomcepus lead him into a somewhat lengthy discussion as to the 

 affinities of this animal, whether bird or reptile, though he was evi- 

 dently inclined to regard it as most nearly related to a lower order of 



birds like the Archse- 

 opteryx. In support of 

 this, he appended a let- 

 ter from Professor 

 Dana, in which he re- 

 ferred to the general- 

 ized characters of the 

 early birds. 



Here the matter 

 would appear to have 

 rested until Mr. Ros- 

 well Field, a farmer of 

 Greenfield, Massachu- 

 setts, on whose prop- 

 ert} r the first slabs were 

 found, for the first 

 time in print voiced 

 his own opinions. In 

 the American Journal of Science, XXIX, 1860, he gave briefly and 

 modestly the results of his experience in collecting and observing, 

 and announced it as his opinion that the vertebral tracks should all be 

 classed as reptilian. That the animals that made them usually walked 

 on two feet he admitted, but contended that they could as well have 

 walked on four had they chosen. In proof of this he added: 



We find tracks as perfect as if made in plaster or wax winch, to all appearances, 

 as to the number of toes and the phalangeal or lateral expansions in the toes, agree 

 perfectly well with those of living birds, and still we know, by the impressions made 

 by their forward feet, that these fossil tracks were made by quadrupeds. 



In still other cases he noted traces of the tails tracking in the mud. 

 Enumerating some of the cases in which the so-called bird tracks — as, 

 for instance, the Otosoum, had been proven to be reptilian- he added 

 that this he verily believed is the place for them all. And in this he 



Fig. 123.— Skeleton of Anchisaurus colwus Marsh. 



