marsh.] DINOSAURIAN FOOTPRINTS. 151 



the neck and the tail vertebrae were unfortunately lost, but the skull 

 and nearly all the rest of the skeleton were saved. The parts missing 

 are fortunately preserved in a smaller specimen of an allied species 

 (Anchisauriis solus) found at the same locality, and these have been 

 used to complete the outline of the restoration. Portions of two other 

 specimens, nearly allied, and from the same horizon, were also avail- 

 able, and furnished some suggestions of value. 



The restoration, as shown on PI. IV, indicates that Anchisaurus 

 colurus was one of the most slender and delicate dinosaurs yet dis- 

 covered, being surpassed in this respect only by some of the smaller 

 bird-like forms of the Jurassic. The position chosen is one that must 

 have been habitually assumed by the animal during life, but the com- 

 paratively large fore limbs suggest the possibility of locomotion on all 

 four feet. The compressed terminal digits of the fore feet, however, 

 must have been covered by very sharp claws, which were used mainly 

 for prehension, and not for walking. 



The small head and bird-like neck are especially noticeable. The 

 ribs of the neck and trunk are very slender. The tail apparently 

 differed from that of any other dinosaur hitherto described, as it was 

 evidently quite slender and flexible. The short neural spines and the 

 diminutive chevrons, directed backward, indicate a tail not compressed, 

 but nearly round, and one usually carried free from the ground. 



DINOSAURIAN FOOTPRINTS. 



The present restoration will tend to clear up one point long in doubt. 

 The so-called "bird tracks" of the Connecticut River sandstone have 

 been a fruitful subject of discussion for half a century or more. That 

 some of these were not made by birds has already been demonstrated 

 by finding with them the impressions of fore feet. Although no bones 

 were fouud near them, others have beeu regarded as footprints of birds 

 because it was supposed that birds alone could make such series of 

 bipedal, three-toed tracks and leave no impression of a tail. 



It is now evident, however, that a dinosaurian reptile like Anchi- 

 saurus and its near allies must have made footprints very similar to, if 

 not identical with, the "bird tracks" of this horizon. On a firm but 

 moist beach only three-toed impressions would have been left by the 

 hind feet, and the tail could have been kept free from the ground. On 

 a soft, muddy shore the claw of the first digit of the hind foot would 

 have left its mark, and perhaps the tail also would have touched the 

 ground. Such additional impressions the writer has observed in vari- 

 ous series of typical '-bird tracks" in the Connecticut sandstone, and 

 all of them were probably made by dinosaurian reptiles. On PI. V and 

 also \>. 146, fig. 2, are shown several series of Triassic footprints, which 

 were probably all made by dinosaurs. No tracks of true birds are 

 known in this horizon. 



