170 0. 0. Marsh — Restoration of 'Anchisaurus. 



position chosen is one that must have been habitually assumed 

 by the animal during life, but the comparatively large fore 

 limbs suggest the possibility of motion 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 locomotion. 



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 back- 

 ward indicate a tail not compressed, but nearly round, and one 

 usually carried free from the ground. 



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 clearly demonstrated by finding with 

 them the impressions of fore feet, similar to those made by 

 reptiles. Although no osseous remains were found with them, 

 others have been 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 

 Anchisaurus 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, 

 mud.ly 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 various series of typical "bird tracks" in the 

 Connecticut sandstone, and all of them were probably made 

 by dinosaurian reptiles. No tracks of true birds are known 

 in this horizon. 



The genus Ammosaurus, represented by remains of larger 

 size from the same strata, was a typical carnivorous dinosaur, 

 and apparently a near ally of Anchisaurus. So far as at 

 present known, the footprints of the two reptiles would be 

 very similar, differing mainly in size. 



The only other reptile known from the Connecticut sand- 

 stone by any part of the skeleton is a large Belodon from a 

 lower horizon. This crocodilian may be called Belodon validus, 

 and will be described by the writer later. 



New Haven, Conn., Jan. 21, 1893. 



