148 POPULAR SCIENCE MONTHLY. 



from sinking too deeply in the soft mud. The hand very rarely im- 

 presses, and but one instance is known of a dragging tail. What this 

 uncouth brute looked like, one can not even imagine, for no skeletal 

 remains are known which it in the least resembles. 



One very numerous group of large bird-like tracks unaccompanied 

 by hand or tail impressions seems from the blunted claws to have been 

 those of plant feeders, but of this we can not be sure, for the condor of 

 the Andes is also blunt clawed, and suggests the possibility that the 

 makers of these tracks may also have been carrion feeding, which would 

 place them among the carnivores. Certain it is that they were dinosaurs, 

 and among the largest of the valley forms, though probably but half 

 the bulk of their successors in the later rocks. One huge footprint 

 from Northampton, Mass., measures twenty inches in length and holds 

 four quarts of water. 



Quadrupeds. 



There must have been quite a host of quadrupedal forms in the 

 Triassic days, mainly of small size, but while they were probably of 

 amphibian or reptilian origin nothing was really known of them until 

 very recently. Professor Marsh found, some years ago, the remains 

 of one animal, but unfortunately only the impression of the armor of 

 the back remained, and, as the limbs were lacking, nothing could be 

 learned of its probable footprints. A second specimen has just been 

 brought to light, found in the village of Longmeadow, Mass., sufficient 

 of which is preserved to show that the creature was long of limb and 

 was probably a rapid runner. From its size and proportions, it corre- 

 sponds very closely with one of the most numerous of the quadrupedal 

 tracks. The Longmeadow specimen belongs to a group of primitive 

 crocodile-like reptiles, to which Professor Huxley has given the name 

 of Parasuchia. The footprints are small, but with a long interval 

 between the successive tracks, with sharp claws, with four toes on the 

 foot and five on the much smaller hand. Thus far only may we in- 

 terpret the quadrupedal footprints with any assurance, for beyond this 

 we are in the realm of almost pure conjecture, which in footprint in- 

 terpretation has thus far nearly always proved wrong. 



To summarize briefly, the footprint fauna contains amphibians, 

 * reptiles, and possibly birds ; of the first we as yet know nothing, but we 

 may be reasonably sure that they occurred; of the reptiles we have 

 identified numerous dinosaurs, representatives of both great land- 

 inhabiting orders, and we have also found indications of early crocodile - 

 like forms. Other reptilian orders were doubtless present, but what 

 they were we have as yet no means of knowing. Finally the only crea- 

 - hires which could have been birds could as readily have been dinosaurs 

 and such in all probability they were. 



