NO. 9 GRAND CANYON FOSSIL FOOTPRINTS GILMORE 2'J 



nally a slab 9 feet in length, the trackway extending the full length 

 without the slightest deviation to the right or left. 



The forefoot impressions are usually dimly impressed or absent. 

 In many places on the type slab this is due to the hindfoot having 

 been placed directly on top of the fore, thus obliterating the im- 

 print. Often, however, only the posterior half is thus wiped out. 

 In the paratype the hindfoot is shown falling in advance of the 

 fore, evidently caused by a slower gait and slightly shorter stride. 

 Judging from the relative depth of the impressions of the fore- and 

 hind feet, the greater part of the weight of the animal was borne 

 by the latter. The ratio of foot length to length of stride is about 

 I to 8. 



The feet were broad and stumpy with digits largely buried in the 

 mass of the foot. A few of the impressions made by the pes show 

 five short, rounded toes (fig. 17). None of the forefoot impres- 

 sions of the type gives any idea of the number of digits, but in the 

 paratype a few are suggestive of the presence of at least three. 



On the type slab (see pi. 5, fig. i, reproduced from a photograph) 

 a few shallow, half obliterated footprints of the manus may be seen 

 immediately in advance of those of the pes ; in the paratype the im- 

 prints of the manus fall behind those of the pes. 



The creature making these tracks was evidently narrow-bodied, 

 with long legs, and walked with an upright, mammalian-like stride. 

 Such an arrangement of quadrupedal tracks could be accounted for 

 only in this way. The straightness of the trackway and regularity of 

 the stride at once distinguishes the trail of Palaeopiis regidaris from 

 all others found at the locality. 



Genus BARYPODUS, new genus 



Generic characters. — Quadrupedal, with three digits in both manus 

 and pes. Digits long, nearly parallel, well separated ; appear to be 

 joined by web. Sole subquadrate, longer than digits. Forefoot placed 

 well forward of hind, both turned strongly inward. 



BARYPODUS PALMATUS, new species 

 Plate II, fig. I 



Type. — Catalogue number 11,134, U. S. N. M. Consists of a 

 slab on which are single impressions of a fore- and hindfoot. 



Type locality.- — Hermit Trail, Hermit Basin, Grand Canyon Na- 

 tional Park, Arizona. 



Geological occurrence. — Coconino sandstone (150 feet above base), 

 Permian. 



