F. S. Riggs — Dinosaur Footprints from Arizona. 423 



Art. XXXIX. — Dinosaur Footprints from Arizona \ byE. S. 



Kiggs. 



A slab of sandstone bearing dinosaur footprints, recently 

 received at the Field Columbian Museum, is of interest in 

 marking a new locality for these well-known fossils. The 

 tracks were found in the bluffs overlooking the Colorado River, 



Dinosaur tracks one-fourth natural size. 



near Lees' Ferry in Northern Arizona. Mr. F. Y. Kearn, the 

 collector, reports that there were six impressions in all, but he 

 succeeded in preserving only two. The matrix is a sharp, fine- 

 grained sandstone of a bluff color when freshly broken, but 

 weathering to a dark reddish brown. Data as to the geo- 

 logical horizon are wanting, but it may be assumed that the 

 specimen is of Triassic age. 



The impressions are evidently made by the hind feet of a 

 tridactyl animal similar in structure to those of Allosaurus 

 Marsh, but considerably smaller. The tracks preserved are but 

 a few inches apart and were apparently made in wet sand. 

 That of the right foot is barely its own length in advance of 

 the left and is separated by a similar distance laterally. It may 



