Fig. 9. — Footprint exhibit in situ in the Supai formation on the west side 

 of O'Neill Butte, Grand Canyon National Park, Arizona. (Photograph bv 

 Matthes.) 



Fig. 10. — Fossil trackway on large slab of Supai sandstone, quarried out 

 in building the new Yaki trail along the east side of O'Neill Butte. (Photo- 

 graph by Matthes.) 



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