FOSSIL FOOTPRINTS FROM THE GRAND CANYON: 

 THIRD CONTRIBUTION 



By CHARLES W. GIL^IORE 

 curator of vertebrate paleontology, united states national museum 



(With Five Plates) 

 INTRODUCTION 



A third visit to the Grand Canyon in the late spring of 1927 enabled 

 me to collect additional fossil footprints, some of which are unde- 

 scribed species. Since there is no immediate prospect of acquiring fur- 

 ther specimens, it seems important that these, together with a speci- 

 men presented to the Museum by Mr. G. E. Sturdevant. naturalist 

 of Grand Canyon National Park, should be described, in order to 

 perfect as far as possible the record of the ichnites of this region. 

 While the above mentioned specimens from the Hermit and Supai 

 formations form the basis of the present paper, attention is also given 

 to a fourth ichnite fauna recently found in the Tapeats sandstone 

 of the Bright Angel section. These materials are fragmentary and 

 do not warrant systematic description. All are trails of invertebrate 

 animals, probably trilobites, a conclusion reached by the late Dr. 

 Charles D. Walcott from his study of similar trails from this same 

 formation in other parts of the Grand Canyon. 



I wish here to express to Dr. John C. iNIerriam and his associates 

 of the Grand Canyon Exhibit Committee of the National Academy of 

 Sciences my appreciation for the financial assistance which made this 

 third trip possible. I also wish to acknowledge again the help given 

 by various members of the Park organization. Superintendent M. R. 

 Tillotson furnished equipment and assistance of personnel ; Mr. James 

 Brooks, chief ranger, detailed ranger assistants; and Mr. G. E. 

 Sturdevant, Park naturalist, as on previous visits, contributed freely 

 of his time and energy to the successful outcome of the work in hand. 



NEW OBSERVATIONS ON THE GEOGRAPHICAL DISTRIBUTION 

 OF TRACKS IN THE GRAND CANYON 



The geographical range of fossil tracks in the Grand Canyon was 

 considerably extended through the opportunity offered of exploring 

 new localities. It would seem tiiat on tlie south rim of the Grand 



Smithsonian Miscell/sneous, Collections, Vol. 80, No. 8 



