Yellowtail was a medicine man and Sun Dance cheif. Thomas was the principal figure in the Crow-Shoshone Sun Dance Religion during the last half of the 20th century. He was one of the most admired American Indian spiritual leaders of the last century.
Fred W. Voget, Professor Emeritus of Anthropology, Southern Illinois University, Edwardsville, was the author of "The Shoshoni-Crow Sundance", also published by the University of Oklahoma Press. Mary K. Mee, Voget's widow, assisted him in assembling the information for this book.