XXIII 



COOPERATION OF MUSEUMS 



To the museums of the United States, Great 

 Britain, and Bavaria, where titanothere remains are 

 preserved, the author is indebted for cordial coopera- 

 tion in furnishing materials for study and in affording 

 every possible facility for measurements and illustra- 

 tions. The author would mention especially Prof. 

 Charles Schuchert and Prof. Richard S. Lull, of the Yale 

 University Museum, present custodians of the great 

 Marsh collections, as well as their assistant, Mr. 

 Thomas A. Bostwick, who is in charge of all the field 

 records of Marsh. In connection with the superb 

 Hatcher collection in the United States National 

 Museum, which far surpasses any other in existence. 

 Dr. Charles W. Gilmore and Dr. James W. Gidley 

 have rendered every possible assistance. The author 

 is especially indebted to the director of the Carnegie 

 Museum at Pittsburgh, Dr. W. J. Holland, and to 

 Mr. O. A. Peterson of that museum for the liberal 

 use of collections of the Uinta titanotheres; also to 

 Mr. Earl Douglass of the same institution for his 

 invaluable field notes and observations on the Uinta 

 section. The systematic location of species in the 

 great Uinta section is due to the precise field work of 

 Mr. Elmer S. Riggs of the Field Museum of Natural 

 History, Chicago, an institution that is especially 

 rich in remains from the horizon known as Uinta B. 

 To his former colleague Prof. William B. Scott of 

 Princeton University, as well as to his colleague 

 Prof. William J. Sinclair, the author is indebted for 

 the liberal use of valuable collections, including many 

 types from several levels of the Bridger and from the 

 uppermost Eocene horizon, known as Uinta C. 



From 1846, when the earliest remains of titanotheres 

 were found, until 1918 almost every year has added 

 one or more stages or types to the history of this 

 great family. The stages still to be discovered are 

 in the unknown interval between the uppermost 

 Eocene horizon, known as Uinta C, and the lowermost 

 Oligocene horizon, known as Chadron A. 



WORK ON TEXT AND ILLUSTRATIONS 



The great task of preparing the bulk of the manu- 

 script — a task performed between 1902 and 1918 — 

 fell upon Miss H. Ernestine Ripley, the work being 

 done chiefly from the dictation and notes of thp 

 author. The preparation of the bibliography and 

 the first revision of the entire manuscript were also 

 undertaken by Miss Ripley with interest and per- 

 formed with precision. The author warmly appreci- 

 ates this invaluable service to paleontology. The 

 final arrangement of the illustrations together with 

 the preparation of the accompanying legends, was 

 undertaken, under the author's general direction, by 

 Doctor Gregory with the cooperation of Miss Chris- 

 tine D. Matthew, Mr. Erwin S. Christman, and Mrs. 

 Lindsey Morris Sterling. The preliminary editorial 



work has been performed with celerity and skill by 

 Miss Mabel Rice Percy, of the American Museum. 

 The final arrangement and verification of illustra- 

 tions and captions were the work of Miss Christine 

 D. Matthew. 



The final editorial work and preparation of the text 

 for the printers were accomplished by Messrs. George 

 M. Wood and Bernard H. Lane, Mr. Wood continuing 

 the work as a member of the American Museum staff 

 after his retirement from the Geological Survey. 



The illustrations, which are taken from many 

 sources, date back to the early lithographic figures of 

 Leidy. They include the unpublished lithographic 

 plates prepared under the direction of Cope, and 

 especially the superb lithographic drawings made 

 for the United States Geological Survey by Mr. F. 

 Berger under Marsh's direction. These lithographic 

 plates are supplemented by numerous plates based 

 upon photographs taken chiefly by Mr. A. E. Ander- 

 son of the American Museum staff. 



The text and plates are adorned with reproductions 

 of the fine series of drawings from the pen and brush 

 of Mr. Christman and from the numerous pen draw- 

 ings of Mrs. Sterling. The geologic sections in 

 Chapter II are the work of Mr. William E. Belanske. 

 To Mrs. Sterling, Mr. Christman, and Mr. C. A. Weck- 

 erly of the Geological Survey were assigned the final 

 preparation for the photoengraver of all the illustra- 

 tions for the monograph, which, including those in the 

 Appendix, consist of 797 figures and 236 plates. 



This review affords a partial explanation of the 

 great length of the period of time occupied by the 

 author in the preparation of this monograph. The 

 work has involved repeated explorations in the West 

 in search of the remains of all the ancestors of the 

 family and in establishing the full chronology. It has 

 necessitated repeated journeys to all the museums of 

 the country and long and painstaking research. The 

 greatest effort, however, has been expended on the 

 solution of the series of related problems in stratig- 

 raphy, in adaptation, in the origin of new characters, 

 in the mechanics of locomotion, in the modes of 

 evolution, and in the causes of evolution and of 

 extinction that presented themselves as essential to 

 the exposition of the life history of a long extinct 

 family. To restore the living and the lifeless environ- 

 ment of the Rocky Mountain region and to present 

 the titanotheres as living forms has been the persistent 

 purpose of this monograph. 



SUMMARY OF GEOLOGIC AND ANATOMIC 

 PRINCIPLES 



The following is a brief statement of the principles 

 developed and discriminated in this monograph : 



1. The principle of the division and correlation of geologic 

 formations in Eocene and lower Oligocene time by mamma- 

 lian life zones and bv the subdivision of these zones. 



