266 TEN YEARS^ PROGRESS IX VERTEBRATE PALEONTOLOGY 



6. A discussion of paleogeography based on the migrations of verte- 

 brate faunas with special reference to some of the ideas formulated by 

 Suess and his followers would be a most valuable contribution to geology. 

 It must, however, be free from ail suspicion of special pleading, should 

 be based on mammals, land reptiles, and flightless birds, and should take 

 full cognizance both of what is known and what may be legitimately in- 

 ferred regarding the paleogeography of the late Paleozoic, the Mesozoic, 

 and the Cenozoic from the facts and theories of geology. 



7. The mapping according to modern methods of a few of the more 

 important mammal-bearing localities should be undertaken in coopera- 

 tion with governmental surveys. With the exception of a few White 

 Eiver areas in Wyoming and Nebraska, no detailed mapping of the con- 

 tinental Tertiary has been attempted. Topographic maps do not exist 

 covering the Wind Eiver, Bighorn, Wasatch, John Day, and many other 

 areas studied in great detail paleontologically. No wonder geologists 

 are disposed to question our results, and yet the paleontologist is not to 

 blame. The lack of maps has confined the efforts of the vertebrate 

 paleontologist to the methods of reconnaissance geology. 



8. All horizons affording vertebrates should receive careful petrologic 

 study both, with respect to the nature and origin of the sediments and 

 the conditions controlling deposition. Eeference has already been made 

 to some of the unexpected results attained by the use of the microscope. 



9. Finally, the vertebrate paleontologist should remember that geolo- 

 gists are not interested in the purely biological aspects of paleontology. 

 The vertebral formula of Eohippus does not thrill them with delight. 

 Why should it ? As the sister science of geology, paleontolog}^ is not and 

 can never be purely biological, and to the extent that geologic methods, 

 objects, and results are kept in mind by the paleontologist, by just so 

 much will he interest the geologist. Vertebrate paleontologists should 

 strive to produce results which are geologically paleontological. 



