BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 22, pp. 207-216, PLS. 18-24 JUNE 14, 1911 



AFTONIAN MAMMALIAN FAUNA II ^ 



BY SAMUEL CALVIN 



. {Presented before the Society December 29, 1910) 



CONTENTS 



Page 



Introduction 207 



Fossilization and mode of preservation 208 



Carnivores 209 



Ungulates 210 



Horses 210 



Deer 211 



Camels 211 



Proboscideans 212 



Elephas 212 



Mastodon 213 



Other proboscidean remains 214 



Rodents 215 



Edentates 215 



Description of plates 216 



Introduction 



Since the preparation of the paper on the "Aftonian mammalian 

 fauna/^ which was published in October, 1909,^ a large amount of new 

 information and new material has been received. Our knowledge of the 

 surprising volume and geographic distribution of the Aftonian gravels 

 has been greatly extended during the past two seasons by the field work 

 of Shimek, who has devoted much time to the study of the problem and 

 has noted and recorded the occurrence of true Aftonian deposits at short 

 intervals over a wide belt, reaching from Sioux Falls, South Dakota, to 

 Eockport, in northwestern Missouri. There are reasons for believing that 

 the area studied includes but a mere fraction of that in which fossil- 

 bearing Aftonian beds are distributed. Aftonian deposits are found on 

 both sides of the Big Sioux and Missouri rivers ; they are known in Mus- 

 catine County and a number of other localities on the Mississippi, and 

 there are intermediate points where they are well developed. 



1 Manuscript received by the Secretary of the Society January 30, 1911. 



2 Bull. Geological Society of America, vol. 20, Oct., 1909, pp. 341-356. 



(207) 



