﻿NO. 20 RECOGNITION OF PLEISTOCENE FAUNAS HAY 1 5 



and the apparent fact that all belong to Equus complicatus, we may 

 conclude that the numerous species which have been described be- 

 longed mostly to the older Pleistocene stages. 



Camels are well represented in the collections made in Nebraska 

 and Oregon, and are represented in the Aftonian. We might ex- 

 pect that the group would be represented in the Port Kennedy cave 

 collection, but its presence there is doubtful, and no remains are 

 known to occur in the Pleistocene of Florida. It is possible that the 

 camels had already died out in the eastern part of our country. 



On the other hand, no bisons are represented in the collections 

 made at Hay Springs, Nebraska, Christmas Lake, Oregon, and in 

 the Oregon Desert, as shown by Matthew's lists (Bull. Amer. Mus. 

 Nat. Hist., Vol. 14, p. 317). The group appears, however, to be 

 represented in the Port Kennedy collection by a few bones, and a 

 bison occurs possibly in the Aftonian. It looks, therefore, as if the 

 earliest Pleistocene was characterized by the existence of numerous 

 edentates, horses, camels, tapirs, and saber-tooth cats, and few 

 bisons, while during the later pre-Wisconsin Pleistocene there were 

 few edentates; few horses, no camels, few saber-tooth cats, but num- 

 erous bisons. 



The writer is inclined to the opinion that the mammalian fauna, 

 discovered in the Aftonian beds of western Iowa, is the equivalent 

 of that found in the Nebraska and Oregon localities referred to 

 above, as well as that of Port Kennedy cave, in Pennsylvania, and, 

 inasmuch as the level of the Aftonian beds is fixed in its relations 

 to the glacial drift-sheets, it seems proper to call the earliest known 

 assemblage of Pleistocene animals the Aftonian fauna. The suc- 

 ceeding fauna, if it shall prove worthy of recognition, may be known 

 as the Sangamon. Some fortunate discoveries in the interglacial 

 deposits known as the Yarmouth, the Sangamon, and the Peorian, 

 may enable future students to characterize accurately this Sanga- 

 mon fauna. It is the opinion of the writer that the contents of the 

 Conard fissure represent this fauna, but here few of the large mam- 

 mals have been preserved. 



The mammals that are included in the Aftonian and the Sanga- 

 mon faunas are practically those divided by Professor Osborn into 

 his Equus-Mylodon and Megalonyx faunas. This division appears 

 to be based on the presence of abundant moisture or the lack of it, 

 producing respectively forested and grass-covered regions. The 

 existing animals of North America have been divided by some 

 writers, into those of the forested region and those of the dry plains ; 



