216 THE AGE OF MAMMALS 



(Cervidse) rather than to the Old World chevrotains (Tragulus) or New 

 World camels (Camelidae) as had formerly been supposed. Thus in America, 

 as in Europe, there appear in the Lower Oligocene for the first time mammals 

 with a kinship to the cervine or deer division of the ruminants. 



In the Pipestone Creek beds of Montana our faunal knowledge has 

 been especially enriched by the discovery and description of the hitherto 

 unknown microfauna of the Titanotherium beds,^ which includes archaic, 

 tenrec-like forms, as well as erinaceids among Insectivora. These beds 

 belong near the base of the Oligocene (Matthew, p. 201). They contain 

 very primitive insectivores (Apternodus) with teeth of ancient type; also 

 a diminutive opossum (Peratherium titanelix). All the rodents belong 

 to the ischyromyid and hare divisions. None of the mice or squirrel 

 groups are found here. 



Cypress Hills, Saskatchewan. — In 1883 McConnell of the Canadian 

 Survey discovered Tertiary beds in the Cypress Hills, the northernmost 

 mammal-bearing horizons of Tertiary times. As described by Cope^ 

 (1891) and more fully by Lambe ^ (1908), the fauna is of Lower Oligocene 

 age, corresponding chiefly to that of the Lower Titanotherium beds of 

 Montana, although the upper members may be synchronous with the Oreo- 

 don Zone. The formation is fluviatile, or fluvio-lacustrine, and is widely 

 scattered from the Cypress Hills to the Swift Current Creek region. Its 

 fluviatile origin is attested by the presence of abundant remains of fishes, 

 including the bowfins {Ajnia), garpikes (Lepidosteus) , siluroids {Rhineastes) . 

 There are also numerous aquatic (Anosteira, Trionyx) as well as terrestrial 

 {Stylemys, Testudo) chelonians, lizards, snakes, and crocodiles. The 

 mammalian fauna includes opossums (Didelphys) and several species of 

 hysenodonts, including one animal of gigantic size (Hemipsalodon grandis), 

 also the true canids and machserodonts (Dinictis) characteristic of the 

 Lower Oligocene. The mammalian fauna in general is similar to that of 

 the Titanotherium Zone of Nebraska, South Dakota, and Montana. All 

 the titanotheres and several of the equines as well as rhinoceroses belong 

 to very primitive species. Of somewhat doubtful inclusion within this 

 fauna is the supposed ancylopod {Chalicotherium hilobatum) which rests 

 upon very uncertain evidence. 



White River beds of Montana and North Dakota.'* — The tertiaries of 



^ Douglass, E., New Vertebrates from the Montana Tertiary. Ann. Carncg. Mas., 

 Vol. II, no. 2, 1903, pp. 145-200. 



1 Matthew, W. D., The Fauna of the Titanotherium Beds at Pipestone Springs, Mont. 

 Bull. Amer. Mus. Nat. Hist., Vol. XIX, 1903, pp. 197-226. 



^ Cope, E. D., On Vertebrata from the Tertiary and Cretaceous Rocks of the North West 

 Territory. Geol. Surv. Canada, Contrib. to Canad. PalcBont., Vol. Ill, Montreal, 1891, pp. 1-25. 



' Lambe, L. M., The Vertebrata of the Oligocene of the Cypress Hills, Saskatchewan. 

 Canada Dept. Mines, Contrib. to Canad. Palwont., Vol. Ill, Ottawa, 1908, pp. 1-65. 



* Douglass, E., A Geological Reconnaissance in North Dakota, Montana, and Idaho; with 

 Notes on Mesozoic and Cenozoic Geology. Ann. Carneg. Mus., Vol. V, nos. 2 and 3, 1909, 

 pp. 211-288. 



