South Dakota School of Mines 83 



motis power and the changes in the cranial portion allowing for 

 the attachment for the increasingly powerful muscles were in 

 strict correlation with the development of the saber-teeth. Along 

 with these changes was the degeneration and change in shape 

 of the lower jaw, allowing the mouth to be opened to an unusual 

 extent so as to give greatest freedom to the saber-teeth in stab- 

 bing the prey. The food of Hoplophoneus must have been in 

 large measure the thick skinned rhinoceroses, elotheres, oreo- 

 clonts, and other similar animals of the time. The lighter pro- 

 portioned Dinictis, with its less powerful canines, doubtless 

 preyed more successfully on the smaller swift-footed animals, 

 the securing of which demanded superior speed and endurance.* 



The Big Badlands furnished the earliest discovered remains 

 of Saber-tooth cats in America. Leidy, who described the first 

 species, gave it the name Machaerodus primaevus. Later this 

 was changed to Depranodon primaevus, and still later to Hoplo- 

 phoneus phimcievus, the name it now bears (see Plate 26). From 

 time to time other species have been discovered, until now eleven 

 are known. The reader will find a helpful review of the species 

 of cats from the badland formations of the Black Hills region, 

 as known some years ago, in a paper by Mr. George I. Adams 

 on the Extinct Fehdae of North America, published in the Amer- 

 ican Journal of Science, volume 1, 1896, pages 419-444. The 

 full list from the region as now recognized, is as follows : 



Lower Oligocene. 



Dinictis fortis, Adams. 

 Middle Oligocene. 



Dinictis felina, Leidy. 



Dinictis sqnalidens (Cope.) 



Dinictis pancidens, Riggs. 



Hoplophoneus primaevus (Leidy.) 



Hoplophoneus occidentalis (Leidy.) 



Hoplophoneus oreodontis Cope. 



Upper Oligocene. 



Dinictis bombifrons, Adams. 

 Hoplophoneus insolens, Adams. . . 

 Busmilus dakotensis, Hatcher. 



*For a fuller discussion of this, the reader is -referred to the 

 section on The Use of the Machaerodont Canine in W. D. Matthew's 

 paper, Fossil Mammals of the Tertiary of Northeastern Colorado, 

 Mem. Am. Mus. Nat. Hist., Vol. 1, 1903, pt. 7, pp. 385-387. 



