SOUTH DAKOTA SCHOOL OF MINES 123 



teeth, vertebrae, limbs, and feet, is fundamental and indi- 

 cates a common pentadactyl ancestry of perhaps middle 

 Eocene time. 



Fossils representing various species of the family are 

 widely distributed over the earth, more particularly in the 

 old world. The name Anthracotherium (Coal-beast) arises 

 from the fact that their remains were first discovered in coal 



Figure 61 — Skeleton of the Oligocene Anthracothere, Hyopotamus 

 (Ancodus) brachyrhynchus. Scott, 1895. 



deposits, — the brown-coal deposits of Savoy. A few nearly 

 complete skeletons of Bothriodon the commonest Oligocene 

 form have been obtained from the channel sandstones of the 

 Big badlands. 



OREODONTIDAE 



The Oreodontidae include the commonest fossil mam- 

 mals of the White River badlands. Representatives of the 

 family are found only in North America. They originated 

 in the Eocene, ranged through the Oligocene and Miocene 

 and became extinct in Lower Pliocene. They are dis- 

 tinguished by many primitive characters and according to 

 Cope they constitute one of the best marked types of Mam- 

 malia the world has seen. They occupy a position some- 

 what intermediate between the ruminants (cud-chewing 

 animals) and the suilline pachyderms (pig-like thick- 

 skinned animals). 



