380 AN INTRODUCTION TO THE STUDY OF FOSSILS 



Fig. 163. — Outline restorations of some of the more characteristic mammals living 

 in North America during Upper Eocene (Bridger) time. These are reduced to a 

 uniform scale, with a pointer dog (in the frame) to show relative sizes, i. A 

 primitive rhinoceros (Hyrachyus eximius) . 2-4 are creodonts, — primitive carnivora. 

 2. Tt itemnodon agilis, a form with hyena-like teeth. 3. Patriojdis Jerox. 4. 

 Dromocyon velox, a big-headed, wolf-like form, though with a very small brain 

 cavity. 5. A primitive rodent {Paramys delicatior). 6. The huge ungulate, 

 Uintatkerium alticeps. This had an extremely small brain. 7. One of the smaller 

 early titanotheres (titanic beasts), Mesatirhinus superior. (From Scott.) 



