380 AX IXTRODUCTIOX TO THE STUDY OF FOSSILS 



Fig. 163. — Outline restorations of some of the more characteristic mammals h'\Tng 

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

 uniform scale, w-ith a pointer dog (in the frame) to show relati^•e sizes, i. A 

 primitive rhinoceros (Hyrachyiis eximius) . 2-4 are creodonts, — primitive camivora. 

 2. Tritemnodon agilis, a form with hyena-like teeth. 3. Patriofelis ferox. 4. 

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

 cavity. 5. A primitive rodent (Paramys delicatior). 6. The huge ungxdate, 

 V intatkerium dticeps. This had an extremely small brain. 7. One of the smaller 

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



