162 



THE AGE OF MAMMALS 



Hyrachyus. The tapirs have not as yet been discovered in the Lower 

 Bridger. The mammal of most exceptional interest is the armadillo 



Fig. 61. — Outline restorations to same scale (X^o) of contemporary Middle Eocene 

 mammals. By Charles R. Knight. A. Notharctus, a primate, arboreal. JS. Orohippus, a 

 primitive horse, cursorial. C. Hyrachyus, a primitive rhinoceros. D. Tillotherium, a tillo- 

 dont. E. Dromocyon, a creodont, cursorial. F. Palwosyops, a titanothere. G. Metachei- 

 romys, an armadUlo, ambulatory. H. Patriofelis, a creodont. 



Metacheiromys, similar in many respects to the smaller existing armadillos, 

 but apparently possessing a leathery instead of a bony shield, the jaws 

 lacking the columnar enamelless teeth of the existing Dasypus, but defended 



