CHAPTER XII 



LIFE OF THE TERTIARY PERIOD 



DIRECTLY we pass from the Cretaceous into the lowest of 

 the Tertiary deposits — the Eocene — we seem to be in a new 

 world of life. Not only have the whole of the gigantic 

 Dinosaurs and the accompanying swimming and flying 

 reptiles totally disappeared, but they are replaced in every 

 part of the world by Mammalia, which already exhibit 

 indications of being the ancestors of hoofed animals, of 

 Carnivora, and of Quadrumana. 



Order — Ungidata 



In the Lower Eocene strata of North America and 

 Europe, the sub -order Condylarthra is well represented. 

 These were primitive, five-toed, hoofed animals which, Dr. 

 A. Smith Woodward tells us, " might serve well for the 

 ancestors of all later Ungulata." One of these, Phenacodas 

 pi'imczvus, was found in the Lower Eocene of Wyoming, 

 U.S.A., and was about 4 feet long exclusive of the tail 

 (see Fig. 72). Considering that this is one of the very 

 earliest Tertiary mammals yet discovered, it is interesting to 

 note its comparatively large size, its graceful form, its almost 

 full series of teeth, and its large five-toed feet ; affording the 

 starting-point for diverging modification into several of the 

 chief types of the higher mammalia. So perfectly organised 

 an animal could only have been one of a long series of forms 

 bridging over the great gulf between it and the small rat- 

 like mammals of the Mesozoic period. 



Another sub-order is the Amblypoda, of which the 

 Coryphodon of Europe and North America is one of the 

 best known. This was about 6 feet long, and was first 



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