326 



HISTORICAL GEOLOGY 



Fig. 207 



Skeleton of an Eocene Creodont, Patriofelis. (After Osborn, from Cham- 



berlin and Salisbury's " Geology," courtesy of Henry Holt and Company.) 



Mesozoic Reptiles we found that certain forms took to the sea 

 and became truly marine Fish-like creatures, such as the Ichthyo- 



saur and the Mosasaur. So 

 in the Tertiary (even in the 

 Eocene) certain Mammals be- 

 came so adapted to the water 

 environment as to become 

 Fish-like forms, such as 

 Whales, Porpoises, etc., which 

 are often popularly regarded 

 as true Fishes. Apparently 

 we have here an example of 

 retrogression in evolution, be- 

 cause true land animals took 

 to the water and their legs 

 degenerated into swimming 

 paddles. Certain Whale-like 

 forms (Zeuglodons) of the 

 Eocene reached lengths up to 60 or 80 feet and must have been 

 extremely abundant, their vertebrae often being found in great 

 numbers in Alabama and other places. 



Fig. 208 

 One of the earliest Monkeys, Meso- 

 pithecus pentelici, from the Miocene 

 of Europe, restored by Gaudry. 

 Length of specimen, about 20 

 inches. 



