PRIMEVAL MAN 235 



generalized in type that they display close 

 affinities with the true cats, and even on cer- 

 tain points with the primitive dog creatures of 

 the time. Age followed age — Oligocene, Mio- 

 cene, Pliocene. The continents rose and sank 

 and were connected and disconnected. Vast 

 lakes appeared and disappeared. Mountain 

 chains wore down and other mountain chains 

 were thrust upward. Periods of heat, during 

 which rich forests flourished north of the arctic 

 circle, were followed by periods of cold, when 

 the glacial ice-cap crept down half-way across 

 the present temperate zone. Slowly, slowly, 

 while the surface of the world thus changed, 

 and through innumerable reaches of time, the 

 sabretooth cats and true cats developed along 

 many different Hues in both the Old World 

 and the New. One form of sabretooth was in 

 Europe with the bestial near-human things 

 who were the immediate predecessors of the 

 first low but entirely human savages. It was 

 in the two Americas, however, that the sabre- 

 tooth line culminated, immediately before its 

 final extinction, in its largest and most formi- 

 dable' forms. This California sabretooth was 

 not taller than a big cougar or leopard, but 

 was probably as heavy as a fair-sized lion. Its 

 skeletal build is such that it cannot have been 



