1 86 



EVOLUTION IN THE PAST 



These for the most part consisted of larger animals than their 

 Miocene forerunners ; and it is evident from their teeth that 

 they were converging more closely to creatures of the rodent 



TYPOTHERES type (Toxodontotherium). The still more rodent-like typo- 

 theres, with an aspect of guinea-pigs grown to giants, had 

 also increased in size. 



LITOPTERNS The lama-like litopterns do not seem to have improved in 

 stature ; but it is of interest to note that in the case of some 

 of the animals the breathing aperture in the skull was located 

 higher up than in the Miocene forms (Scalabrina). This 

 suggests that a proboscis was in process of evolution. The 

 nasal modification, as will be seen, was carried still further in 

 litopterns of the next Period. The small forms, which had 

 anticipated horses in developing one-toed feet, seem by this 

 time to have been on the verge of extinction (Proterotheriidce] ; 

 whilst the antiquated hippopotamus-bears had quite passed 

 away (Pyrotherium). 



Although there were losses, it must be admitted that 

 the native fauna, at least in some regions, continued to 

 prosper. In parts of the continent, however, the quaint 

 aborigines were experiencing different treatment. Alien car- 

 nivores were levying heavy tributes, and extensive areas of 

 fertile land were being appropriated by hordes of new herbi- 

 vores. In short, a state of affairs was in prospect analogous 

 to that experienced by the South American natives when the 

 Spaniards invaded their dominions. 



AUSTRALIA Whilst the native fauna of South America had, as a whole, 

 lagged behind the animal-development in most parts of 

 the world, a still more backward condition existed in Australia. 

 Indeed, no mammals of higher rank than marsupials in- 

 habited that territory. This was doubtless owing to its 

 having become enisled before the commencement of the 

 Eocene Period. It had thus been cut off from the great 

 originating countries ; and the mammal life already far 

 committed to marsupialism proceeded with limited ana- 

 tomical resources. 



MARSUPIALS These resources, though restricted in scope, came well into 

 play, as testified by the variety of the fauna. Generalised 

 creatures with affinities to wombats as well as to kangaroos 



