LATER PLIOCENE EPOCH 



185 



of the horses were taller than the pony-sized creatures of 

 earlier times. Ground-sloths of South America had now 

 crossed the Isthmus (Megalonyx), adding a new feature to 

 the fauna. 



Many animals had quitted the northern for the southern south 

 continent, availing themselves of the recently raised land America 

 connection. Horses, mastodons, tapirs, lamas, and other 

 herbivorous emigrants were now well south of the isthmus ; 

 and carnivores, dog-like and cat-like, were not losing sight 

 of their commissariat. Marsupial life was augmented by 

 the arrival of some good-sized opossums. 



This invasion cannot have been without effect on the 

 southern fauna. But the continent was of vast extent, and, 

 so far as can be gathered, the development of the native 

 animals was not as a rule seriously checked. In some regions, 

 indeed, it progressed remarkably. Ground-sloths of larger 

 size than the Miocene forms were now in the forests (Mega- edentates 

 therium, Mylodon) ; and other Edentates were abroad, 

 resembling ant-eaters at least as regards the skull (Scelido- 

 therium). Armadillo-life was not only characterised by much 

 larger animals, but by a great variety of forms rigidly en- 

 cased. Some of the new kinds were shielded more elaborately 

 than their forerunners, and their tails were protected by 

 bony tubes and rings (JDcBdicurus, Panocthus). Ground-sloths 

 and armadillos were, therefore, rising to the occasion ; and, 

 as their later history will show, they had by no means ex- 

 hausted their adaptabilities. 



The various strange types of hoofed animals, such as 

 lived in South America in the Miocene, had by this time 

 undergone many changes and some losses. The astrapotheres, astra- 

 remarkable for doubly-tusked brutes of rhinoceros size, had potheres 

 become extinct. As some animals more or less allied, but 

 less formidably armed, were still in existence, the " lightning- 

 beasts " can hardly have perished from lack of brute force. 

 Brute force, however, had long been a declining power in 

 creation ; and it was probably owing in the main to mental 

 deficiencies that the astrapotheres failed to survive. 



Among their relatives, known as toxodonts, and suggestive toxodonts 

 in appearance of coneys overgrown, new species had arisen. 



