GROUND SLOTHS of immense size were among those mammals of a remote 

 age whose skeletal remains have been recovered from the tarry springs of 

 Rancho La Brea. Among prehistoric quadrupeds they ranked next to the ele- 

 phants in bulkiness but were dim-witted creatures and ill fitted to survive either 

 climatic changes or the fierce competition for existence in an era dominated 

 by carnivores. The sloths were herbivorous animals (Mylodon harlani) averag- 

 ing nine feet in length; many times larger than their arboreal cousins found in 

 the tropics today. 



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