| Unfortunately, the defensive adaptations of the large xenarthrans would have offered little protection against humans armed with spears and other projectiles. |
| Due in large part to the success of the xenarthrans, one area of South American ecospace the Nearctic invaders were unable to dominate was the niches for megaherbivores. |
| Elephant-shrews, xenarthrans, hystricognathous rodents, cetaceans, some pinnipeds, and primates depart sharply from this trend, however. |
| Likewise, some modern therians like afrotheres and xenarthrans have secondarily developed lower body temperatures. |
| Against this backdrop, the ability of South America's xenarthrans to compete effectively against the northerners represents a special case. |
| They are by far the most diverse group of xenarthrans, with 20 species in 8 genera. |
