Splendid Isolation Revisited: The Entente Cordiale Model

Previous pages were the necessary introduction to understand the topics that are included in present chapter. Here the main pillars of a new model for understanding the history of Cenozoic mammals from South America are exposed. South America should not be viewed as a landmass that served as a refuge for non-competitive taxa or archaic and obsolete relics incapable of competing with any newcomer. The fact that South America was joined to Africa, Australia, Antarctica, and India during most of the Cretaceous, and that it was still connected to Australia, Antarctica and probably Africa, up to the Paleogene, points in favor to a complex palaeobiogeographical scenario. The strong biotic similarities between their faunas and floras are the result of interchanges or a common shared biota by these former Gondwanan landmasses. On the contrary, faunistic similarities with North America are very few, if any. The history of South American mammals has been told as a rather simple story, representing the perfect natural experiment, but fossil record and paleogeography demonstrate that the evolutionary history of the biota is much more intricate than envisaged. Perissodactyls, afrotherians, caviomorph rodents, monkeys, and others were widespread on southern continents by early Tertiary times, suggesting that southern continents may have played an important role in the early evolution and radiation of extant mammal clades.