Introduction

The biogeographical history of the Cenozoic of South America mainly rests on the evidence yielded by the study of fossil mammals. This is probably because the seminal scientific authorities that worked on this topic were renowned paleomammalogists, including George G. Simpson, who established the “Splendid Isolation” model for South America. In this model South America remained isolated from the other continents during all of the Cenozoic, and consequently, its mammals evolved independently from any other landmass and had nothing to do with the origin of other groups elsewhere. Mammalian clades occurying in South America originate in the North, and arrived the continent through successive immigratory waves and the southern continents were regarded as dead-ends for the evolution of mammals. In spite that more tha 50 years have been passed away, since the last Simpson’s contribution, his model is followed nowadays by most Cenozoic vertebrate paleontologists. Under the new evidence provided by the natural world in the last decades, including the concept of movile continents, the “Splendid Isolation” model is too simplistic and should be rethinked. The aim of present book is to propose an entirely new view for the evolution of Cenozoic mammals in South America, supporting the view that biogeographic history of its biota is far more complex than stated by traditional models.