Chapter 2. Cenozoic South American Metatherians (Mammalia, Theria) as Indicators of Climate–Environmental Changes

A noticeable aspect of metatherian evolution in South America is the influence of climatic oscillations in their macroevolutionary patterns, involving major radiations during warming phases, and extinctions and functional turnovers during cooling phases. Two aspects explain why southern metatherians were more successful than their Northern Hemisphere counterparts: a well-established presence previous to the arrival of eutherians and warm climates on a continental scale. Living South American marsupials reach a maximum species richness at the edges of tropical biomes, in areas of contact between tropical and subtropical biomes, or between subtropical and temperate biomes. Three biomes concentrate 80.6% of the records of living marsupials in South America, with tropical and subtropical moist broadleaf forests including the majority of them. South American marsupials are expected to suffer great losses of suitable habitat due to climate change and land conversion. Land exploitation will continue in the immediate future, probably being more disruptive to South American biomes than the current trend in global warming. We suggest that conservation efforts focusing on stenotopic species, such as those of Caenolestidae and Microbiotheriidae, should be given high priority.