Robust fossil evidence for Proboscidean frugivory and its lasting impact on South American ecosystems

Most megaherbivores in the Americas went extinct around 10,000 years ago, presumably disrupting the long-distance seed dispersal of large, fleshy-fruited plant species1. The neotropical anachronism hypothesis of Janzen and Martin2 is often used to explain many key adaptations of these "megafaunal fruit" plants, yet it lacks robust paleoecological evidence. Here, we use a multiproxy approach that provides unequivocal evidence of widespread frugivory by the extinct South American proboscidean Notiomastodon platensis. Using a model that reveals the extinction effects of these megafaunal dispersers in modern ecosystems, we show how losing these interactions has increased the extinction risk of megafaunal fruit plants in regions across South America lacking smaller surrogate dispersers. We further discuss the extent of functional changes that current ecosystems may undergo with continuing anthropogenic pressures.