the differences in the fauna of north and south america had been known for some time. both humboldt and darwin discussed it. the interchange as a concept was first fully laid out in 1876 by the "father of biogeography", alfred russel wallace. wallace had spent 1848–1852 exploring and collecting specimens in the amazon basin. others who made significant contributions to understanding the event in the century that followed include florentino ameghino and george gaylord simpson.